dipartimento di fisica - system and network administrationroberto/materiale/c.pdf · q:!pxb...

68

Upload: others

Post on 30-Sep-2020

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

���������� ����� �� ���������� ���� ������� � �! � ��#"$�! � �%�&

���������� ����� �# '$����()���! ��*+ ,�-�. /� 0

132547698;:=<?>A@CBD2

EGFIHKJ�LMEONQPSR�T�UVF7WXH7TZY[NQ\MF]UX^XE_N`U5ab aMaAcedgfMfihMhMh+NjH7TZY[NQ\MF]UX^XEON`UGa�fIk EiFIHKJlLME

mAn 2o>�pG8�q!rZ698 mAstsAm

Page 2: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ����������� �������������� ������������������

"!$#%!'&)(+*�,%-%.0/�*21�-%34!�,5!�,%-61�!

7 ^ b E�J98;: :Z6 :=<></8Z698$1@?5A�BCBED7 UVF a98 BD2=< 8�6 >FD7 Y�GMRME�a98 pXBD6IHA>%J :)q >7rtB4J 8�D7 HIRG\MPKGMLF8 pXBD6IHA>%J :)q >7rtB4J 8�4X>MLNLAB :OLZ698 : B @CB >7258�D7 P RIUGHQ8 258 @g@�RK2�pZ:6J > 6 8TSVUMRi:6JWRK2XUFR58Y<`B4LZ>5Z

[ !$.0/\*^]_!`(+*%! 8 J 8 4�BDq 8�2o@CB >�2ABa<`B4LAB :cb 8 8 J4d BD2=< 8�6 pZ:6J`J > 4�B pZ:6J > 6 B�L�8�6#B<`B4LAB2e >72o4 :Kq�8�2f< :6J B 4�B�4 :=<`B 258cJ : :o@g>�4IBQRK22d :Z6 :cb Bg< 8�<><hRX6 : :ji m rABg<�@g>72o>6 B :;@g@�RK2=< 8-258kJWJ :�@ 8_HMRo8�2=< 8l<g:Kr�8cJWJ :�Z

"!$#M( m�nM*2oQp^/�qrqT- !s* t%!`1 uv*21w/\xzy�-%3{3`( ,5!|y�-%3}(%x~!:cb :Z6 � 4 :��w� mAn :�� m �BD2f< i m 4 :�� m ��� n �6��i��V�2�

: m �_� n �2��i��k� n� >M:f< i m 4 :��~i%Z�� ��� sk��� :ji%Z�� ��� sk���4X>%RKr6J 8 �k� 4 :��w�NZ n ��� s ����� :��6Z n ��� s �����

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� §

Page 3: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� (Q,5!����V-61w(%x~! ,5!1 !s#%( 8 B q >�4�B�� : :=< > 6 B�4�B�<`B4L�> :cb 8 @CB :6L6L6J B : :K2o> :AB<`B4LABSBD2=< 8�6 B ^ b E�J 8 UVF a @g>72o>

7 T�U��AFSLtHQ8�: >72�@ 8_H�2o>KD7 \MF T�U��AFSLtHQ8 @ 8�2V:�@ 8_H�2o>KD7 GMRGF��98 q :XH�HIB >M6 8�@�</8�2;@CB >72o8�D7 T b R�JMa98 q�BD2o> 6 8 @�< 8�2o@CB >�258�D

[ !$.0/\*^]_!`(+*%!Y,%/^!l1�!$#%! !$*21�/\x>! - �Nn%! ] (+*^( ]�1�-61�!l-%#M#M3{!��V-61�! ! y�-2x~!.0(Q,5!����V-61w(%x~! 8

"!$#M( @!}1 uv*21w/\xzy�-%3{3`( ,5!|y�-%3}(%x~!RK2;@CB H72o8 4 :kb :Z6 � 4 : s : m����@CB H�258 4 :cb :Z6 � 4 :��w� mAn :�� m �@ b >M6I< �=� 4 :��~i mAn ���#:�i mtn � nRK2;@CB H72o8 4)@ b > 6I< �=� 4 : s :j� ��� i �@CB H�258 4 @ b >M6I< �=� 4 :��~i mAn ���#:�i mtn � nRK2;@CB H72o8 4 B 2=< i m 4 : s

: � m�� � � � ntm����@CB H�258 4 BD2=< i m 4 :�� m ��� n �6��i��V�2�

: m �_� n �2��i��k� nJ >�2XH � pG8 4�BSBD2=<��RK2;@CB H72o8 4 J >72XH � pG8 4�B+RK2o@CB H�258 4 BD2=<��@CB H�258 4 J >�2XH � pG8 4�B @CB H72o8 4 B 2=<��

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� �

Page 4: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� (%]�1�-%*21 ! 8 pZ:6J > 6 B � @g@CB :cb 8 2o>�2 L�>t@g@g>�2o> 8�@g@ 8�698 :6J </8�6 :=< B 4M:6JLZ6 >�H76 :Kq�q :��9L�>t@g@g>�2o>�8 @g@ 8�6 8

7 : :Z6 :=<></8�6 8 8 ej6 :�:NLAB : B @CBD2XHt>MJ B �,8 @fZ d :^d �hD7 B 2=</8Z698 8 2NRKq�8�6 B @ 8�2 :OLi:Z6I< 8lej6 : 5B >72G:Z6 B : �,8 @fZ � s�� � D7 B 2 pXBD6¤Ht>MJ : q >�rAB4J 8 8 26RKq 8�6 B : >�2 LG:Z6I</80e 6 : 5B >�2i:Z6 B : ��8�@fZ � m i%Zs� � �8XSG> B 2 2o>c<g: GB >7258$@ : B 8�2=<`B�� : : �,8 @fZ �6Z��6i�8h�~i ��Z

� 2i: : >t@�< :K2f</8 BD2=< 8�6 :��8!4K8kJ2<`B4L�> : >�q Li:=<`BDrAB J 8 LAB��R LAB :_: >MJ > :cb 8 J : L6R��>: >�2=< 8�258�698 : Li:Z6I<`BD698 4 : UVF a Z�� 2i: : >t@�< :K2f</8-B 2�pXBD6IHA>%J : q >�rAB4J 8�8 4X8cJ<`B4L�> : >�q Li:f< BDrtB4J 8 LtB��R LtB :�: >%J > :cb 8 J : L6R��> : >�2=< 8�258�698 : Li:Z6I<`BD698 4 :HIRG\MPKGML Z�78�6 :6J </8�6 :Z698 UFR58 @�<g: 6 8_HA>%J :!@CB+Ro@ :K2o> :6J : RK2AB @�R ��@g@CB

7 B 2=</8Z698 8�� � RK2o@CBgH7258 4���� � J >72=H � � � � RK2o@CB H�258 4 J >�2XHKD7 B 2!pXBD6¤Ht>%J : q�>7rAB J 8 8�� � � >K:=< D

"!s#%( ,5!�,%-61w( �+] /�. #%!�,5! �V(%]�1�-%*21 !BD2=< �l� m � nJ >�2XH � m iV� � � n � �Asts�� �~i �� >K:=< � m i%Z�� ��� � 8 � ���4X>%RKr6J 8 � m i%Z�� � �V8 � �:cb :Z6 d :^d

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� �

Page 5: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� (%]�1�-%*21 !�!s*21w/\xz/ 8

7 4X8 : BDq :NJ B 8 258�@g@�RK20LZ698 � @g@g> ��8�@fZ � sAm �hD7 >c<>< :6J B 8 LZ698 �I@g@g>�� �,8 @fZ s �����hD7 8�@ :54K8 : B q :6J B 8 LZ698 � @g@g>���� �,8 @fZ s���� � � Z

� -2x~!`-%t%!s34! 8 J > : : GB >7258 �gB �e4�B?q�8�q�> 6 B : : : RAB pXB 8�2o8 :o@g@g> : B :f< > RK2 2o>�q�88 : : RAB L6R��> 8 @g@ 8�698 :o@g@ 8_H�2i:=< > RK2 p�:NJ > 698 ��� ������������ � Z �O8Z2XHA>�2o>4�B :kb B :Z6 :=< 8#258cJK@ 8_HMRo8�2=< 8#q�> 4A> 8

������� �!�#"%$'&'()�!�#"%$*+(-,.,/,

0�@fZ 8+UVF a U21 341 5 Z6 Ri:K254A> @CB e : 6 B e 8�6 BDq 8�2=< > :6J+2o>�q�8 4K8cJ`J : pZ:Z6 B :KrAB J 8 @CB_@�<g: e : : 8�254X>6 Bge 8�6 BDq�8Z2=< > :6JM@�R;> : >72f</8�2NR=< >KZ�0 B q L�>M6I< :X2=</8�4�B @�<`BD2XH%R58�6 8 e 6 :

7 798 ��: 8<;+=�;�>?8 � � 8 pXB 8Z258 @�Lt8 : B � : :f< > B4Jj< B L�> 4K8kJWJ : pZ:Z6 B :KrAB J 8 q :2;>72 @g>�2o> 2o8 : 8 @g@ :Z6 B :Kq�8�2=< 8 :o@g@ 8�H72i:f</8 J 8 J > : : GB >72AB 4�B q 8�q > 6 B :6 8cJ :=<`B pG8�D

7 7 ��@�� 8A>?8 � � 8 pXB 8�258 @�Lt8 : B � : :f< > B4J"<`B4LZ> 4K8kJWJ : pZ:Z6 B :XrAB4J 8 8 @g>72o>:;@g@ 8_H72G:=</8�J 8 J > : :GB >�2AB 4�B q 8�q > 6 B : 698cJ :=<`B pG8�D

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� B

Page 6: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u¤*%!Wqc!W-%34!WqTqr-2qc!W(+*^/ 8 :6J`J4d :=<>< > 4X8cJWJ :$4�B :cb B :Z6 : 5B >�258 L6R �> 8 @g@ 8�698�:o@g@ 8�H72i:f< >B4J : >�2=</8Z26R=< >�4�B+RK2i:�p�:Z6 B :KrAB4J 8

������� �!�#"%$'&�������� �� $'&'()�!�#"%$*������� �� $*+(-,.,/,

0�@fZ 8+UVF a U � � 1 3 � �!1 5 � 3 Z

� (Q,5!����V-61w(%x~! ,5! - � �V/N] ] ( 8 @ 8Z6 p5>72o> : : >72f<C6 >%JWJ :Z6 8 J 8 q�> 4M:6J Bg< �: 4�B: :�: 8 @g@g>�8�q >�4�B�� : : 4K8cJWJ 8 pZ:Z6 B :KrtB4J B��7@g>�2o>7 ^XRGF Tia98 J : pZ:Z6 B :KrtB4J 8 2o>�2 L6R��> 8 @g@ 8�6 8 q >�4�B�� : :=<g: 4FRX6 :K2=< 8

J d 8 @ 8 : R 5B >�258 �+B J?p�:NJ > 698 B 2AB 5B :6J 8 �8 :o@g@ 8_H�2i:=< > <C6 :Xq�Bg< 8 BD2AB 5B :6J B� :f�5B >�258�D

7 P R2GME�a U�GMLF8 J : pZ:Z6 B :KrAB4J 8 LNR��> 8�@g@ 8�698 q >�4�B � : :f< : B 2 q >�4�B2;>72 @�Lt8 : B � : :f< B 8 @�L6J B : Bg< :Xq�8�2=< 8 4 :NJ LZ6 >�H76 :Xq�q : ��8�@fZ pZ:Z6 B :KrtB4J 8:;@g@g> : B :=<g: :NJWJ : HX8 @�<`B >�258.4�B+RK2 B 2=</8Z6,6)R6L=<�� Z

� 8�2XHt>72o> @�L�8 : B�� : :=<`BIB 2le :o@ 8�4�BX4IB :cb B :Z6 : GB >7258�8 L�>t@g@g>�2o> 8 @g@ 8�698 Ro@ :=<`B: >�2=< 8�q L�>M6 :K258V:Kq�8�2=< 8 8

" �� ?������� � �� $������ � �����%�!�#"%$ &�� � ����� �� $ &��

0�@fZ 8�^XRGF Tia HIRG\MPKGML c]U � � N������ �"!^XRGF Tia P R2GME�a U�GML UVF a ^NGMR�^+5 Z

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� #

Page 7: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

�|*MnM.0/\x)-2qc!W(5*^/ 8 J B @�< :�4IB : >t@�< :K2f< B 8 � � � = � 4X>c<g:=</8�4�Bl2o>�q�8 � �8�4K8 �]2ABg<g:4 :6J`J :�LG:Z6 >MJ : :cb B :VpG8 LGFM\��

LGFM\�� � � " $�� �!�#"%$ & � � ����� �� $ & � ( �!�#"%$ * � � ����� �� $ * � (-,.,/,��

0�@fZ 8 LGFM\�� J �AP � J�R�TMTXR 1 P L�J HIL 1 PKGG\ � � � � Z

?I8 B4JApZ:6J > 6 8 2o>72 �8 @�L�8 : B�� : :=< > �QJ 8 : >t@�<g:K2=<`BApi8Z2XHA>�2o>=BD2AB 5B :6J B� :=< 8 : >%JpZ:6J >M698�4X8cJWJ : : >t@�< :K2f</8jLZ698 : 8 4K8�2=< 8�:6RKq�8Z2=< :f< >�4IB'� �l:6J`J : LZ6 B q :!pXB 8Z258:o@g@ 8_H�2i:=< > B4JApZ:6J >M698 s Z

� 2i:=pZ:Z6 B :KrAB J 8 4�B�<`B4LZ> 8Z26RKq�8�6 : GB >7258 L6R��> :o@g@�RKq�8Z698 RK2;> 4X8iB pZ:6J >M6 B@�Lt8 : B�� : :=<`B 2o8cJWJ :�J B @�<g: 8$@CB�4�B :cb B :Z6 :cSXBD2AB 5B :6J B� : : >�q�8 8

� LGFM\�� � � � " $ � � � ���'� ��� � ��� � � �'� � $ & � � �� � ��� $ &�� (-,.,.,

� ���]1 8 BD2 A LGFM\�� �8�>�rKr6J B HM:f< >M6 B >KZ0�@fZ 8 LGFM\�� J �AP � J�R�TMTXR 1 P L�J HIL 1 PKGG\ � � � � ^XR2GMR�J�L��KJ�R�TMTXR !

LGFM\�� J �AP ^XR2GMR�J�L��KJ�R�TMTXR !J �AP ^XR2GMR�J�L Z

���#M/N,%/�& 8 J : Li:Z6 >%J : :cb B :VpG8 a��AcSLtHILtY : >�2o@ 8�2=< 8 J : 4K8 �]2AB 5B >�258 4�B26Ro>ZpXB 2;>7q�B�4�B2< B LABI4�B�4 :=<`BI:�Li:Z6E< BD6 8�4M:�UFRo8cJWJ B 8 @CB @�< 8�2=<`B

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� �

Page 8: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

a��AcSLtHILtY �������%� � " $

0�@fZ 8 a��AcSLtHILtY Y�GMRME�a P U5J ��R2GME � RGP]U�GML78Z6M4IB :cb B :Z6 :Z698 RX2i:[pZ:Z6 B :KrAB4J 8�Ro@ :K2o4X>.B4Jo26Ro>ZpG>.2o>7q 8 4IBh<`B4L�> @CBrLZ6 > : 8 4X8: >�q�8 : >�2�B^< B LAB^e >7254M:Kq�8�2=<g:6J B

0�@fZ 8 P U5J ��R2GME � RGP]U�GML TXR ��� E � � � � N � � Z� #M/�x)-61w(%x~! 8 @g>�2o> @CBDq�rZ>MJ B :kb 8 4�B : >�2o> :6J : >�q LAB J :=< > 698 4�B 8 @ 8_H%RABD6 8>%Lt8�6 :GB >�2AB 4�B pZ:Z6 B > <`B4LZ> @�R : >t@�<g:K2=<`B 8TS5> pZ:Z6 B :KrtB4J B � ;+=�� �� ��� � 8 �hD3:@ 8 : >�254 :�4K8kJS2NRKq�8�6 >-4�B :Z6¤HA>�q�8�2f< B5L�>t@g@CB :Kq�>-4�B @�<`BD2XH%R58�6 8�>%Lt8�6 :=< >M6 B7 � � ;+=�8 8 RX2 @g>%J >):Z6¤Ht>�q�8�2=< >KD9L�>t@g@g>�2o>):VpG8�698jRK2G: e >M6,q :

� � = ��@� ; �,@ 8Zq LZ698�� 8� � $�� � � ��� $ � � ���#"%$'� � � D

� ������ ; �/BD2 :6J : RK2AB : :o@CB�� 8� � ���#"%$'� � � � ��$�� ��� �� $ D

7 �98 � ;+=�8 8 4FR58!:Z6¤HA>�q�8�2f< B� � ���#"%$'� � � & � ��$ � � � �� $ � ����� " $'� � � * D

7 � � = � ;+=�8 8 < 698!:Z6¤Ht>7q�8Z2=< B{D

1 @ 8 : >7254M:�4K8cJV< B L�> 4�BX>%Lt8Z6 : 5B >72o8 LZ>A@g@CB :Xq > 4�B @�<`BD2XH%R58�698 p�:Z6 B 8 : J :o@g@CB4�B >ML�8�6 :=< > 6 B�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� �

Page 9: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

7 ;+= 8 � � �+� 8 � 8 D7 = ��� ;�>#8 9� ; � 8 ���< � 8 � 8 D7 �98 � � � = � 8 ��D7 798 ; �'� � � ; � ��� � ^D7 :NJ�<C6 B�>%Lt8�6 :=< >M6 B$D

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� �

Page 10: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� #M/�x)-61w(%x~!�-2x~!}1_.0/�1 ! ��! 87 RX2i:Z6 B >�� 8 @ 8_H�2o>FD7 rtBD2i:Z6 B � � � f 8 @g>�<><C6 : GB >7258 � :54K4�B�GB >�258 � q >MJ < B4LNJ B : : 5B >�258 �4IB pXB @CB >�258 ej6 : ^ b E�J)1 UVF a)1 Y�GMRME�a)1 HIRG\MPKGML D

7 rtBD2i:Z6 B >�� 8 q >�4FR6J > e 6 : UVF a D7 RX2i:Z6 B���� ��� 8 4X8 : 698�q 8�2=< > � BD2 : 698�q�8Z2=< > 4�BlRK2^dsRK2AB < �:^D b :K2K2o>

e > 6,q :� � = ��@� ; 8 J4d >%Lt8�6 : GB >7258 pXB 8�258�8 @ 8_H%RABg<g: � =�8 � ; 4�B%R;@ :Z698�B JipZ:6J >M6984K8cJ`J4d >ML�8�6 :K2o4X>KD

� ������ ; 8 J4d >%Lt8Z6 : 5B >72o8 pKB 8�258 8 @ 8_H%RABg<g: 7 � :VpG8�6 Ro@ :f< > B4JpZ:6J >M698�4X8cJWJ4d >%Lt8�6 :K254X>KZ

0�@fZ 8$UVF a U � � � 1 3 � �"!� � U !U � 3"!��� U � 3 b :�pZ:6J > 698 �%DU ��� � 3 b :�pZ:6J > 698 � Z

� #M/�x)-61w(%x~!Mxz/\3}-2q�!`(+*^-%3{!2/ 3`(\o+! ��! 8 = ��� ;�>#8 9� ; � � @CBX6 Bge 8�6 B @ : 8 :6JWJ 8 LZ>A@g@CBDrtB4J B698cJ : GB >72AB 698 : B LZ6 > :cb 8 e 6 : H%J B�:Z6IHA>�q�8�2=<`B�4K8_H%J B�>%Lt8Z6 :=< > 6 B rABD2G:Z6 B

7 � � 8 RXH%Ri:6J 8�:^D7 � � 8 4�B pG8�6 @g>�4 :^D

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦��

Page 11: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

7 � � � 8 q :XH�H B > 698 �?q :=H�H B > 6 8.> R=HMRi:NJ 8.4�B$D7 � � � 8 q�BD2;> 698 �?q�BD2o>M698.> RXH%Ri:6J 8�4�B$D

:cb 8 698 @�<`Bg< RAB @ : >�2o> B4J�6 B @�R6J�<g:=< > � � = � 6 :NL6LZ698 @ 8�2f< :=< > 4 : RX2 BD2=< 8�6 >4�B pG8�6 @g> 4M: 8Z6 > � > � ; � � 6 :6L6LZ698 @ 8Z2=< :f< > 4 :NJWJ4d BD2=< 8�6 > �8�6 > � @ 8 H%J B>%Lt8�6 :X254�B 9� �> � 9� 9� 258cJ`J : 698cJ : GB >7258 @�Lt8 : B�� : :=< : 4 :6J`J4d >ML�8�6 :=< > 6 8NZ�� � 8 ��=@CB 6 Bge 8Z6 B @ : 8 :AB q >�4�B BD2 : RtB�UFRo8 @�</8 698kJ : 5B >72tB;LZ>A@g@g>�2o> 8 @g@ 8�6 8: >%JWJ 8_HK:=< 8 <C6 :0J >M6 > q�8 4IB :K2=< 8YH%J B >ML�8�6 :=< > 6 B7 rtBD2i:Z6 B >���� 8 1 �� J >�H B : >FD7 rtBD2i:Z6 B > � 8 ��� J >�HIB : >KD7 RX2i:Z6 B > � 8 � � � J >�H B : >KZ

:cb 8 : :�: 8�<~<g:K2o> :Z6¤HA>�q�8�2f< B : p�:NJ > 6 B � � = > � ; � �Z B 2 HA8�258�6 :NJ 8 RX2i:UFRi:NJWRK2TUFRo8�8 @�LZ6 8 @g@CB >�258 �8�� � =�; @ 8 �8 7 8 � � = ; 7�; > � = ���� ; � ; @ 8%� � � ; � �; > � = �Z0�@fZ 8$UVF a U � � � 1 3 � �41 5 � �"!

3 � � 5 b :!pZ:6J > 698�� � = � �8��'� = ; �hDU � � 3 �8�� ; � ; DU � � 3 �8�� � = ; D� U �8�� ; � ; DU ��� � �8�� ; � ; DU � 3 �8�� � = ; Z

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� §��

Page 12: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� #M/�x)-61w(%x~! t%!}1 #M/\x t%!}1 8 :XH B @ : >�2o> @�R :Z6IHA>�q�8�2=<`B 4�B�< B4LZ> BD2=< 8�6 > >: :Z6 :f<~< 8�698�pXB @�<`B : >�q�8$@ 8�UFRo8�2 �8�4�B rABg< �Q>%Lt8�6 : GB >72AB�4�B ri:o@g@g> J B pi8kJWJ > �7 rtBD2i:Z6 B >�� 8 1 ���D7 rtBD2i:Z6 B > 8 ��� D7 rtBD2i:Z6 B > � 8�� ��� > ��� 8 @ : JWRo@CB p5>FD7 RX2i:Z6 B > k 8 � � � > : >�q L6J 8�q 8�2=< >):�RX2o>KD7 rtBD2i:Z6 B�� � 8 @ b BgeC<3:�@CBD2AB @�< 6 :��I@ b BgeC<3: 4K8 @�< 6 :^D

0�@fZ 8$UVF a U � �!1 3 � � 1 5 � � !U � 3 b :!pZ:6J > 698 s DU 3 b :!pZ:6J > 698 i%D5 � � b :�p�:NJ > 698 �%Z

� #M/�x)-61w(%x~!Q,5!+-2] ] /�oQ*^-%.0/\*21w( 8 Lt8Z6,q�8�<>< >�2o> 4�BM:o@g@ 8_H�2i:Z698 RK2$pZ:6J >M698:ORK2i:�p�:Z6 B :KrAB4J 87 rtBD2i:Z6 B > � 8 :o@g@ 8_H�2i:Kq 8�2=< >#@ 8�q LNJ B : 8 �

�� � � ��'� � $ � ����� �� $ D

7 rtBD2i:Z6 B > � � � � � � f�� 8��� � � �'� � $ � ��$�� ��� �� $ � ����� �� $

�8�8�UFRAB pZ:6J 8�2=< 8�:��� � � �'� � $ � �� � � ��'� � $ � � $�� � � ��� $ �� � ��� $ D

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� §�§

Page 13: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� d :;@g@ 8_H72G:Kq�8�2=< > :6JWJ d >ML�8�6 :K254A> 4IB#@CBD2AB @�< 6 : �8 J4dsR6J�<`BDq : >ML�8�6 : 5B >�2588 @ 8_H%RABg<g:��9LZ6 BDq :�pXB 8�258 pZ:6JWR=<g:=< > J4d >%Lt8�6 :X254X>�4�B�4K8 @�< 6 :�Z0�@fZ 8$UVF a U � � � 1 3 � � !

U � 3 � U b :�pZ:6J > 6 8 m DU � � 3 � U b :�pZ:6J > 6 8 � m DU � � � � 3 � U b :�p�:NJ > 698 m D

� x~!`(%x~!}1��- / -2] ] ( ��!`-61�!`y^!}1��- 8 J4d : 5B >72o8 4K8_H%J B >ML�8�6 :=< > 6 B[BD2 8 @�LZ6 8 @g@CB >�2AB: >�q L6J 8�@g@ 8 �8#698_Ht>%J :=< >�4 :

7 � = 8 =�8 ���; � = ����� 7 ��� >�; 8 B 2 LZ698 @ 8Z2 V: 4�B+LAB��R >ML�8�6 :=< > 6 BM@�L�8 : B�� : :�BD2UMRi:6J 8 > 6 4�BD258 :XH B @ : >�2o> >%Lt8�6 :=< >M6 B;4�B pG8�6 @CB{DA>%Lt8Z6 :=< > 6 BV4�BNLZ6 B >M6 Bg< �:lLAB��R8kJ 8 pZ:=<g: b :K2K2;> J : LZ6 8 : 8 4K8Z2 V: @�R >ML�8�6 :=< > 6 B�4�B|LZ6 B >M6 Bg< �: LAB��R rG:o@g@ :� pG8 4K8Z698 < :Kr�8cJWJ : ��Z

7 ; � � 8<; � 8 � 8 ���; 8 BD2 LZ6 8 @ 8�2 : 4�B LAB��R >ML�8�6 :=< > 6 B @�Lt8 : B � : : BD2 UFRi:NJ 8>M694�BD2o8!:=HIB @ : >72o>�>%Lt8Z6 :=< > 6 B : >�20J : @�< 8 @g@ :OLZ6 B >M6 Bg< �:2D

B 2 8�2=< 6 :Kq�rAB B : :;@CB J 8 Li:Z698�2f</8 @CB ��� L�8�6,q�8�<>< >72o> 4IB :6J </8�6 :Z698UFR58�@�<�d >M694�BD258�D0�@fZ 8 � 8 �-@g>�2o> ; � � 8<; � 8 � 8�; 8 � 8 � =�; 8 b :K2X2o> J :�@�</8 @g@ :OLZ6 B >M6 Bg< �:��

E � P � ^ pXB 8Z258$pZ:6J`R=< :f< : : >�q�8 � E � P � � ^ D� � 8 � � @g>72;> ; � � 8<; � 8 � 8�; 7 � � = ; 8 b :K2K2;> J : @�< 8 @g@ :0LZ6 B >M6 Bg< �:��E � � P � � ^ pXB 8�2o8$pZ:6JWRf< :=<g: : >7q 8 E � � � P � � ^ �^D

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� § �

Page 14: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� b : RK2G: LZ6 B >M6 Bg< �: LAB��R 8cJ 8 pZ:=<g: 4�B � � E � P � ^ pXB 8�258�p�:NJWRi:=<g:: >7q�8 E � � P � ^ �^D

� xz/ �V/6,%/�*^qr- � #M/�x)-61�(%xz/�#:XH�H B > 698 ��� ��� � � dMd N

��� ��� � � k � � � � ^XE�Tia �T�U��ILMRtY FSLih HIL2GML�a�LN � � � �� f �� �� �

� � � � � �� � � ��

���

� d�)BD2;> 698 � � � � � � � f�� � �

� � � � � � � � �

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� § �

Page 15: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

�5]�#�xz/N] ]_!`(+*%! 8 UFRG:6J @CB :o@CB : >�q�rABD2i:GB >�258 pZ:6J B 4 : 4�B!�' � ; � � 8 � � ;+=�8 ; � 8 � 8 8 � � = ; �� =�8 D b : RX23pZ:6J >M698 :;@g@g> : B :=< > :cb 8 �8 4 :f< >.4 :tB;pZ:6J >M6 BG4�B : >t@�< :K2f< Bo8pZ:Z6 B :KrtB4J B��X834K8GBM6 B @�RNJ�< :f< B54K8cJWJ4d :GB >�258 4X8_HMJ B5>%Lt8�6 :f< >M6 Bo@�R"UFR58 @�< 8lRNJ�< B q�8NZB 2 q >%J�< B�4K8iB : :;@CBSB 2 : RtBI:XrKrAB :Kq�> Ro@ :=< > B4JN</8Z6,q�BD258 � ; � = � �9L�>t@g@CB :Kq >LAB��R�BD2 HX8�2o8�6 :6J 8$@g>t@�< B <hRAB 6)J > : >�2%� � = � � 8 9� �XZ0�@fZ 8$UVF a U21 341 5 !

� � U � 3 � 5 !� � � U � � 3 � ��� � 5 � � � ��Z

� (+*^y�/\x)]_!`(+*^/ ,5!"1�!$#M( 8 UFRi:K2o4X> RK2^d 8�@�LZ698 @g@CB >�258 : >�2=<`B 8�258 : >t@�<g:K2=<`B8!pZ:Z6 B :KrAB J B 4IBM<`B4LABMe >�254 :Kq 8�2=<g:6J Bl4�B pG8�6 @CB �9UFR58�@�</8!pG8�2XHt>72;> : >�2VpG8�6I<`Bg< 8BD2 RX2 RK2AB : > <`B4LZ>5Z � R=<><`B�HMJ B >%Lt8�6 :X254�B pG8�2XHt>�2o> : >72 pi8Z6I< B < B 258cJ'<`B4L�>4K8cJ`J4d >ML�8�6 :K2o4X> � q�:XH�H B >M698�� � >%Lt8Z6 : 5B >72o8 L�8�6�>ML�8�6 : 5B >�258NZ7 ^ b E�J � UVF a � UVF a D7 ^ b E�J�fIUVF a�ftY�GMRME�a � HIRG\MPKGML � HIRG\MPKGML Z

0�@fZ 8 4 :=< 8 J 8 pZ:Z6 B :KrAB J B ^ b E�J ^ b 1 UVF a U21 Y�GMRME�a Y 1 HIRG\MPKGML H �258cJ`J4d 8 @�LZ698 @g@CB >7258 � ^ b f U � � � Y � H ��� ^ b pKB 8�258 : >�2VpG8�6I<`Bg< > :UVF a 8 Y : HIRG\MPKGML 6 B @�Lt8�<><`B pZ:Kq�8�2=< 8 LZ6 BDq : 4K8cJWJ : 4�B pXB @CB >�258 8 4K8cJ`J :q >%J�<`B4L6J B : : GB >7258�D B4J 6 B @�R6J�<g:=< > UVF a 4�B � ^ b f U � pXB 8�258 : >�2VpG8�6I<`Bg< > :4X>%RKr6J 8 LZ6 BDq�: 4K8kJWJ :�@g>7q�q�:�Z

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� § B

Page 16: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� -2]�1 8 Lt8�6Qq�8�<></8 4IB�e > 6 :Z698 RK2^d 8�@�LZ698 @g@CB >�258 Lt8�6 :cb �8 @CB : 4�B RK2 <`B4L�>@�Lt8 : B�� : >5Z

� � � � � � $ � � � $ � � � �#�!$ D

1 � � 0 ��� B � � 0 8 B4J � ; ��BD2ABDrtB @ : 8 B4J : >72=< 6 >%JWJ > @�RtB <`B4LAB >%Lt8�6 :f< > 4M:6J: >�q LAB4J :=< >M698��0�@fZ 8$UVF a U21 3"!

Y�GMRME�a � � � � � N ��L � � !U � � � B4J : >7q LtB4J :=< > 698�:Vp;pG8�6I< 8 :cb 8 B 4MR58 <`B4LAB @g>�2o> 4�B pG8�6 @CB{D3 � � UVF a � � � 258�@g@�RK2�: popG8�6E< BDq 8�2=< >����

� 3 1_x~!k(+#M/\xz-61�(%x>! 8 J4d >ML�8�6 :=< > 6 8 � 8 =�� � ; @CBcR;@ : Lt8Z65J 8�HM:Z698�:o@g@CB 8�q 8 q >%J�< 88 @�LZ698�@g@CB >72tB 258kJ q >�4X>#@ 8_HMRo8�2=< 8

$ � � � $ � � � � �!$ & ( $ � � � $ � � � � �!$ * (-,.,/,

8 B4JXpZ:6J > 698#6 B @�R6J < :K2f</8 �8 UFR58cJWJ > 4K8cJWJ4d 8�@�LZ698 @g@CB >�258 LAB��R : 4K8�@�<C6 :^Z0�@fZ 8$UVF a U21 3"!

U � � 3 � � � 1 3 � � ��� B b :!pZ:6J >M698 ���NZ

� d >%Lt8Z6 :=< > 698 < 8�6,2i:Z6 B > � d�b :OJ :�@ 8_HMRo8�2=< 8.@CB 2=< :;@g@CB

$ � � � $ � � ���#�!$ & � $ � � � $ � � � � � $* d $ � � � $ � � ���#�!$ � Z

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� § #

Page 17: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

6 BDq :$pXB 8Z258 pZ:6JWRi:f< : $ � � � $ � � � � �!$ & ��@ 8 UMR58 @�<g: �8 � � = ; B J�6 B @�R6J < :=< > �8�B4JpZ:6J >M698�4IB $ � � � $ � � � � � $ * ��:6J�< 6 BDq 8�2=<`B5UFRo8cJWJ > 4�B $ � � � $ � � � �#�!$ � Z � >c< :Z6 8:cb 8 @ 8 $ � � � $ � � � � �!$'& �8 � � = ; $ � � � $ � � ���#�!$ � 2o>72 pKB 8�258 pZ:6J`R=< :f< :��[@ 8BD2VpG8 : 8 �8 e :6J @ : $ � � � $ � � � � �!$ * 2o>72�pXB 8�2o8$pZ:6JWRf< :=<g:�Z0�@fZ 8$UVF a U � �!1 3 � � 1 5 � � 1 G !

G � � U � � � � � � � 3 d 5 � � � G b :!pZ:6J >M698l�KDG � � U � � � � � � � 3 d 5 � � � G b :!pZ:6J >M698 � Z

� (+. .0/\*21 ! 8 J 8)4MR58 : >MLNLAB 8�4�B : :Z6 :f<~< 8�6 B�� f � d�8 � � f d�4K8kJ BDq�Bg<g:K2o> RK2: >�q�q�8�2f< >�8 < R=<>< >YUFR58kJWJ > :kb 8 @�<g:"e 6 :�UFR58 @�< 8 R6J�<`BDq�8 �j:X2 :cb 83@�R!6 B H b 84�B pG8�6 @ 8�� pXB 8Z258 B H�2o> 6 :f< > 4 :6J : >�q LAB4J :=< >M698NZ B 2 A���� � q�: 2o>72 B 2 A �pXB 8�258 : >72o@CB 4K8�6 :=< > : >7q!q�8�2=< > :X2 :cb 8 < R=<>< > : B �> :cb 8!@ 8_H%R58OJ : : >ML6LtB :4�B : :Z6 :=<>< 8�6 B�� fMf d �]2o>):6JWJ : �]258�4K8cJWJ :�@�< 8 @g@ : 6 B HK:�Z0�@fZ 8$UVF a U !

UVF a 3 � � ! f � UVF]U��SUtE2GIU�� �IE �SUtRGFSL � fU � � ! fMf E�TMTXL �AFSE � LGF a�R

�c�����������)�z�����{���`� �C¡9�C¢v�£���C¢$¢¤�¥��¦�� § �

Page 18: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ���������9�E����

u$]�1_x n^qc!W(5*%! 8 � rNJ > :�:cb B � e >7254M:Kq�8�2=<g:6J B�:=<><C6 :VpG8�6 @g> B�UFRi:6J B @CB @ pXB4JWRNL6Li:B4J � Ro@g@g> 4K8cJ LZ6 >�H�6 :Kq�q :2D RK2^d � � = � � 8 9� � pZ:6J B 4 : < 8�6,q�B 2i:=<g: 4M:6J: :Z6 :f<~< 8�698 � ! ���8 RK2^d 8 � = � >?8 9� �XZ

� x)(�o+x)-%. .0-2q�!`(+*^/ ]�1�x n21�1_nMx)-61w- 8 J d B 4K8;: 4IB ri:o@ 8-4K8kJWJ : � = � =�; � � ;��>#8 �9� � = ��� � � = ; � ; �8 :kb 8 B4J � Ro@g@g> 4IB�8 @ 8 : R 5B >72o8 4X8cJ�LZ6 >�H�6 :Kq�q�:4K8 pG8 6 B @�R6J < :Z698 8 pXB 4K8Z2=</8 4 :6J`J : @�< 6)R=<><hRX6 : @CB 2=< :f<~<`B : : 4K8cJ </8�@�< > 4X8cJLZ6 >�H76 :Kq�q :�Z

� 8 B @�< 6)R 5B >�2AB#BD2 : >72f<C6 :f</8 �]2o> 6 :�� 8 : B >��8 J 8 � � = � � 8 9� 8 � pi8Z2XHA>�2o>8 @ 8_H%RABg< 8 BD2�@ 8_UFR58�2 : 258cJ`J4d > 694IBD258$BD2 : RAB : >7q LG:AB >�2o>�2o8cJX</8�@�< >KZ ?I8�2 :L�>c< 8�6 :6J�< 8�6 :Z698YUFR58 @�< d > 6 4�BD258�:VpM698�q!q >�4 :Vp;pG8�6 > LZ> : : � 8 @g@CBDrtB4J Bg< �:�Z

u$]�1_x n^qc!W(5*%! ,5! �V(5*21_x)(53$3}( 8 : >72=< 6 >%JWJ :K2;> B4J � Ro@g@g> 4�B 8�@ 8 : R 5B >�2584K8cJ LZ6 >�H�6 :Kq�q�: 8 Lt8�6,q 8�<~< >�2o> 4�Be:NJ�</8Z6 :Z698 J4d >M694�BD258 4�B 8�@ 8 : R 5B >�258@�< 698�<>< :Kq 8�2=< 8 @ 8�UFRo8�2 5B :6J 8�4�B @ : Ro@g@g>�@g>%LZ6 :�Z �>t@g@CB :Kq�>!4�B @�< BD2=HMR58Z698 < 698: :=< 8_Ht> 6 B 8�4IB 8 � = � >#8 9� 8 798 ��9� � = � � ���8 : B >��8 B @�<C6zR GB >72AB 4�B7 '� � � >#8 �9� 8+UGYIfML2G�TXL � UGYIfML2G�TXL � T5h U5al^ b D7 8 ��� =�;�>?8 � � � 8 ��� 8 8OYIR�J � h b U�GML � HIR � h b U�GML D7 ; � �� 8 P J�LME#5 � ^XRGF a UVFM\SL � ��R�a�R Z

� ¢{�I�����¥��¦�� § �

Page 19: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*^/ UGYIfML2G�TXL � UGYIfML2G�TXLF8 J : @CBD2=<g:o@g@CB+LAB��R HX8Z258�6 :6J 8 �8UGY � $ � � � $ � � � � �!$ & �� �'� ������� � � $ &

� L2G�TXL UGY � $ � � � $ � � ���#�!$* ���� ���'� �����'� �#�!$ * �

� L2G�TXL UGY � $ � � � $ � � ���#�!$ � ���� ���'� �����'� �#�!$ � �,,� L2G�TXL �

� ���'� �����'� �#�!$ �� 8 8 @�LZ698 @g@CB >�2AB :cb 8 : >7q Li:AB >�2o> 4X>MLZ> H%J B UGY pG8�2XHt>72o> pZ:6JWR=<g:=< 84 :6J`J4d :6J�< > BD2 rG:o@g@g> �]2o> :6JWJ : LZ6 B q : :cb 8 6 B @�R6J�<g: � � = ; 8�pXB 8�2o8 8 @ 8_H%RABg<g:@g>%J > J4d B @�< 6)R 5B >�258 :o@g@g> : B :=<g:�Z ?I8 <hRf<~< 8 J 8 8 @�LZ698 @g@CB >72AB.@g>�2o> � ; � '�pXB 8�258�8 @ 8_H%RABg<g:0J4d B @�< 6)R 5B >�258 :cb 8.@ 8�HMR58jJ4dsRNJ�< B q > L2G�TXL �7@ 8 �8 LZ698�@ 8�2=< 8 �:6J�< 6 BDq 8�2=<`B 258�@g@�RK2i: 4K8cJWJ 8 B @�< 6)R 5B >�2AB pXB 8�2o8�8 @ 8�HMRAB < :�Z0�@fZ 8$UVF a U � �!1 3 � � 1 5 !

UGY � U � 3 �5 � � !

L2G�TXL UGY � 3 � U �5 � � !

L2G�TXL5 � �"!

� ¢{�I�����¥��¦�� § �

Page 20: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*^/ T5h U5al^ b 8 J :�@CBD2=<g:o@g@CB �8jJ : @ 8_H%R58�2=< 8

T5h U5al^ b � $ � � � $ � � � � � $ � �^XE�TXL � � � � � � � $ & d

� ���'� �����'� �#�!$ & �� P J�LME#5 ! �

^XE�TXL � � � � � � � $ * d� ���'� �����'� �#�!$* �� P J�LME#5 ! �

,,� HILtYIEG\KG�a d �

� ���'� �����'� �#�!$ �� P J�LME#5 ! �

4X>ZpG8 $ � � � $ � � � �#�!$ 8 � � �'� � � � $ & ( � � �'� �?� � $ * (������ @g>72o> : p�:NJ > 6 B ^ b E�J> UVF a Z BsJ pZ:6J >M698 4IB $ � � � $ � � � � �!$ pXB 8�258 : >�2=e 6 >72=<g:=< > BD2 @�R :�: 8�@g@CB >72o8: >�2 J 8 � � �'� � � � � @�Lt8 : B�� : :=< 8 4X>%L�> ^XE�TXL D UFRi:K254A> $ � � � $ � � ���#�!$ �8RXH%Ri:6J 8 : RK2G: � � �'� �?� � $ � pi8Z2XHA>�2o> 8 @ 8�HMRAB </8 BD2 @ 8�UMR58�2 : < R=<~< 8 J 8B @�< 6)R 5B >�2AB�: LG:Z6I< B 69834 :"UFR58cJ`J : :o@g@g> : B :f< : :6JWJ : � � � � � � � $ �?2;>�:NJWJ : LZ6 B q :B @�< 6)R 5B >�258 P J�LME#5 BD2 : >�2=< 6 :=<g: > �?2o> :NJWJ : �?258 4K8kJWJ : T5h U5al^ b Z ?I8258 @g@�RX2 : >�2=e 6 >�2=< > b :�@�R :�: 8�@g@g> pXB 8Z258 8 @ 8_H%RABg<g: J d B @�<C6zR GB >7258�:;@g@g> : B :=<g:: HILtYIEG\KG�a ��@ 8 8 @CB @�< 8 ��:NJ�<C6 BDq�8�2=<`Bt2o>�2�pXB 8�2o8 8 @ 8_H%RABg<g:�258 @g@�RX2i: : 5B >�258NZ

� ¢{�I�����¥��¦�� §

Page 21: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

0�@fZ 8 LGFM\�� J �AP � J�R�TMTXR 1 P L�J HIL 1 PKGG\ � ^XR2GMR�J�L � PKGG\ !T5h U5al^ b � ^XR2GMR�J�L � �^XE�TXL J�R�TMTXR d

^XR2GMR�J�L � P L�J HIL !P J�LME#5 !

^XE�TXL P L�J HIL d^XE�TXL PKGG\ d

^XR2GMR�J�L � J�R�TMTXR !P J�LME#5 !

^XE�TXL HILtYIEG\KG�a dP J�LME#5 !

� ¢{�I�����¥��¦�� � �

Page 22: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*^/ YIR�J98 J :�@CBD2=<g:o@g@CB �8 J :�@ 8_H%R58�2=< 8

YIR�J � � �/� � ��� ��� � � ��� ��� � �!$ � ! � � �#� � ��� �#�!$ � ! � �.� ��� $'"%$�� � � � ���� � ������� �#�!$

4X>ZpG8 �.� � ��� � � � � � � �'� �#�!$ ( � � � � �����#�!$ ( �.� ��� $'" $'� � � @g>72;> � � = � � 8 9� 8 ZB 2AB 5B :6J q�8�2=< 8�pXB 8�258�8 @ 8�HMRAB < : J d B @�<C6zR GB >7258 �.� � �'� ��� � � � ����� � � $ D �,@ 8 : d �8�� �UFRAB 254�B pXB 8Z258 p�:NJWR=<g:=< : � � � ?� ��� � �!$ �Q@ 8 : d �8�� 8 � @ 8 �8 � � = ; �Q@ 82o>�2 : d �8 pXB 8�2o8 : >72;@CB 4K8�6 :f< : � � =�; � � pXB 8�2o8 6 B4Lt8 <hR=<g: J : @ 8�UMR58�2 :���'� �����'� �#�!$ � �.� ��� $'"%$'� � � D � � �#� � ��� �#�!$ D �]2 :cb �8 � �#� ?� ��� � � $ 6 B @�R6J�<g:� � = ; Z � d 8 @ 8 : R 5B >72o8 < 8�6,q�B 2i: 2o>72 :6L6L�8�2i: � �#� ?� ��� � � $ 6 B @�R6J < :�� ; � ; Z0�@fZ 8$UVF a U21 3 � � � 1 5 � � 1 G !

YIR�J � U � � ! � U � 3 � ��� � � � U � 5 � ! U ��� �G � � � � U !

YIR�J � ! ! �

U ��� !

� ¢{�I�����¥��¦�� ��§

Page 23: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x~n^q�!`(+*^/ h b U�GMLF8 J : @CBD2f< :o@g@CB �8 J : @ 8�HMR58Z2=</8

h b U�GML � $ � � � $ � � � �#�!$ ����'� �����'� �#�!$

?I8 $ � � � $ � � ���#�!$ �8 � � = ; pXB 8�258 6 B4Lt8 <hR=<g: J : @ 8�UFR58Z2 V: ���'� ������� � �!$ �$ � � � $ � � � � � $ D �]2 :cb �8 $ � � � $ � � � �#�!$ 6 B @�R6J�<g: � � =�; Z � d 8 @ 8 : R GB >7258@< 8�6,q�B 2i:UFRi:X254X> $ � � � $ � � � � � $ 4�B pG8�2=<g:�� ; � ; Z0�@fZ 8$UVF a U � � 1 3 � � ��� !

h b U�GML � U � 3 �U ��� !

u$]�1_x n^qc!W(5*^/ HIR � h b U�GMLF8 J :�@CBD2=<g:o@g@CB �8jJ :�@ 8_H%R58�2=< 8

HIR� �'� ������� � � $

h b U�GML � $ � � � $ � � � � � $ � !

? BDq�B J 8 : h b U�GML �%J4dsRK2tB : : 4�B��?8�6 8�2 : �8 :cb 8 $ � � � $ � � � � �!$ pXB 8�258�pZ:6JWR=<g:=<g::6JWJ : �]258�D0�@fZ 8$UVF a U � � 1 3 � � ��� !

HIRU ��� !

h b U�GML � U � 3 � !

� ¢{�I�����¥��¦�� � �

Page 24: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*%! �V(+. #M(�]�1�/ 8 @CBD2=<g:=<>< B : :Kq�8�2f</8)8�UFRAB p�:NJ 8�2=<`B :6J`J 8 B @�< 6)R 5B >�2AB�,@ 8�q L6J B : B � e > 6Qq :=< 8�4 : 8 @�LZ698 @g@CB >�2AB 8Y< 8�6,q�BD2G:=</8�4 : d ! d ��J 8 8 � = � >#8 9� 8���� � � � @g>72o> e > 6,q :f</8 4 :�LAB��R$4�B :kb B :Z6 : 5B >�2ABX8.B @�< 6)R 5B >�2AB�@ 8�q L6J B : Bt>:OJ > 6 > pG>%J�<g: : >7q LZ>A@�< 8 �]6 : :�:kb B4Ro@ 8 e 6 :OLi:Z698Z2=</8�@CB^H�6 : �]8 � �

����'� ���������#�!$ &���'� ���������#�!$ *

ZZ�

78Z6]8�@ 8�q LAB >�J d B @�<C6zR GB >7258 YIR�J L6R �> 8 @g@ 8�698!6 B @ : 6 Bg<~<g:�Ro@ :K254A>�J : h b U�GMLF8

YIR�J � � �/� � ��� ��� � � ��� ��� � �!$ � ! � � �#� � ��� �#�!$ � ! � �.� ��� $'"%$�� � � � ���� � ������� �#�!$

�8�8�UFRAB pZ:6J 8�2=< 8!:

�.� � ��� ��� � � � ����� �#�!$ �

h b U�GML � � �#� � ��� �#�!$ � ���� � ������� �#�!$�.� ��� $'"%$'� � � �

� ¢{�I�����¥��¦�� � �

Page 25: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*^/ P J�LME#5|8 LZ6 >ZpG> : : J4dsRo@ : Bg< : BDq�q 8 4�B :=<g: 4 : T5h U5al^ b 1YIR�J)1 h b U�GML 1 HIR � h b U�GML D J4d 8�@ 8 : R 5B >�258 : >72f< BD2NRi: 4M:6JWJ4d B @�< 6)R 5B >�258@�R :�: 8 @g@CB pZ:�Z0�@fZ 8$UVF a U21 3 � � � 1 5 !

YIR�J � U � � ! U � � ��� ! U ��� � �UGY � U � � � � 3 � P J�LME#5 !5 � U ! S�S 8 @ 8_H%RABg<g:�@g>%J >-@ 8 U �8#q�BD2;> 698.4�B%� s

u$]�1_x n^qc!W(5*^/ ^XRGF a UVFM\SLF8 258iB : B : J B h b U�GML 1 HIR � h b U�GML Lt8�6,q 8�<~< 8�698!4�BLi:o@g@ :Z6 8 4�BD698�<><g:Kq�8�2=< 8 :6JWJ : @�R :�: 8 @g@CB pZ: 8 @ 8 : R 5B >72o8 4�B $ � � � $ � � � �#�!$ D@ :6J�<g:K254A> J 8 B @�<C6zR GB >72AB BD2=< 8�6,q�8 4IB 8 � 258cJ : B : J > YIR�J 4�B Li:;@g@ :Z6984�BD6 8�<~<g:Kq�8Z2=</8e:NJWJ : @�R : 8 @g@CB pZ: 8 @ 8 : R GB >7258+4�B �.� ��� $'"%$�� � � D � � �#� � �'� �#�!$ D@ :6J�<g:K254A> J 8�B @�<C6)RGB >�2ABSBD2=< 8�6,q�8 4�B 8NZ0�@fZ 8$UVF a U � � 1 3"!

h b U�GML � U � � ��� � �U ��� !UGY � U � � � ^XRGF a UVFM\SL !3 � U ! S�S 8 @ 8_H%RABg<g:�@g>%J >-@ 8 U �8�4�B @�LG:Z6 B

� ¢{�I�����¥��¦�� ��B

Page 26: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u$]�1_x n^qc!W(5*^/ ��R�a�RF8 L�8�6,q�8 <~< 8 4�B Li:o@g@ :Z698 :6JWJ4d 8�@ 8 : R 5B >�258 4�B RX2i:UFRi:NJWRK2TUFRo8 :6J�< 6 : B @�<C6)RGB >�258 :NJWJ4d BD2=< 8�6,2;> 4X8cJWJ > @�< 8 @g@g> � q�> 4MR6J > 4�B��LZ6 >�H76 :Kq�q : :cb 8+@CB :YLZ698 : 8 4MR=< : 4 :YRK2i: � ; � ��� �A8 : B > �8 RK2.B 4K8�2f< B�� : :=< > 6 8pZ:6J B 4A>�@ 8_HMRtBg< > 4M:6J : :Z6 :=<></8�6 8 � d ��Z � :!@CBD2=<g:o@g@CB �8

��R�a�R � �� $ � !

1 � � 0 ��� B � � 0 8 J d B @�<C6zR GB >7258 ��R�a�R �8 RK2 8cJ 8Zq�8�2=< > 2o>�2 258 : 8 @g@ :Z6 B >:6JWJ : LZ6 >�H76 :Xq�q : 5B >�258 � 8 4 �8 B 2 : >�2=<C6 :o@�< > : >�2 B J LZ6 BD2 : B4LAB > :6JWJ : rG:o@ 84K8cJ`J :�LZ6 >�H�6 :Kq�q�: GB >7258.@�< 6)R=<><hRK6 :=< : �0�@fZ 8$UVF a U � � 1 3 � � �"!

h b U�GML � U � � ��� � �U ��� !UGY � U � 3 � ��R�a�R Tia�RGc !

�Tia�RGcedU � 3 � � !

� ¢{�I�����¥��¦�� � #

Page 27: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� �V(5#M( ,%/\3{3`/ y�-2x~!`-%t%!s34! 8 BD2 HX8�2o8�6 :6J 8 <hRf<~< 8 J 8 p�:Z6 B :KrAB4J B b :K2K2o> RK2o>'�� � .:;@g@g> : B :=< > :cb 8�258 4K8�< 8�6,q�BD2i:�J : pXBg< :$8�698_Ht>MJ : B J q >�4X>-BD2 : RAB�J 8pZ:Z6 B 8�Li:Z6I<`B 4K8kJTLZ6 >�H�6 :Kq�q :�L�>t@g@g>�2o>�: :�: 8 4K8�6 pXBsZ � 8cJ : :o@g> 4�B 8 � = � >#8 9� 8���� � � � � J > '�� � 4�BjRK2G: p�:Z6 B :KrAB4J 8 B pXB.4K8 �]2ABg<g: �8 J4d B @�< 6)R 5B >�258@�< 8 @g@ :�� J : pZ:Z6 B :KrtB4J 8 BD2tB GB : :54 8 @CB @�< 8�698 UFRi:K254A> J : 4�B :kb B :Z6 : 5B >�258pXB 8�258 8�@ 8_HMRtBg< : 8 : 8 @g@ : 4�B 8�@CB @�</8Z698 UFRi:X254X> < 8�6,q�BD2i: J4d 8�@ 8 : R 5B >�2584K8cJ`J4d B @�< 6)R 5B >72o8 : >�q L�>t@�<g:�Z B 2o>MJ <C698 J : p�:Z6 B :KrAB4J 8 �8 : :�: 8 @g@CBDrtB4J 8 @g>MJ >:6JWJ d BD2=< 8�6,2o> 4K8cJWJ d B @�<C6zR GB >7258 : >7q LZ>A@�<g:�� 4 : : RAB B4J 2;>7q�8 4�B�� ;+=�8<; �98 � �� � ; � �XZ0�@fZ 8$UVF a U � � 1 5 !

UGY � U � �UVF a 3"!3 � � � U !

�5 � 3 � �"! S�S 8�6,6 > 698 � 3 UMRAB 2;>72�8-2;>�<g: ���

� ¢{�I�����¥��¦�� � �

Page 28: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ��� �����������

� nM*21�-61w(%x~! 8 @g>�2o> pZ:Z6 B :KrAB4J B :cb 8 : >72=< 8�2XHt>�2o> B 254�BD6 B� 5B[4�Beq 8�q > 6 B :�Z�O:K2K2o> RK2 � 8 � ��; '��:o@g@g> : B :=< > :cb 8 �8#B4J^<`B4L�> 4K8cJ 4M:=< > q�8�q�> 6 B :=< >:6JWJ d BD254�BD6 B > : >72=< 8�26Rf< > 258cJ5L6RK2=<g:=< > 698 8 @CB9Li:Z6)J :�UFRABD254IB74�B'L6RK2f< :=< > 6 8: RK2 : 8Z6I< > <`B4L�> 4�B�4 :=< > �!4X>Zpi8 B J < B4LZ> L6R �> 8 @g@ 8�6 8 RK2o> 4K8iB < B LABe >�254 :Kq 8�2=<g:6J B > �9LAB��R BD2 HA8�258Z6 :6J 8 ��UFRi:NJ @CB :o@CB : >A@ : :KrXrAB :ORK2)BD2o4�BD6 B >5Z� 2i:�pZ:Z6 B :KrtB4J 8 L6RK2=<g:=< > 698�: � ����� @CB 4IB :cb B :Z6 : : >�q�8 8

� ������� � ��� � � � �� $ � � ����� �� $ �

4X>ZpG8 � � � � ��� ��� $ �8�B4JI2o>�q�8 4K8cJWJ :�pZ:Z6 B :XrAB4J 8NZ � 2 LNRK2=<g:=< >M698�L6R��> 8 @g@ 8�6 8BD2AB�GB :NJ B V:=< > 8 � : >�2VpG8�2 5B >72G:6J q�8�2f</8 � RX2 L6RX2=< :f< >M698 B 2AB 5B :6J B :=< > : s> � � ��� 2o>�2 LNRK2=<g: : 2AB 8�2=< 8NZ � 2 L6RK2=<g:=< > 698 : P RIUGH 2o>72 b : RK2Li:Z6I<`B : >%J :Z698 <`B4L�> ri:o@ 8 :o@g@g> : B :=< > � L6R �> L6RK2=<g:Z698 : UFRi:6J @CB :o@CB�<`B4LZ> 4�B4 :=< >KZ0�@fZ 8$UVF a � c UVF a � � � ��� !

Y�GMRME�a � c Y�GMRME�a !P RIUGH � c P RIUGH !LGFM\�� J �AP � J�R�TMTXR 1 P L�J HIL 1 PKGG\ � !J �AP � c J �AP !

� �¦ �$���{�>�}� � �

Page 29: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� #M/�x)-61w(%x~! � / � 8 : >�q�8 @ :6L6LtB :Kq > B4J 2o>�q�8 4K8cJWJ 8 pZ:Z6 B :KrtB4J B �]2o>M6 :BD2 : >72=< 6 :=< 8 �8 :o@g@g> : B :=< > :NJ pZ:6J > 6 8 � : >72f</8�2NR=< > � 4K8cJ`J : pZ:Z6 B :KrAB J 8�D�L�8�6:VpG8�698�B4J�J > 6 >)BD254IBD6 B �> BD2�q�8�q >M6 B :.@CBK:6L6L6J B : : J d >ML�8�6 :=< > 698 RK2i:Z6 B > � BD2e >M6,q : LZ6 8 �I@g@ :!:6J�2o>�q�8 4K8kJWJ :$pZ:Z6 B :XrAB4J 8 � � ��� � � ��'� � $ Z � d :6J�< 6 > : :K2=< >)B4J: >�2=< 8�26R=< >�4�BQRK2 L6RX2=< :f< >M698 �8 RK2 BD254�B 6 B �> 4�B q�8�q >M6 B :��'Lt8�6 :VpG8�698 B4JpZ:6J >M698 q�8�q >M6 B V:f< >�: <g:6J 8 B 254�BD6 B� >�@CB�:6L6L6J B : :0J4d >%Lt8�6 :f< >M698�RK2i:Z6 B > �BD2 e > 6Qq :�LZ6 8 �I@g@ : :6JS2o>�q�8�4K8cJKL6RK2=<g:=< > 698 � � � ��� � ��� �� $ Z0�@fZ 83Y�GMRME�a � c Y�GMRME�a � � � ��� !

Y�GMRME�a � � � � � N������41 � � � !c Y�GMRME�a � ��� !� � � c Y�GMRME�a ! S�S � b :!pZ:6J >M698 � � � N������� c Y�GMRME�a � � � N � !� � � c Y�GMRME�a ! S�S � b :!pZ:6J >M698 � � N �

1 � � 0 ��� B � � 0 8 J dsRo@g>-4�BKRX2 L6RK2=<g:=< > 698 :cb 8 : >�2=< B 8�258�RK2#BD2o4�BD6 B > 4�Bq�8�q�> 6 B : 2o>72 pZ:6J B 4X> LNR��> LZ6 >Zp5> : :Z698-8 �]8�<~<`B�BDq LZ698 pG8 4�BDrtB4J B$DaL6R �> 2o>�24 :Z698�:6J : RK2jLZ6 >7r6J 8�q : : >A@ � � : >�q�8�L6R��>�LZ6 >�p5> : :Z698�J4d :Z6,6 8 @�< > B q LZ6 >ZpopXB @g>4K8cJ"LZ6 >�H�6 :Kq�q : > :6J�< 8�6 :Z6,258 BD2 q :K2tB 8�6 : BDq LZ6 8 pG8 4�BDrAB J 8 B+4 :f< BsZ �08 @g@ 8�2GB :NJ 8 : >�2=<C6 >MJWJ :Z698 : :�: RX6 :=<g:Kq�8�2=< 8 J : pZ:6J B 4�Bg< �: 4K8_H%J B BD254�B 6 B GB:o@g@ 8_H�2i:=<`B :AB+L6RK2=<g:=< > 6 BsZ

1 � � 0 ��� B � � 0 8 B J � 8 � ��; '� 4�B RK2 L6RK2f< :=< > 6 8 �8 RX2 8kJ 8�q�8�2f< >BD254IB @�Lt8�2;@ :KrAB4J 8 Lt8Z6 :cb �8 Lt8Z6,q�8�<></8 :NJ : >7q LtB4J :=< > 698 4IB : >72o>t@ : 8�6 8 J 8: :Z6 :f<~< 8�6 B @�<`B :cb 8 4X8cJ <`B4LZ> 4�B 4M:=< > : : RAB B4J�L6RK2=<g:=< > 698 e : 6 Bge 8�6 BDq�8Z2=< >

� �¦ �$���{�>�}� � �

Page 30: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� J : 4�BDq 8�2o@CB >�258 � Lt8�6#8�@ 8�q LAB > � Z B 2 HX8�2o8�6 :6J 8 RK2 L6RK2=<g:=< > 698 4K8 pG88 @g@ 8�6 8 R=<`B4J B :=< > BD2 q�:K2AB 8�6 : : >�2o@CB @�< 8�2=< 8 : >�2 B4J @�Ro> < B4LZ> rG:o@ 8 8 B4J: >�q LAB4J :=< >M698 : Bi@ 8_H�2i:6J :$:6J : RK2o8 4K8cJWJ 8YLZ>A@g@CB rAB4J B BD2 : >72o@CB @�</8�2 8 �lq : 2o>�2@ 8 Ro@CB :Kq > B4J � ; �>Z0�@fZ 8$UVF a � c UVF a � � � ��� !

Y�GMRME�a � � � � � N������41 � � � !c UVF a � ��� ! S�S 8�6Q6 > 698 � � � > 258kR=<C6 :6J B �> : >�20RK2 : :o@�<�ZEZEZc UVF a � � UVF a � � ��� ! S�S B4J : >7q LtB4J :=< > 698�2o>�2 4 : 8Z6,6 > 6 8#q�: ZEZEZ� � � c UVF a ! S�S B4JS6 B @�RNJ�< :f< > �8 : RK6 B >A@g> ���

� x~!}1_.0/�1�!��V- �V(+* !�#MnM*21�-61w(%x~! 8@: >�2)BQL6RK2=<g:=< > 6 B��8 L�>t@g@CBDrAB J 8�8 @ 8_H%RABD6 8@g>%J > :6J : RX258!4K8kJWJ 8.>ML�8�6 : 5B >�2AB7:Z6 B <Cq�8 < B :kb 8NZ B 2OLi:Z6I<`B : >%J :Z698 �8 LZ>A@g@CBDrtB4J 8@g>�q�q :Z698 > @g>�<><C6 :Z6,698 4M: RK2 L6RK2=<g:=< > 698 RK2i: : >A@�<g:K2=< 8 UVF a �+> e :Z698J : 4�B��]8�698�2 : e 6 : 4FRo8 L6RK2=<g:=< > 6 BjL6RK6 :cb �8 @CB :K2;> 4K8cJWJ > @�< 8 @g@g> <`B4L�>ri:o@ 8�Z � 8cJ"LZ6 BDq�> : :o@g> � �� � ; � � =�;�>?8 � � 7 8 ��� ; �' � ; � � � �J4d BD2o4�BD6 B > 4�B q�8�q�> 6 B : :o@g@g> : B :f< > :6J�L6RK2f< :=< > 6 8�pG8�6,6 �: BD2 : 698�q�8Z2=< :f< >> 4K8 : 698Zq�8�2=<g:=< > 4IB�RK2 pZ:6J >M698 Li:Z6 B :NJ;LZ6 >�4X>c<~< > 4K8cJWJ : : >A@�<g:K2=< 8 L�8�6J : 4�BDq�8Z2o@CB >�258.4K8cJN< B4LZ> ri:o@ 8�Z � 8kJK@ 8 : >72o4X> : :;@g> � 7 8�� � = ��� >�; � =�; 7 ���� ����� ; � = 8 � ��J :-4�B��]8�698�2 :je 6 :jH%J B BD254�BD6 B 5B 4IB�q 8�q > 6 B : : >�2=</8Z26R=<`B�2o8iB4FR58 L6RK2f< :=< > 6 BMpXB 8�2o8�4IB pXB @ : L�8�6 J : 4�B q�8�2o@CB >�258�4K8cJN< B L�> ri:;@ 8NZ

� �¦ �$���{�>�}� �

Page 31: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

u¤3�.0(+,5! � �V-61�(%x)/ ,5! - � �V/N] ] ( ^XRGF Tia98 258cJ : :o@g> 4�BL6RX2=< :f< >M6 B @g>72o>L�>t@g@CBDrAB J B @CB :OJ : 4�B :cb B :Z6 : 5B >�258 � � � � � ; �� = � ; �� � ; � � � �

^XRGF Tia � ����� � � ��� � � � �� $ � � ����� �� $ �

:cb 8 Lt8Z6,q�8�<></8)4�B : :Kq�rAB :Z698 J4d B 254�BD6 B� > : >72=< 8�26Rf< > BD2 � ��� � � � �� $ q :2o>�2 B4J pZ:6J > 698 : : RAB�L6RK2=<g:�� :kb 8 J :�4IB :cb B :Z6 : GB >7258 � � ��� � ; � = � �' � ; � � � �

��������� ^XRGF Tia � ��� � � � �� $ � � ����� �� $ �

:cb 8 Lt8�6Qq�8�<></8 4�B : :Kq!rAB :Z698 B JOpZ:6J > 6 8 : : RAB L6RK2=<g: � ��� � ��� �� $ �!q :2o>�2 J4d BD254�B 6 B �> : >�2=< 8�26R=< > B 2 � � � � � � ��� $ Z �0 :X2 :cb 8 LZ>A@g@CBDrtB4J 8 J :4�B :kb B :Z6 : 5B >�258

^XRGF Tia � ������� ^XRGF Tia � ��� � ��� �� $ � � ����� �� $ �

0�@fZ 8$UVF a U � �!1 3 � � 1 5 � � !^XRGF Tia UVF a � c UVF a � � � ��� !UVF a � ^XRGF Tia c � UVF a � � 5 !c UVF a � � U !� c � UVF a � 3"!

� �¦ �$���{�>�}� � �

Page 32: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� nM*21�-61w(%x~! - #MnM*21�-61w(%x)/ 8 �8 LZ>A@g@CB rAB4J 8 4IB :cb B :Z6 :Z698 RK2 � ��� � ; � = � ;� ����� ; � = �YR;@ :K254X> J : 4�B :kb B :Z6 : 5B >�258

� � � � � � � � � � ��� ��� $ � � ��� � ��� $ �

4X>ZpG8 � ��� � � � �� $ �8 RK2 L6RK2f< :=< > 6 8 4�B�L6RK2f< :=< > 6 8 : ������� Z 6 R58 @�<g:4�B :kb B :Z6 : 5B >�258 �8eBD2�6 8;:6J�< �:�B 4X8�2=<`B : :3:UFR58kJWJ : 4K8kJrL6RK2f< :=< > 6 8 �,@ 8�q L6J B : 8�� 8BD2=< 6 >�4X>c<~< > B4J 26Ro>Zp5> <`B4LZ> � ����� ; � = � ; � � � � � � � ���?� ������� � � ����� � �:KrKrtB :Kq > BD2=e :=<><`B � � ��� � ��������� � ��� � � � �� $ � � ��� � ��� $ � Z � @g@ 8Z6 pXB :Kq >: >�q�8 � � � � ��� ��� $ @CB : 4�B�<`B4L�> L6RK2=<g:=< > 698 � � � ��� � � � �� $ @CB : :X2 : > 6 : 4�B<`B4L�> L6RX2=< :f< >M698 �I8 ��� � � � � � � ��� $ @CB :�BD2VpG8 : 8�4�B2<`B4L�> ������� Z0�@fZ 8 a��AcSLtHILtY UVF a � � UVF a !

� UVF a c UVF a � � � ��� !� UVF a � c c UVF a � � � ��� !UVF a U � � ��� 1 3 � � !c UVF a � � U !c c UVF a � � c UVF a !3 � ��� c c UVF a ! S�S 3 b :!pZ:6J > 698 � sts Z

� �¦ �$���{�>�}� ��§

Page 33: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� 3{3`( �V-2q�!`(+*^/ ,5!$*^-%. !��V- 8 J4dsR;@g> 4K8cJWJ 8�pZ:Z6 B :XrAB4J B 2o>�2 �8 B4J q�8 < >�4X> LAB��R� 8 @g@CBDrAB4J 8 Lt8�6 J : q 8�q > 6 B : 5B >�258 4K8iBO4 :f< B BD2 q 8�q > 6 B :�Z B 2=e :=<><`B J :q�8�q�> 6 B : :;@g@ 8_H72G:=< :!: RK2i:�pZ:Z6 B :KrAB J 8�pKB 8�258 � @g@ :=< : :NJ7q >7q 8�2=< >-4K8cJ`J :: >�q LAB4J : GB >7258 8 2o>�2 L6R��> 8 @g@ 8�6 8 q >�4�B�� : :=<g: 4FRX6 :K2=< 8 J4d 8�@ 8 : R 5B >�258NZB 2o>%J�< 698 �S@ 80RK2i:�p�:Z6 B :KrAB4J 8=2;>72 @ 8Z6 pG80LAB��R 2o>�2 �80LZ>A@g@CBDrtB4J 8 : :K2 : 8cJWJ :Z6zJ :��rAB @g>�H�2i: :=<>< 8�258�698 :cb 8 pZ:54 : �.�# =�8 '�� � 8 : B �> LZ>�< 698�rKr�8 :Vp;pG8�2AB 698:K2 :kb 8 :NJWJ : �]258)4K8cJ LZ6 >�H�6 :Kq!q :�Z �8�6 >Zp;pXB :Z698=: UFR58�@�</8 J BDq�B < : 5B >�2ABB4J @CB @�< 8�q : >ML�8�6 :=<`B p5> q�8�<></8 : 4�B @�L�>t@CB 5B >�258 J 8 �.� � >?8 � 8 4IB � 8 �?= � =�8<;� E2G2GMR�^ ��� 8 YKJ�LML ��� � 2o>�2 e :K2X2o> Li:Z6I< 8#4K8cJ�J BD2XH%Ri:XH�H B > � q�:)4�B RX2i:� 8 �?= � =�8<; 8 @�</8Z6,2i: � :kb 8 L�8�6,q�8 <~< >72;> 4�B :NJWJ > : :Z698 8 J BDrt8�6 :Z698 q 8�q > 6 B :UFRi:X254X> : 8 2^d �8 rtB @g>�H�2o> � ; � � � ;�>#8 9� � 7 8 � ; � 8 � ; ��Z � : @CBD2=<g:o@g@CB 4K8cJ`J 8:cb B :Kq :=< 8 �8 J :�@ 8_H%R58�2=< 8 8

� � � � � � ��� $ � � � ����� � � � E2G2GMR�^ � ���� $ �^D

YKJ�LML � � � � � � � ��� $ �^D

4X>ZpG8 � � � � ��� ��� $ �8 RK2 LNRK2=<g:=< >M698#: ������� 8 ���� $ �8)B4J 26RKq�8Z6 > 4�B r��X< 84 : :6J`J > : :Z698NZ BsJ � ; � �8 258 : 8 @g@ :Z6 B > L�8�6 :cb �8 � E2G2GMR�^ 698�@�< Bg< RAB @ : 8 RK2L6RK2f< :=< > 6 8!: P RIUGH Z� #M/�x)-61w(%x)/ T�U��ILMRtYQ8 698�@�< Bg< RAB @ : 8 J : 4�BDq 8�2o@CB >�258 B 2 r��X</8 4�B RK2UFRi:NJ @CB :o@CB^< B4LZ>�4�B 4 :=< >-> 4�B+RK2i: UFRi:6J @CB :o@CB pZ:Z6 B :XrAB4J 8

T�U��ILMRtY �� � � ��'� � $ D

� �¦ �$���{�>�}� � �

Page 34: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

T�U��ILMRtY � ������� �^D

� 8cJ?@ 8_H%R58�2f</8)8 @ 8�q LtB > pKB 8�258 :NJWJ > : :=<g:cSG4K8;:6JWJ > : :=< : q�8�q�> 6 B : Lt8�6 � sBD2=< 8�6 B0�@fZ 8$UVF a � c UVF a !

c UVF a � � UVF a � � � E2G2GMR�^ � � � � T�U��ILMRtY � UVF a � � !YKJ�LML � c UVF a � !

� 1w- ��� / p^/�-%# 8 B4JOq >�4X> BD2 : RAB B�4 :f< B pG8�2=HA>�2o> BDq�q :XHK: GB 2i:=<`BOBD2q�8�q�> 6 B :�4IB4Lt8�2o4K8 4 :6JT<`B4L�>!4�BA:6JWJ > : : 5B >�258NZ � :�q 8�q > 6 B : Lt8�6 : >t@�<g:K2=<`B8 p�:Z6 B :KrAB4J B B4J : RAB @ : >%L�> �8 J4d BD2=< 8�6 > LZ6 >�H�6 :Kq�q�:�pXB 8Z258�:NJWJ > : :=<g:-BD2 e :o@ 84�B : >�q LAB4J : GB >7258 �,8 @CBN< 6 >Zp�:�@�RXrABg< >-4X>%L�>=B4J : >�4�B : 8$4K8kJMLZ6 >�H�6 :Kq!q : � Z� : q 8�q > 6 B : Lt8Z6lJ 8=p�:Z6 B :KrAB4J BaJ > : :6J B pXB 8�258 :NJWJ > : :=<g:���UFRG:K254X> UFR58 @�< 88�2=< 6 :K2;> BD2 @ : >MLZ> � @�RNJWJ > � ; ��� :kb 8 �8 RK2i: @�< 6)R=<>< RK6 : 4�B <`B4LZ> ������� � ; � � 8 � @ = � � ���� 8 J4dsR6J�<`BDq > 4M:=< > :cb 8 8�2f<C6 : �8 B4J"LZ6 B q > : Ro@ : BD698�� Z� :#pZ:Z6 B :KrAB J B pG8�2XHt>72o> 6 B q >A@g@ 8#4 :6JWJ > � ; ��� 2o>�2 :6LNLt8�2i:#pZ:K2K2o> e~Ro>M6 B@ : >%L�> �$BD2 > 6 4�BD258 BD2VpG8�6 @g> : UFR58cJWJ > 4�B3BD2;@ 8�6 BDq�8Z2=< >KZ � d :NJWJ > : : 5B >�2584�BD2G:Kq�B : :��3B 2VpG8 : 8 � Ro@ : J : LZ6 BDq�: >72G: 4IB�q�8Zq > 6 B : J BDrt8�6 : LZ698�@ 8�2=< 8258cJ`J4d : � ; � �FRK2G: @�<C6zR=<~< RK6 :�B4J : RABZ: :�: 8 @g@g>#2o>�2 �8.6 8_HA>%J :=< >�4 : RK2 LZ698 : B @g>> 6 4�BD258 : >�q�8�258cJ : :o@g>�4K8kJWJ > � ; ����Z

� �¦ �$���{�>�}� � �

Page 35: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� �������M�����������k� ���� � ���E��

� x xz-�� 8 RK2 ;+= = ;�� �8 RK2 BD2o@CB 8Zq�8 4�B]p�:Z6 B :KrAB4J B�4K8cJWJ > @�< 8 @g@g> <`B4L�> : : RAB�8 :o@g@ 8_H�2i:=< > RK2 RK2AB : > 2o>�q�8 � > 694�B 2i:=< 8 RX2i: 4IB @ 8_H%RABg< > :NJWJ4d :6J�< 6 : 8B 4K8Z2=< B � : :f</8.4 :ORK2o>�> LAB��R 8 � 7 8 � 8 BD2=< 8�6 BsZ�+B :cb B :Z6 : 5B >72o8 8

� ����� �!�#"%$ � ?�."%$�� � ���#�!$ & � � ?�."%$�� � ���#�!$ * � ����� � ?�."%$�� � ���#�!$�� �+D

4X>ZpG8 �!�#"%$ �8 RK2 :Z6,6 :�� �� 4�BDq 8�2o@CB >�2i:6J 8 4�B 8kJ 8�q�8�2f< B 4�B�<`B4L�> ������� Z �/" $'� � � � � $ & � �/" $'� � � � � $ * � � ��� @�L�8 : B�� : :K2;> B J�26RKq�8Z6 > 4�BK8cJ 8Zq�8�2=<`B4K8cJ`J : LZ6 BDq :�� @ 8 : >7254M:�� ����� 4�BDq 8�2o@CB >�258 � B4J�LZ6 >�4X>c<~< > 4X8cJ 2NRKq�8�6 > 4�B8cJ 8Zq�8�2=<`B34�B <hRf<~< 8 J 8 4�BDq�8Z2o@CB >�2AB �8 B J�26RKq 8�6 > < >c<g:6J 8 4IB38cJ 8Zq�8�2=<`B4K8cJ`J4d :Z6,6 :��=Z 78Z6!: :�: 8 4K8�698 : RX2 @CBD2XHt>%J > 8cJ 8�q�8Z2=< > 4IB RK2 :Z6,6 :�� � �4�BDq 8�2o@CB >�2i:6J 8 �8 258 : 8�@g@ :Z6 B > @�L�8 : B�� : :Z698 J : LZ>A@CB 5B >�258 4K8cJWJ4d 8kJ 8�q�8�2f< >BD2 >�H�2AB�4�B q�8�2o@CB >�2580<C6 :Xq�Bg< 8 � BD254�B : B BD2=< 8�6 B �.� � � $ & � �.� � � $ * � ����� ��.� ��� $ � �/B4J : RtBlpZ:6J >M698 pZ: 4 : s :6JIpZ:6J > 6 8�4K8kJWJ :)4IBDq�8�2o@CB >7258�4�BDq RtBg< >4�BQ� � 8 � � � � � � �.� � � $'& � � �.� � � $ * � ����� � �/� ?� � $ � �QZ

1 � � 0 ��� B � � 0 8 258kJ : :o@g> 4�B RX2 :Z6,6 :�� B4J 2;>7q�8 e : 6 Bge 8�6 BDq�8Z2=< >:6JWJ d BD254�BD6 B > BD2 q�8�q�> 6 B :-4K8kJ9LZ6 BDq > 8kJ 8�q�8�2f< >=4K8cJWJ4d :Z6Q6 :�� � 2;>72�:6JI@�Ro>pZ:6J >M698NZ B 2 :NJ�<C6 BN</8�6Qq�BD2AB�� B4J72;>7q�8$4X8cJWJ4d :Z6,6 :���8�RK2 LNRK2=<g:=< >M698 : >t@�<g:K2=< 8:6J[@�Ro> LZ6 BDq > 8kJ 8�q�8�2f< >KZ �+B : >�2o@ 8_H%R58�2V: 2o>�2 �8 L�>t@g@CBDrAB4J 8 R;@ :Z698J4d >%Lt8�6 :=< >M698.4�BI:o@g@ 8_H�2i:Kq�8�2f< > ej6 :�4FR58!:Z6,6 :��=Z

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ ��B

Page 36: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

0�@fZ 8$UVF a E � � � � � � ! S�S�:Z6,6 :�� 4�BM�V��8cJ 8Zq�8�2=<`B 4�B�<`B4L�> UVF aE � � � � � � � � ! S�S�LZ6 BDq�> 8cJ 8�q�8Z2=< >E � � � � � � � � � ! S�S R6J�<`BDq > 8cJ 8�q�8�2=< >UVF a � c UVF a � � � ��� !UVF a U � � !c UVF a � E !U � � c UVF a ! S�S U�b :!pZ:6J > 698 �U � c UVF a ��� � � ! S�S U b :!pZ:6J >M698 � sU � � � c UVF a � � � � ! S�S U b :�pZ:6J >M698 � s

� /\.0(%x>!WqTqr-2qc!W(+*^/ / !$*%!Wqc!W-%34!WqTqr-2qc!W(+*^/ 8 RK2 :Z6,6 :�� � ��4�BDq�8�2;@CB >72G:6J 8�4�B4�BDq 8�2o@CB >�2AB �." & � ?�." * � ����� � �/" � �8 : >�2=</8Z26R=< > BD2 q 8�q > 6 B :@g>c<~< > e >M6,q :-4�B�pi8 <~< > 698 ��RK2�8cJ 8�q 8�2=< > 4�B @ 8�HMRAB < > :NJWJ4d :6J�< 6 >KZ � d > 694�B 258�8�4 :=< >�4 :6JWJ : e >M6,q R6J :

� � � � ?�." � � ��� � � ?�." � � �." * � �/� ?� � $ &�� ?�." � � ����� �

?�." � � �.� � � $ * � ������� �/� ?� � $ �

4X>ZpG8 ��� � �8 J : L�>t@CB 5B >�258 BD2 q 8�q > 6 B : � 6 B @�L�8�<>< > :6J LZ6 BDq > 8cJ 8�q�8Z2=< > �4K8cJ`J4d 8cJ q�8Z2=< > 4IB BD2o4�B : B�� �.� � � $ &�� � �/� ?� � $ *� ��� � � �/� ?� � $ � � Z

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ � #

Page 37: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

�0 LZ>A@g@CB rAB4J 8 BD2AB 5B :6J B :Z698 RK2 :Z6,6 :�� UFRG:K254X> @CB�4�B :cb B :Z6 : 258cJ.q >�4X>@ 8_H%R58�2=< 8

������� � � � � � � ?�." & � � ��� � �/" � � � � ����� & ( ����� * ( ����� �

4X>ZpG8 ������& ( ����� * ( ����� �8 J : J B @�< : 4�B?pZ:6J >M6 B :cb 8-pi8Z2XHA>�2o> :o@g@ 8�H72i:f< B�:Li:Z6I<`BD698 4 :6JTLZ6 BDq > 8cJ 8Zq�8�2=< >�258cJWJ > @�< 8 @g@g>�> 6 4�BD258 4�B @ : Ro@g@g>�@g>%LZ6 :�Z � 8cJ`J 84�B :kb B :Z6 : 5B >�2AB : >72 BD2tB GB :6J B V:GB >�258 �8 LZ>A@g@CBDrtB4J 8 >7q�8 <~< 8�698 J : LZ6 B q :4�BDq 8�2o@CB >�258 ?�." & �)UFR58cJWJ : LAB��R :)@CB 2AB @�< 6 : � � B J : >7q LAB4J :=< > 6 8 J : : :NJ : >%J ::6R=< >�q :=<`B : :Kq�8Z2=</8�Z�O>%L�> J4d BD2AB 5B :6J B : 5B >�2580�@fZ 8$UVF a U ��� � � � � � �!1 � 1 � 1 �)1 �41 � 1 � 1 � 1 �41 � � 1

� �!1 � � � !

B4J : >72f</8�2NR=< >-4K8cJWJ4d :Z6Q6 :�� U �8#6 :6LNLZ698 @ 8�2=<g:=< > BD2 ��H%RK6 : 4X>Zpi8 � 45d�8 � @�dI@CB6 Bge 8�6 B @ : >�2o>):=HMJ BSBD254IB : BI4X8 @�<C6 >�8�@CB 2AB @�< 6 > 8

��� ��� ��� ����� � m i �� � � � n ���� � � s ��� � m

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ � �

Page 38: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� 1�x~!$*2oQp^/ 8 @g>72o> :Z6,6 :�� 4IB2<`B4LZ> ^ b E�J :0RK2i:�4�B q�8�2o@CB >�258 B4J : RAB5R6J�<`BDq >8cJ 8Zq�8�2=< > �8 B4J : :Z6 :=<></8�6 8 ��� s � � ��� = � 8 � ; �� = � 798 � = 8 � ��; � Z 0�@CB @�< >�2o>:K2 :kb 8 @g>c<~< > e >M6,q : 4�B : >t@�<g:K2=<`B : >�q�8 @ 8�UFR58Z2 8 4�B : :Z6 :=<></8�6 B 1a?5A�BCB4K8cJ BDq�Bg<g:=< 8 4 :AB�4X>%L6LAB :6LtB : B �,8 @fZ � � 8cJ`J >�� � � 8 BD2 UFRo8 @�< > : :o@g> B4J: >�q LAB4J :=< >M698[:XH�H B4RK2=HX8�:6R=< >7q :f< B : :Kq�8�2=< 8+B4Jh< 8�6,q�B 2i:=< > 698 ��� s �EZ�B 2@e :o@ 84�BSBD2AB 5B :6J B : 5B >�258�8jL�>t@g@CBDrAB4J 8 LZ6 > : 8 4K8Z698 : >7q 8 : >72 H%J B�:NJ�<C6 B�:Z6,6 :��

0�@fZ 8�^ b E�J T ��� � � ��� � 1 � L � 1 � G � 1 � G � 1 � R � 1 � � � 1 ��� s � � !

>%L6L6RK698 �]BD2)q >�4X> LAB��R�LZ6 :f< B : > �'Ro@ :K254X> RX2i: : >A@�<g:K2=< 8 @�<C6 BD2XHK:

0�@fZ 8�^ b E�J T ��� � � � L2G2GMR � � !

6 R58 @�< > ��6 B : >M694 :K254A> UFRi:K2=< >�4K8�<>< >.: LZ6 >%L�>t@CBg< >.4K8cJt2o>7q 8 4�B6RK2�:Z6Q6 :�� ��8�8�UFRAB pZ:6J 8�2=< 8!:�@ : 6 B pi8Z698

0�@fZ 8�^ b E�J � ^XRGF Tia T � � � L2G2GMR � � !

1 � � 0 ��� B � � 0 8 @ 8 RK2i: @�<C6 B 2XHM: �8 4�B :cb B :Z6 :=<g: : >�q�8 :Z6,6 :�� �#2;>72 �8L�>t@g@CBDrAB J 8 Ro@ :Z698 J4d >%Lt8�6 :f< >M698 4�B-:o@g@ 8_H�2i:Kq�8Z2=< > e 6 : 4FR58 @�<C6 BD2XH b 8NZ� d :6J <C6 > : :K2=< > �54�B :cb B :Z6 :X254X>%J : : >�q�8 RK2�L6RK2=<g:=< > 698[: ^ b E�J 8_>%Lt8Z6 :K254X>: >�q�8�258cJK@ 8_H%R58�2=< 8.8 @ 8�q LAB >0�@fZ 8�^ b E�J � T � � � L2G2GMR � � 1 ^ b E�J � a !0�@fZ 8 a � T !

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ � �

Page 39: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

J :�@�<C6 B 2XHM: a 4X>%L�> J4d :o@g@ 8�H72i:Xq�8�2=< > : >�2=</8Z6,6 �: � � 8cJWJ > � � : >t@ � � : >�q�8 J :@�< 6 BD2XHK: T � q :�@g>MJ > Lt8Z6 :cb��8$8�2f<C6 :Xq�rt8�LNRK2=<g:K2o> :NJWJ :!@�</8�@g@ : J > : : 5B >�2584�B q�8�q >M6 B : ��8 : B >��8)@g>�2o> J : @�</8�@g@ : @�< 6 BD2XHK: ��8 2o>�2 Lt8Z6 :cb��8 �8 @�<g:=<g:8 �?8 <~< Ri:=<g: RK2i: : >MLAB : 4K8iB : :Z6 :=<>< 8�6 BsZ �8�6�8 �]8�<~< Ri:Z698 RK2G: : >%LAB : 4�B@�< 6 BD2XH b 8�8-q >MJ </8 :NJ�<C6 8!>ML�8�6 : 5B >�2ABI@�R6J`J 8!@�< 6 BD2XH b 8 �8 2o8 : 8 @g@ :Z6 B > R;@ :Z698J 8.>MLNL�> 6E<hRK2o8 �/��� >#8 � 8 4�B � 8 �?= � =�8<; Z

� x xz-�� ,5! #MnM*21�-61�(%x>! 8 �8OLZ>A@g@CB rAB4J 8�4IB :cb B :Z6 :Z698 :Z6,6 :��#4�B|L6RX2=< :f< >M6 B : >t@ � �: >�q�8$@CB^e : : >�2�<hRf<~<`B�H%J BI:6J�< 6 B2< B4LtB 4�B 4 :=<`BsZ0�@fZ 8�^ b E�J � ^XR2GMR�J�L ��� � �

� J�R�TMTXR � 1� P L�J HIL � 1� PKGG\ � 1

� !

� :!@�< 8 @g@ : : >A@ :!@CB+L6R��> e :Z6 8 R;@ :K254X> J4d :NJWJ > : : 5B >�258�4IBD2i:Kq�B : :0�@fZ 8�^ b E�J ��� ^XR2GMR�J�L � � ^ b E�J ��� � � E2G2GMR�^ � � � T�U��ILMRtY � ^ b E�J � � � !

^XR2GMR�J�L � � � � � J�R�TMTXR � !^XR2GMR�J�L � � � � � P L�J HIL � !^XR2GMR�J�L � � � � � PKGG\ � !

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ � �

Page 40: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� 1�x n21�1_nMx)/ 8 RX2i: � = ��� � � = ; �8lRK2!BD2o@CB 8Zq�8 4�BGpZ:Z6 B :KrAB J B�4K8cJWJ >�@�</8�@g@g>Y<`B4L�>>)4�B\<`B4LAB 4�B pG8�6 @CBl: : RAB �8�:o@g@ 8_H�2i:=< > RK2 RK2tB : > 2o>�q�8NZ � H�2ABI8kJ 8�q�8�2f< >�Q> q 8�q�rZ6 > > :f<~< 6 BDr6Rf< > ��4K8cJWJ : @�< 6)R=<>< RK6 :�� BD2o>%J�< 698 � �8 B 4K8�2f< B�� : :=< > 4 :RK2 @�R;> 2;>7q�8 :6JWJ4d BD2f</8�6Q2o>)4K8cJWJ : @�<C6)Rf<~< RK6 : � 2o>�2 4IBD698�<>< :Xq�8�2=< 8.pXB @CBDrtB4J 84 :6J`J4d 8 @�< 8�6,2o> � Z � 2i:�@�<C6zR=<~< RK6 : BD2 A � � �8 RK2 26R;>�p5> < B L�> 4�B 4 :f< > � :4�B��]8�698�2 : 4K8cJ%A � Z � :!@CBD2=<g:o@g@CB �8 8

TiaMJA\ ^ia � �'� ��� � � � � � � �� � � �+& �!� " $ & !� � � � * �!� " $ * !

,,� � ��� � � �'� � $ & ( �� � � ��'� � $ * ( ����� � �

4X>ZpG8 �'� ������� � � � �8�B4JA2o>�q�834K8kJWJ :�@�< 6)R=<>< RK6 :�� ������� & ( � � � � * ( ����� @g>�2o>l< B LAB4�B;4 :=<`B�� � � " $ &'(2�!� " $* ( ��� � @g>�2o>!Bt2o>7q�Bo4X8iBtq�8�q�rZ6 Bo4X8cJWJ : @�< 6)R=<><hRX6 :8 ��� � � ��'� � $ & (���� � � �'� � $ * ( ����� @g>�2o> pZ:Z6 B :Kr6J B 4�B�<`B4LZ> �'� ������� � � � Z � 8pZ:Z6 B :KrtB4J B 4�B6< B L�> � � ��� � � � � � L�>t@g@g>72o>�8 @g@ 8�6 8$4�B :cb B :Z6 :=< 8 BD2 RK2!@ 8 : >�254X>< 8�q L�>

� TiaMJA\ ^ia � �'� ������� � � � ��� � � ��'� � $'&'( ��� � � ��� � $*�( �����

B 2$q >�4X>$:K2i:6J >�Ht> �8�LZ>A@g@CBDrtB4J 8+4�B :cb B :Z6 :Z698e:Z6,6 :�� 4�BV@�< R=<><hRK6 8[>�L6RX2=< :f< >M6 B:�@�<C6)Rf<~< RK6 :�Z

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ �

Page 41: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ���]1 8 BD2 A �8 >�rKr6J BgHM:=< > 6 B > 6 B Lt8�< 8�698YJ :�Li:Z6 >MJ : :cb B :VpG8 TiaMJA\ ^ia :K2 :kb 8258cJ`J : @�R :�: 8 @g@CB pZ: 4�B :cb B :Z6 : 5B >�258

TiaMJA\ ^ia �'� ��� � � � � � ��� � � �'� � $ & ( �� � � ��'� � $ * ( ��� �

0�@fZ 8�TiaMJA\ ^ia L�TXL � c]UtR �UVF a U !Y�GMRME�a � !^ b E�J � T !

� P E�J L�TXL � c]UtR !

� -%. #%!M,5!5t%!}1 8 RK2i: � = ��� � � = ; L6R��>!8 @g@ 8�698 R;@ :=< : L�8�6 >%Lt8�6 :Z6 8�: J B pG8cJWJ >4�B^H76zR6L6LAB�4�B]rtBg<e4�B :cb B :Z6 :K254A>MJ :)258cJK@ 8_H%R58�2=< 8�q >�4X>

TiaMJA\ ^ia � �'� ��� � � � � � � �� � � � & � � � " $ & � d � � "%$�� � & !� � � � * � � � " $ * � d � � "%$�� � * !

,,� D

4X>ZpG8 � � � � & ( ������� * ( ����� @g>72;> UVF a)1 T�U��AFSLtH > \MF T�U��AFSLtH � � ��"%$ � � & (� � "%$�� ��*+( ��� � @�Lt8 : B�� : :K2o> B4JS26RKq 8�6 > 4�B rABg<e4 :)6 :XH�H�6)R6L6Li:Z6 8NZ

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B �

Page 42: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� � �V/N] ] ( -�! .0/\. t^x~!�,5! nM*^- ]�1�x n21w1�nMx)- 8 RX2i:=@�<C6)Rf<~< RK6 :�� : >7q 8 RK2UFRi:NJWRK2TUFRo8 < B4LZ> e >7254M:Kq�8�2=<g:6J 8 4�B 4 :=< > �#B 2 UFRi:K2f< > < :NJ 8 ��2o>72 b ::o@g@g> : B :f< BM4K8GB+LG:Z6I< B : >MJ :Z6 BXp�:NJ > 6 B{Dl:6J`J >-@�< 8 @g@g> q >�4X> 2o>�2 b :�@ 8�2o@g>je :Z6986 Bge 8�6 BDq�8Z2=< >#:ABt@�Ro> B7q�8�q!rZ6 BX4�B 698�<>< :Kq 8�2=< 8 �5Ro@ :K2o4X> @ 8�q L6J B : 8�q�8�2f</8�B4JJ >M6 > 2;>7q�8�Z ? >�2o> J 8 pZ:Z6 B :KrtB4J B 4�B�RK2 : 8�6I< > <`B4L�> :cb 8 :;@g@�RKq >�2o> 4X8iBpZ:6J >M6 B @�Lt8 : B � : B �_4FRK2TUMR58 UFR58cJWJ > :cb 8 p5>�HMJ B :Kq > �8 LZ>�< 8�6 : :_: 8 4K8�6 8 :ABq�8�q!rZ6 B 4IB RX2i:=pZ:Z6 B :KrAB4J 8=:6L6LG:Z6I</8Z258�2=< 8 : RX2i: : 8�6I<g: @�< 6)R=<>< RK6 :�Z �aJ B>%Lt8�6 :f< >M6 B :kb 8 L�8�6,q�8�<>< >72o> 4IB�e :Z698�UFR58 @�< > @g>72;> N 8 � � Z � : @CBD2=<g:o@g@CB�8 4�B pG8�6 @ :�:�@ 8 : >7254M: :cb 8 @CBA:KrKrAB :�: :cb 8�e :Z698 : >�2�RK2i: pZ:Z6 B :KrAB J 8 > : >�2RK2OL6RK2=<g:=< > 698

��� � � ��� � $ N "%$�" �� �>ML6LNRK698

� ��� � � � �� $ � � "%$'" �� �

4X>ZpG8 "%$�" �� � �8-B4J 2;>7q�8�4�B'RK2 q�8�q�rZ6 > 4IB'RK2i: @�<C6)Rf<~< RK6 : �'� ��� � � � � �8�4X>�pG8

� � ��� � � � � � �� � � ��'� � $ D�'� ������� � � � � � � � � ��� ��� $ D

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B §

Page 43: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

0�@fZ 8�TiaMJA\ ^ia L�TXL � c]UtR �UVF a U !^ b E�J T � � � � !

� !L�TXL � c]UtR P E�J L�TXL � c]UtR !L�TXL � c]UtR � c L�TXL � c]UtR !P E�J L�TXL � c]UtRON`U � � � � !c L�TXL � c]UtR � � P E�J L�TXL � c]UtR !c L�TXL � c]UtR � � U � � �"!c L�TXL � c]UtR � � T � � � � ��� � !

0�@fZ 8�TiaMJA\ ^ia GMRih P �Ma�L �\MF T�U��AFSLtH GMRih P]U5alT d � !\MF T�U��AFSLtH b U�� b P]U5alT d � !\MF T�U��AFSLtH d � !

� ! S�S �X� rtBg<e4�B�4�BDq�8�2;@CB >72o8GMRih P �Ma�L � c GMRih P �Ma�L !\MF T�U��AFSLtH T b R�JMa U ! S�S��X� rtBg<e4�BI4IBDq�8�2o@CB >7258c GMRih P �Ma�L � � GMRih P �Ma�L � � � U !U � ��� ��� ��� ! S�S�:o@g@�RKq�> :cb 8 � ? < @CB :�: 4K8 @�< 6 : �c GMRih P �Ma�L � � b U�� b P]U5alT � ��� � ! S�S Uj: >�2=< B 8�258 ��� ����� �c GMRih P �Ma�L � � GMRih P]U5alT � ��� � ! S�S U�: >�2=<`B 8�258 ��� �������

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B �

Page 44: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� 1�x n21�1_nMx)/ -%*M*%! ,%-61w/ 8 RX2i: @�<C6)Rf<~< RK6 : L6R �> :VpG8�698 : >7q�8 q�8�q�rZ6 >RK2^d :NJ�<C6 : @�< 6)R=<><hRK6 :�� L6RK6 :kb �8 4�B < B L�> 4�B pG8�6 @g> � � = ��� � � =�; ; �9� 8 7�; � ; � Z1 UFR58 @�< > LZ6 >MLZ>A@CBg< > >t@g@ 8�6 pXB :Xq > :kb 8 HMJ B�>ML�8�6 :=< > 6 B N 8 � � @g>72o>; � � 8<; � 8 � 8�; 8 � 8 � = ; Z0�@fZ 8�TiaMJA\ ^ia L�Tia�L�JAFSE �

L�TXL � c]UtR � L � P J�R L�TXL � c]UtR !� P E�J L�Tia�L�JAFSE !L�Tia�L�JAFSE � c L�Tia�L�JAFSE !P E�J L�Tia�L�JAFSEON � L � P J�R L�TXL � c]UtRON`U � � � � !c L�Tia�L�JAFSE � � P E�J L�Tia�L�JAFSE !c L�Tia�L�JAFSE � � � L � P J�R L�TXL � c]UtRON`U � � �"!

BsJce :f<~< > 4�Bl2o>�2 L�>c< 8�6 : >�2=< 8�258�6 8 RK2-q 8�q�rZ6 >�4K8cJWJ >�@�< 8 @g@g> < B L�>=2o>�2 �8RK2i:[pG8�6 : J BDq�Bg<g: 5B >72o8 �KB 2=e :=<>< BVRK2i: @�<C6)Rf<~< RK6 :�L6R��>!rt8Z2AB @g@CBDq > : >�2=< 8�258�6 8RK2)q�8�q�rZ6 > L6RK2=<g:=< > 698!:6JK@�Ro>-@�< 8 @g@g> <`B4L�>KZ0�@fZ 8�TiaMJA\ ^ia c J�R P E �

Y�GMRME�a � !c J�R P E � c c J�R P E !

� P E�J c J�R P E �!1 P E�J c J�R P E � !P E�J c J�R P E ��NQc c J�R P E � � P E�J c J�R P E � !P E�J c J�R P E � NQc c J�R P E � � P E�J c J�R P E � !P E�J c J�R P E ��N � � � � � N � �"!

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B �

Page 45: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

P E�J c J�R P E ��NQc c J�R P E � � c c J�R P E � � � � � � � N � �"! S�S��

� *%!`(+* 8 J > : : 5B >72o8 �/B�� 4�B q 8�q > 6 B : : >�254�B pKB @ :)4 : 4FR58�> LtB��R�pZ:Z6 B :KrtB4J BsZ? B�4�B :cb B :Z6 : B 2 q >�4X>�@CB q�B4J 8!:�RX2i: @�< 6)R=<>< RK6 :

\MF]UtRGF ��� � �#� �� � � � & �!� " $ & !� � � � * �!� " $ * !

,,� � ��� � � �'� � $ & ( �� � � ��'� � $ * ( ����� � D

� 8 q >�4 :6J Bg< �: 4�B : :�: 8 @g@g> @g>�2o> J 8 @�</8 @g@ 8 4�B@UMR58cJWJ 8 4K8cJWJ 8 @�< 6)R=<><hRK6 8 �@CB R=<`B4J B V:X2o> HMJ BO>%Lt8�6 :=< >M6 B N 8 � � Z � : 4�B q�8�2o@CB >�258 �8 UFR58cJ`J : 4X8cJ<`B4L�> 4�B 4�BDq�8Z2o@CB >�258�q :=H�H B > 6 8NZO1 4 >�H72ABSB @�<g:K2=< 8�B J : >�2=< 8�26R=< > BD2 RX2i:pZ:Z6 B :KrtB4J 8 RK2AB >72 �8 RK2 4 :=< > � RK2o> @g>MJ >�� � 4�B�RK2o> 4K8iB�<`B4LAB�@�L�8 : B�� : :=<`B258cJ`J :=4�B :cb B :Z6 : 5B >�258 �OB JK< B4LZ> pXB 8�2o8#@ 8cJ 8 5B >�2i:=< > BD2 rG:o@ 8 :6J 2o>�q�8 :kb 8Ro@g> � �!�#"%$ & ()�!� " $ * ( � ��� � Z0�@fZ 8 \MF]UtRGF FM\�� L�J�R �

UVF a U !Y�GMRME�a � !

� P E�J FM\�� L�J�R !P E�J FM\�� L�J�RON`U � �"!P E�J FM\�� L�J�RON � � � � � N � ! S�S P E�J FM\�� L�J�RON`U �8$@g>ZpM6 :o@ : 6 B <~<g: �

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B B

Page 46: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� *%!`(+* -%*^(+*%!$.0/ 8 @ pG>%J Ht>72;> RX2 : >�q LABg< > @CBDq�B4J 8�:YUFR58kJWJ >�4K8cJWJ 8 RK2AB >�2q : 2o>�2 4K8 �]2AB @ : >�2o> RK2 26Ro>ZpG> < B4LZ> 4�B_4 :f< > �e@ 8�6 p5>72;> : 4�BD698 :kb 84FR58 > LAB��R pZ:Z6 B :KrAB4J B �,4�B :cb B :Z6 :f</8 :6J`J4d BD2=< 8�6,2o> 4K8cJ`J : RK2AB >�2 q : pXB @CB rAB4J B4 :6J`J4d 8 @�< 8�6,2o> � : >�254�B pKB 4X>72;> J : @�< 8 @g@ :OJ > : : 5B >�258.4�B]q�8Zq > 6 B :

\MF]UtRGF �� � � � & ��� � � ��'� � $ & !� � � � * ��� � � ��'� � $ * !

,,� D

0�@fZ 8 \MF]UtRGF �UVF a U !Y�GMRME�a � !

� !U � �"!� � � � � N � ! S�S U �8.@g>Zp 6 :o@ : 6 Bg<><g: �

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B #

Page 47: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� #M/�x)-61w(%x)/ ,5!M-2] ] /�oQ*^-%.0/�*21�( �V(+* TiaMJA\ ^ia / \MF]UtRGF�8 :$4�B��?8Z698�2 :4K8_H%J B :Z6,6 :�� : : RtBJ4d >%Lt8�6 :=< >M698 4�B_:o@g@ 8_H�2i:Kq 8�2=< > � 2o>�2 L6R��> 8 @g@ 8�6 8:6L6LNJ B : :=< > � � � �]1 8 B4J�2o>�q�8�4�B RK2 :Z6Q6 :�� �8 RK2 LNRK2=<g:=< >M698 : >A@�<g:K2=< 8�� �8 :cb 8 UFRAB 254�B pZ:K2K2o> :o@g@ 8_H�2i:=<`B[8kJ 8�q�8�2f< > Lt8Z6�8cJ 8�q 8�2=< > �!258kJ : :o@g>4�B pZ:Z6 B :KrAB J B 4IB'<`B4L�> TiaMJA\ ^ia 8 \MF]UtRGF J4d >%Lt8�6 :f< >M698�4�B�:o@g@ 8_H�2i:Kq�8�2f< >8 �?8 <~< Ri:0J4d 8 @ :=<><g: : >MLAB : 4K8kJ q�8Zq�rZ6 >�4�B�4K8 @�< 6 :�BD2 UFR58cJWJ > 4�B�@CB 2AB @�< 6 :�Z

1 � � 0 ��� B � � 0 8 :K2 :kb 83B4J : >�2=</8Z26R=< >�4�BkRK2�q�8�q�rZ6 >�4IB <`B4L�> L6RK2f< :=< > 6 8pXB 8�258 4FRNL6J B : :f< > L�8�6 : RAB�� 4A>MLZ> J : : >%LAB :�� 8�2=< 6 :Kq�r�8 B q�8�q!rZ6 BL6RK2f< :=< > 6 8 LNRK2=<g:K2o> :6JWJ : @�< 8 @g@ :OJ > : : 5B >72o8�4IB]q�8�q�> 6 B : �

0�@fZ 8�TiaMJA\ ^ia L�TXL � c]UtR �UVF a U !UVF a � 3"!Y�GMRME�a � !

� E 1 P !EON 3 � � UVF a � � � E2G2GMR�^ � T�U��ILMRtY � UVF a � � !EON`U � � � !� EON 3 � � � !EON � � � N���� !P � E ! S�S PeN`U p�:NJ 8 � s � � PeN 3 pZ:6J 8 � m 8 PeN � pZ:6J 8 iMZs�_�� PeN 3 � � �"! S�S�:K2 :kb 8 � EON 3 pZ:6J 8 � � ���

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B �

Page 48: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� x xz-�� -%3{3��s!s*21w/\x *^( ,5!OnM*^- ]�1_x~n21w1�nMx)- 8 @ 8 RK2i: @�< 6)R=<><hRX6 : b : RK2q�8�q!rZ6 >=4IBM<`B4LZ> :Z6,6 :�� ��J : q�8�q >M6 B : 698cJ :=< B p�:�:NJWJ4d :Z6,6 :�� pXB 8�258 :NJWJ > : :=<g::6JWJ d BD2=< 8�6,2o> 4K8kJWJ :=@�<C6zR=<~< RK6 : 8 J4d >%Lt8�6 :f< >M698�4�B�:o@g@ 8_H�2i:Kq�8�2f< > 8 �?8�<><hRG:RK2i: : >MLAB : 4K8cJWJ d BD2=< 8�6 > : >72f</8�2NR=< > 4K8cJ`J : @�<C6zR=<~< RK6 :)8 UFRABD2o4�B :K2 :cb 8�4�B< R=<~<`B^HMJ B�8cJ 8Zq�8�2=<`B 4K8cJWJ4d :Z6Q6 :��=Z

TiaMJA\ ^ia � UXTM^ �UVF a U ��� � !

� !

� UXTM^ E � � �!1 � 1 � 1 �)1 �41 � ! �� UXTM^ P ! fMf T�U��ILMRtY � � UXTM^ � P E2GML � �P � E ! fMf EON`U � � � P E2GML �!1 PeN`U � � � P E2GML �PeN`U � � � � � � ! fMf EON`U � � � P E2GML �!1 PeN`U � � � P E2GML � �

� �W���C� ¢{�I� �{� ����%� �¦��¥��¦ B �

Page 49: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� � ���9�E����� �c����� �k� ����� �� � ������� ����� � �

� nM*^qc!W(+*%! 8 @g>�2o> B q >�4FR6J B BD2o4�B4Lt8Z254K8�2=<`B :cb 8 : >t@�< Bg< RAB @ : >72o> RK2LZ6 >�H76 :Kq�q : A�S�A����jZ � 8=4K8 pG8 8�@CB @�</8Z698 :6J q�8�2o> RK2o> 8 J : e~RK2 5B >�258� EIUVF ����Z � 8 e~RX2 GB >72AB�@g>72;> : >A@�<`Bg< RABg< 8�4 : B @�< 6)R 5B >72tB :cb 8 J :Vp5> 6 :K2o> @�R4 :=<`B BD2 B 2XH76 8 @g@g> @g>c<~< > e >M6,q : 4�B ;+=�� �� ����� 8 > � ;+=�8<; � 8 � 8 � � ��; � 8 L�8�6LZ6 >�4FRK6Q698 4K8iB 6 B @�RNJ�< :f< B?BD2 Ro@ : B < :�@g>c<~< >0e > 6,q�:#4�B ;+=�� �� ����� 8 � � ;+=�8<; �98 � 8� � � ; � 8 > � ; � =�8 7 8 =�8 � = ���Z � 2i: e~RK2 5B >�258 b :�J : e >M6,q :

� �����%�!�#"%$ � � � ����� & ��� � � �'� � $ & ( � ����� * ��� � � �'� � $ * ( ����� � �����'� ���������#�!$ & �

���'� ���������#�!$ * �

,,� J�L�aA\ JAF � $ � � � $ � � � �#�!$ � � �

4X>ZpG8 �!� " $ �8 B JS2;>7q�8.4K8kJWJ :�e~RK2 5B >�258 � � ����� �8 B4J�<`B4L�>�4X8cJWJ4d 8 @�LZ6 8 @g@CB >�258$ � � � $ � � � � � $ B4J : RABMpZ:6J > 698 LZ698�254X8�B4JS2o>�q�8�4�B�� ; �< = � 7 8 =�8 � = � �� ������� &��� � � �'� � $ & ( ������� * ��� � � ��'� � $ * ( ����� @g>�2o> 4IB :cb B :Z6 : GB >72AB 4�B3pZ:Z6 B :KrtB4J B4K8�<>< 8 � ;+= ; � �+� =�8 � = � ; � 8 > ;+=�� �� ��� � 8 :cb 8 pi8Z2XHA>�2o>OR;@ :=</8�:6J`J4d BD2=< 8�6,2o>4K8cJ`J : e~RK2GB >�258 : >7q 8 RK2G: UFRi:6J @CB :o@CB+:6J <C6 : pZ:Z6 B :KrAB J 8NZ � 8 B @�< 6)R 5B >�2AB

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� B �

Page 50: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

6 : :_:cb B4Ro@ 8 e 6 : J 8 Li:Z698Z2=</8�@CB�H�6 : �]8 � � LZ698�2o4X>72;> B4Je2o>7q 8 4�B �� = � 7 ��� � ; �/��� >#8 �9�XZ

� ���]1 8 J :�pi8 :�:cb B :�@CBD2=<g:o@g@CBFA

� �����%�!�#"%$ � � ��� � � ��� � $ & ( ��� � � ��'� � $*+( ����� � �� � � � � & ��� � � ��'� � $ &�� �

� � � � � * ��� � � ��'� � $ * � �

� ���

�,,�

2o>�2��8�pZ:6J B 4 :)BD2 A � �jZ0�@fZ 8$UVF a TXR ��� E � UVF a E 1 UVF a P �

�UVF a T !T � E � P !J�L�aA\ JAF T !

78Z6�8 @ 8_H%RABD6 8 RK2i: e~RK2 5B >�258 �8 258 : 8 @g@ :Z6 B : J4d B @�<C6)RGB >�258 4IB ��: 8 ; � ; � ;; �.��� >#8 9� � BD2 RK2^d :6J�< 6 : e~RK2GB >�258 �)UFRi:K254A> b : BD2AB 5B > J4d 8�@ 8 : R 5B >�258

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� B

Page 51: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

4K8cJ LZ6 >�H�6 :Kq!q : pXB 8Z258 :cb B :Kq :=<g: :6Rf< >�q :=<`B : :Kq 8�2=< 8 J : e~RK2 5B >�258� EIUVF ��� � Z � d 8 @ 8 : R GB >7258 4K8cJWJ : e~RX2 GB >7258 < 8�6,q�B 2i: 2o>�2 :6L6Lt8Z2i:pXB 8�258 BD2 : >�2=< 6 :=<g: J4d B @�<C6)RGB >�258 J�L�aA\ JAF � $ � � � $ � � � � � $ � D � � � �]1 8 L6R��>8 @g@ 8�6 : 8�258 LAB��R 45dsRK2i: � > �?@ 8�UFR58 @�<g: 2;>72 : d �8 � J4dsRNJ�< B q : B @�< 6)R 5B >�258#4X8cJ: >M6)L�>�4X8cJWJ : e~RK2 5B >�258NZ � : @CB 2=< :;@g@CB 4K8kJWJ : :cb B :Kq�:=< :�8

� �� � � ��'� � $ � � �!� " $ � � ��� � � ��� � $ & ( ��� � � ��'� � $ * ( ��� � � � !

4X>ZpG8 �� � � ��'� � $ &�( �� � � ��'� � $*+( � ��� @g>72o> pZ:Z6 B :KrtB4J B > : >t@�<g:K2=<`B� ;+=�� �� � � � 8-7 � � � ; ��: 8<; � ; � ; ��4�B :kb B :Z6 :=< 8 258cJWJ : e~RK2GB >�258 :cb B :Xq :K2=< 88 4K8CpG>�2o> 8 @g@ 8�698 J > @�< 8 @g@g> 26RKq�8�6 > 8 4K8kJWJ > @�< 8 @g@g> < B L�> 4X8iB: >M6,6 B @�LZ>7254X8�2=<`B � ;+= ; � ��� =�8 � = � ; � 8 258cJWJ : 4K8 �?2AB�GB >�258 4K8cJ`J : e~RK2 5B >�258�!�#"%$ � 2o>�2 �8 258 : 8�@g@ :Z6 B > :kb 8 :KrKrAB :K2o> J > @�</8 @g@g> 2o>�q�8�� Z � RK6 :K2=< 8J : :cb B :Xq :=<g:�� >�H�26RK2o> 4K8GB � ;+=�; � �+� =�8 � = � ; � 8 pXB 8�258 BD2AB 5B :6J B :=< >: >�2 J4d ;+=�� �� � � �� 7 ��� � ; � : 8<; � ; � ; 258cJ`J : L�>t@CB GB >7258 : >M6,6 B @�LZ>7254X8�2=< 8NZ��� � � �'� � $ �8�:X2 :cb d 8 @g@ :)4�B :cb B :Z6 :=<g: 258cJWJ :0e~RK2 5B >�258 :cb B :Kq :K2=< 8#8#4K8 pG88 @g@ 8�6 8 4X8cJWJ > @�< 8 @g@g> <`B4L�> 4K8cJ � ; � = � 7 8 =�8 � = �� 4K8cJWJ : e~RX2 GB >7258 � BD2UFRi:X2=< >�UFRo8 @�<�dsRNJ�< B q >�J 8_pXB 8Z258 :o@g@ 8�H72i:f< >"UFRG:K254X> J :@e~RK2 5B >�258�< 8�6,q�B 2i:J4d 8 @ 8 : R 5B >72o8 : >�20J4d B @�< 6)R 5B >�258 J�L�aA\ JAF $ � � � $ � � � �#�!$ DIZ

� ���]1 8 RK2i: e~RK2 5B >�258 :cb 8 2o>�2 6 Bg< >M6,2i: pZ:6J > 6 B b : P RIUGH : >7q�8 <`B4L�>:o@g@g> : B :f< >�8 < 8�6,q�BD2G: : >�2 J4d B @�< 6)R 5B >�258 J�L�aA\ JAF ! > �A@ 8 UFRo8 @�< :!2o>72 : d �8 �: >�20J4dsR6J�<`BDq : B @�<C6zR GB >7258 :cb 8 :cb B R54K8 B4J : > 6)LZ>�4K8cJWJ : e~RX2 GB >7258�Z

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 52: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

0�@fZ 8$UVF a U � � � 1 3 � � !Y�GMRME�a � � � N���� !3 � Y � U21 ��� � !N fMf 4X>MLZ> J : :cb B :Kq�:=< : U p�:NJ 8 � s � � p�:NJ 8 s Zs�_��8 3 pZ:6J 8 � stsNUVF a Y � UVF a U21 Y�GMRME�a � c � ��

U � � U !� c � � � c � � � !J�L�aA\ JAF U !

0�@fZ 8$UVF a U � � � 1 3 � � ��� !UVF a � c UVF a !Y � � U21 � c UVF a � !3 � � c UVF a ! fMf 3 P E2GML � �NNP RIUGH Y � UVF a � U21 UVF a ��� c UVF a � �� c UVF a � U !

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� #�§

Page 53: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� x)(�1w(�1�!$#%!a,5!�& nM*^qc!W(+*^/ 8 BD2 A ��� <hRf<~< 8 J 80e>RK2 5B >72tB�4K8 p5>�2o> 8 @g@ 8�6 84�B :kb B :Z6 :=< 8 � =�8 � ; 4K8cJ�J >M6 > Ro@g> ��8 UFR58 @�< > pXB 8Z258 e :=<>< > :=<><C6 :VpG8�6 @g> RK2� = ����� 8 � 798 �.� � >?8 � �=Z � :�@CBD2=<g:o@g@CB�4�BQRX2 � = �� � 8 � �8

� � � �%�!� " $ � � � � � �+& � ��� � � ��'� � $ & � ( ������� * � ��� � � ��� � $* � ( ����� � �^D

B|LZ6 >�< >�<`B4LAB : >�2o@ 8�2f< >�2o>):6J : >�q LAB4J :=< >M698.4�B

7 HA8 @�<`BD698 : >M6,698�<>< :Xq�8�2=< 8 B4JAp�:NJ > 698�4�B 6 Bg< > 6,2;> 4 :�RX2i: :kb B :Kq :f< :^D7 B 254�B pXB 4FRG:Z698 8 @ 8_H72G:6J :Z698 4�B��?8�6 8�2 �8 8 BD2 : >�q Li:=<`BDrAB J Bg< �: e 6 : B4J2NRKq�8�6 >=8�B4J\< B L�> 4K8�HMJ B :Z6¤Ht>�q�8�2=<`B74K8cJWJ : :kb B :Kq :f< :#8�B�Li:Z6 :Xq�8�< 6 Be > 6,q :NJ BsZ

m6- & nM*^qc!W(5*^/ � EIUVF ��� 8 �8OJ :je~RK2GB >�258 4 : : RAB?BD2AB 5B : J4d 8 @ 8 : R GB >7258 4X8cJLZ6 >�H76 :Kq�q :=8�4K8Cpi8-@ 8Zq LZ698-8 @g@ 8Z698 LZ698 @ 8�2f</8NZ ?I8 2o>�2 �8-@�Lt8 : B � : :f< >B4J\<`B4L�> :;@g@g> : B :=< > �8 4�B%<`B4L�> UVF a 8 4 �8ORo@�RG:6J 8 </8Z6,q�BD2i:Z6 8 � EIUVF ��� : >�2J�L�aA\ JAF s D � @ 8 J4d 8 @ 8 : RGB >�258 �8 < 8�6,q�BD2i:=<g: : >M6,698�<>< :Xq�8�2=< 8 �/BD2 UFRo8 @�< >q >�4X> :cb B b : J :K2 : B :=< > J4d 8 @ 8 : R 5B >72o8 b :�q >�4X>�4�BG@ :NLt8�698 :cb 8 �8�:X254 :=<g::�r6Ro>�2 �]258 �^<C6 :Kq�Bg< 8 B4J�pZ:6J >M698$4�B 6 Bg< > 6,2;>-4�B � EIUVF ��� � Z � EIUVF ��� b : J :Li:Z6I<`B : >%J :Z6 B < �:�4�B�LZ>�< 8�6]:VpG8�6 8$BD2!BD26L6Rf<_4K8iB5pZ:6J >M6 Bi@�Lt8 : B�� : :=<`Bi@�R6JWJ :�J BD2o8;:4K8cJ : >�q :K254A> 4�BI8 @ 8 : R 5B >72o8�4K8kJ5LZ6 >�H�6 :Kq�q :^Z�?I8-2;>72�@�Lt8 : B�� :kb B :Kq >:6J : RK2 Li:Z6 :Kq�8�< 6 > e >M6,q :6J 8�Lt8Z6 � EIUVF ����UFR58 @�<`B p�:NJ > 6 B�@ :Z6 :K2K2o>.BgH72o>M6 :=<`B��@ 8 BD2VpG8 : 8�p5>�H%J B :Xq > R=<`B4J B V:Z6zJ B�4X>�rKrAB :Xq > Ro@ :Z698 J : e > 6Qq :

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 54: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� � ����� � � EIUVF � UVF a E�J �l^ 1 ^ b E�J � E�J � P ��� �

������ S�S : >M6)L�> 4�B � EIUVF ����

�O>%L�> J : :cb B :Kq :=<g: E�J �l^ : >72f</8�6Q6 �: B4J 26RXq�8�6 > 4X8_HMJ B :Z6¤Ht>7q 8�2=<`B@�R6JWJ : J BD258;: 4�B : >7q :X254X> :6RKq�8�2f< :=< > 4IB�� � J4d :Z6,6 :�� E�J � P : >72=< 8�6,6 �:4K8iB L6RK2=<g:=< > 6 B�: UFR58 @�<`B Li:Z6 :Kq�8�< 6 B�BD2 e >M6,q :=< > @�< 6 BD2XHK:��-: LG:Z6I< B 6984 : E�J � P � � �+D E�J � P � � � �8 @ 8�q LZ698 RK2 L6RK2=<g:=< > 698 :6J 2o>�q�8 4X8cJLZ6 >�H76 :Kq�q :�Z ?I8 J4d 8 @ 8_H%RABDrAB J 8 : > 6,6 B @�L�>�254K8�2f</8 :6J�LZ6 >�H�6 :Kq�q : 2o8cJ@ 8_H%R58�2=< 8 8 @ 8�q LAB > @CB :cb B :Xq : a�L�Tia 8 pKB 8�258 J :K2 : B :f< > : >�2 B4J : >7q�:K254X>� a�L�Tia � � c J�R P E d0�@fZ 8 � EIUVF � UVF a E�J �l^ 1 ^ b E�J ��� E�J � P �

������ S�S : >M6)L�>�4IB � EIUVF ����

E�J �l^ pG8�6,6 �:�BD2AB�GB :NJ B V:=< >-:�i�� E�J � P � � � : �c< 8 @�< � � E�J � P � � � : �F� s � 8E�J � P � � � : �MLZ6 >ZpZ: �KZ

� -2x~!`-%t%!s34!KoQ3`(5t^-%3{!5/ y2!`]_!st%!$3{!}1��- 8 >%J�<C6 8.:6JWJ 8�p�:Z6 B :KrAB4J B � � ; � 8 B4J : RABK@ : >%L�>�8 J BDq�B < :=< > :6J � � ���' � � BD2 : RAB @g>72;> 4K8 �]2ABg< 8 � �8 L�>t@g@CBDrAB4J 8 4K8 �?2AB 6984K8cJ`J 8�pZ:Z6 B :KrAB J B � ��� = � � : UFRG:6J @CB :o@CB%e~RX2 GB >7258�Z � :6J B pZ:Z6 B :XrAB4J B7@CB74�B : >72o>� � � ; � 8 8 4 8 @CB @�< >�2o> Lt8�6 <hRf<~<g: J : 4FRK6 :=< : 4K8cJWJ d 8 @ 8 : R 5B >�258�D J : J > 6 >

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 55: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

pXB @CBDrAB J Bg< �:�L6R �> :K254M:Z698�4 :6J @ � �3BD2 : RABZ@g>72;>�4K8 �]2ABg< 8 � pXB @CBDrAB4J Bg< �: q�BD2tBDq : ��]2o> :6JWJ4d BD2f</8�6 > � = � = ; � � ; Z � 8 pZ:Z6 B :KrtB4J B H%J >7rG:6J B3@g>�2o> pXB @CBDrAB4J B 4 :UFRi:NJWRK2TUFRo8 e~RK2 5B >�258 8 rtB @g>�H�2i: L�8�6 �> 6 B : > 694 :Z6 8 :cb 8 � BD2 LZ698 @ 8Z2 V: 4�BRK2i:�pZ:Z6 B :KrtB4J 8jH%J >�ri:6J 8 8 RK2i: J > : :6J 8 : >72 J > @�< 8 @g@g> 2o>�q�8 � B4J�2o>�q�8 @CB6 Bge 8�6 B @ : 8�@ 8�q LZ6 8 :6J`J :�pZ:Z6 B :KrAB4J 8 � � ; � �=Z 6 R58 @�< >�8 pG8�6 >�BD2lHX8Z258�6 :6J 8 8 BD2LZ698 @ 8Z2 V:#4IBS4MR58�pZ:Z6 B :KrAB J B : >72 J > @�</8�@g@g> 2o>�q�8 4�B :kb B :Z6 :=< 8�BD2 r6J > :�:kb B4�B pG8�6 @CB�� B4J 2o>�q�8 @CB 6 B e 8�6 B @ : 8-:6J`J :#pZ:Z6 B :KrAB4J 8 4�B :kb B :Z6 :=<g: 258cJ r6J > :�: > LAB��R8 � � � = �� � �]2 :cb��8 �8 BD2�@ : >%L�> ��Z

� #%/ ��!����V-61�(%x>! ,5! �N3}-2] ]_! ,5! .0/�.0(%x~!`- 8 @ 8�6 p5>�2o> : B @�< 6)RAB 698 B4J: >�q LAB4J :=< >M698.@�R6JWJ 8#q >�4 :6J B < �: 4�B q 8�q > 6 B : 5B >�258!4�BQRK2i:�pZ:Z6 B :KrAB J 8NZa? BRo@ :K2;> 258cJWJ 8�4�B :kb B :Z6 : 5B >�2AB9LZ6 BDq : 4K8cJN< B4LZ>5Z�? >72;> 8

7 EG\ a�RF8 :6J`J4d BD2=< 8�6,2o>)4�BQRK2=rNJ > :�: > 4�B :kb B :Z6 :�RK2i:�pZ:Z6 B :KrAB4J 8 � � ; � �=D]BD26 8;:6J�< �:�2o>72�@ 8�6 pG8jLt8Z6 :cb��8 �8$@g>�<><�d B 2=</8�@g>5Z

7 L � a�L�JAF�8 @ 8 Ro@ :=< > e~Ro> 6 B 4 : RK2 r6J > :_: > 4�B :cb B :Z6 : :kb 8 J :-pZ:Z6 B :KrtB4J 8� � ��; � � �8 H B �: @�<g:=< : 4K8 �]2ABg<g: BD2 RK2#:6J�< 6 > �9J 8 �gB J : >7q LAB4J :=< > 6 8�2o>�2:NJWJ > : :�q�8�q�> 6 B : ��8.4FRK2XUFR58jLt8�6Qq�8�<></8 4IB�8�@�</8�2o4K8�6,258�J :�pXB @CB rAB4J Bg< �:�Z�O8�2=< 6 > RK2-r6J > :�: >�4IB :cb B :Z6 : :cb 8 J :.p�:Z6 B :KrAB4J 8 �8 � � � ; � � 8 BD2�UFRo8 @�< >: :o@g> J : 4�B :cb B :Z6 :GB >�258�8-6 B 4X>�254 :K2f</80L�8�6 :cb��8#B4J : >7q LtB4J :=< > 698 : 8�6 : :: >7q RX2TUFR58 e 6 : J 8 pZ:Z6 B :KrAB4J 8 H%J >�ri:6J BaUFR58cJWJ 8 2o>72 4�B :cb B :Z6 :=< 8 � q :Rf< B4J B :=< 8���BD2ORK2)r6J > :�: >KZ

7 Tia�E�a UX^%8 RK2i:�pZ:Z6 B :KrAB J 8 � � ; � � Tia�E�a UX^ �8�Lt8�6Qq :K258�2f</8�:6J`J4d BD2=< 8�6,2o>4IB6RK2�r6J > :�: >$8 : B > �8�B4J @�Ro>�pZ:6J >M698�pKB 8�258 : >�2o@ 8�6 pZ:=< >�:K2 :kb 8 UMRi:K254X>J d 8 @ 8 : R 5B >�258 8 @ : 8 4 :NJ r6J > :_: >KD�RK2i: p5>MJ�<g: :cb 8�J4d 8 @ 8 : R 5B >72o8 < > 6Q2i:

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� #�B

Page 56: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

:NJWJ4d BD2=< 8�6,2;>!4K8kJMr6J > :�: >�B4J;pZ:6J >M698 4K8cJ`J :�pZ:Z6 B :KrAB J 8 �8 UFR58cJ`J > :cb 8�:VpG8 pZ::NJWJ : LZ698 : 8 4K8�2=< 8�Ro@ : Bg<g:�ZaB 2;>MJ�< 698 J4d BD2tB GB :6J B V:GB >�258 pKB 8�258+8 �?8�<>< Ri:=<g:RX2i:#p5>%J�<g:�@g>%J :=:NJWJ4d BD2AB�GB > 4K8cJ`J4d 8 @ 8 : RGB >�258NZ�� 2i:#pZ:Z6 B :KrAB4J 8 � �< ��; � �Tia�E�a UX^ b : pXB @CB rAB4J Bg< �:lJ BDq�B < :=<g: :6J�@g>%J > �'J 8 BD2 : RAB �8[4K8 �]2ABg<g: 8@UFRAB 254�B2;>72 �8jL�>t@g@CBDrAB4J 8 Ro@ :Z6 8 J >-@�Lt8 : B�� : :=< >M698 L � a�L�JAF L�8�6 : :�: 8 4X8�6 pXB 4 :RX2�:6J <C6 > �'J 8�Z

7 J�L � UXTia�L�J98 4�B : 8 :6J : >�q LAB4J :=< >M698 :kb 8 J4d : :�: 8 @g@g> :6J`J : pZ:Z6 B :KrtB4J 84X8 pG8�:Vp;pG8�2ABD6 8 B4J LAB��R�pG8cJ > : 8�q�8Z2=</8 L�>t@g@CBDrAB J 8�D @�<g:=:6J : >7q LAB4J :=< > 6 8q 8�q > 6 B :Z698 J : pZ:Z6 B :XrAB4J 8 BD2 q :X2AB 8�6 : >%L6L�>M6I< RK2i: � L�Z 8NZ BD2 RK26 8_HIB @�<C6 >-4K8cJWJ : A � > 258kJWJ :)q�8�q >M6 B : : : :cb 8 ��Z

� x xz-�� �V(+.0/�#^-2x)-%.0/�1_x~!�&)(%x~.0-%3{! 8 RK2 :Z6,6 :�� �8"RK2lLNRK2=<g:=< >M698 : >t@�<g:K2=< 88 UFRAB 254�B��OUFRG:K254X> : >7q LG:Z698 : >�q�8 :Z6¤Ht>7q 8�2=< > 4K8kJWJ : :cb B :Kq :=<g: :RK2i: e~RK2 5B >�258 � B4J : >M6,6 B @�LZ>7254X8�2=< 8 Li:Z6 :Kq�8�< 6 > e >M6,q :6J 8 2o>�2 L6R �> :kb 88 @g@ 8�6 8 RK2 LNRK2=<g:=< >M698#4X8cJWJ > @�</8�@g@g> <`B4LZ>5Z �0 L�8�6Ie 8�<><g:Kq�8�2=< 8 J 8_H Bg<~<`BDq >4�B :kb B :Z6 :Z698)B4J|Li:Z6 :Kq 8�<C6 > e > 6Qq :6J 8 : >�q�8ORK2):Z6,6 :���4K8cJWJ > @�< 8 @g@g> <`B4LZ> 84�BDq 8�2o@CB >�258 �,8 R;@ :Z6)J > : >�q�8�<g:6J 8�� � @ :Z6 �: B4J : >�q LAB4J :f< >M698-: @g>A@�<`Bg< RABD6)J >:6R=< >�q :=<`B : :Kq�8Z2=</8 : >72 RX2 L6RK2=<g:=< > 698 4IB�UMR58cJ�<`B4L�>KZ 78Z6 J : @�</8�@g@ :6 :XH B >�258 �8 L�>t@g@CBDrAB J 8 4�B :cb B :Z6 :Z6zJ > : >7q 8 RK2 :Z6,6 :�� @ 8Z2 V: 4�BDq�8Z2o@CB >�258NZ?I8 J d :Z6,6 :�� b :�LAB��R�4�B9RK2i: 4IBDq�8�2o@CB >7258 �8-258 : 8 @g@ :Z6 B > :cb 8#B4JQLG:Z6 :Kq�8�< 6 >e >M6,q :6J 8.@CB : 4�B :cb B :Z6 :=< > :6JWJ > @�< 8 @g@g> q >�4X> �Q@CB+L6R��>�>�q�8�<></8Z698jJ : LZ6 B q :4�BDq 8�2o@CB >�258���@ 8 p5>�HMJ B :Kq > L�>c< 8�6[: :_: 8 4K8�6 8�:ABS@�Ro>IB 8cJ 8�q�8Z2=< BF<C6 :Kq�Bg< 8H%J B�>%L6LZ> 6I< RK2ABSBD254�B : BsZ

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # #

Page 57: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� -^xz-%.0/�1�x~! &z(%x .0-%34! / ^XRGF Tia98 L�8�6 8 pXBg<g:Z698 :cb 8 RK2i: pZ:Z6 B :KrtB4J 8pG8�2XHK: q�> 4IB�� : :=< : :6J`J4d BD2=< 8�6,2o> 4IBRK2i: e~RK2GB >�258 �8 LZ>A@g@CB rAB4J 8 Ro@ :Z698 B4Jq >�4�B�� : :=< > 6 8 ^XRGF Tia 258cJWJ : 4�B :kb B :Z6 : 5B >�258!4X8iBQLG:Z6 :Kq�8�< 6 B2e > 6Qq :6J BsZ0�@fZ 8 P RIUGH Y � ^XRGF Tia UVF a � � !

P RIUGH � EIUVF ��� �UVF a U � � � !UVF a � c UVF a !c UVF a � � U !Y � c UVF a � !

�P RIUGH Y � ^XRGF Tia UVF a � c UVF a � �

UVF a 3"!3 � � c UVF a !�fMf 3 pZ:6J 8 � s� c UVF a � � ��� ! fMf 8�6,6 > 698��

� nM*21�-61w(%x~!�- & nM*^q�!`(+*%! 8 L�> B :cb �8 : RK2G: e~RK2 5B >�258 �8 :o@g@g> : B :=< > RK2BD254IBD6 B �> 4�B q 8�q > 6 B : �8 L�>t@g@CBDrAB4J 8 :VpG8�698 RK2 L6RX2=< :f< >M698 : e~RK2 5B >�258�D:�UMR58 @�< > LZ6 >MLZ>A@CB < >�> :�: >M6,698�6 B : > 694 :Z6 8 :cb 8!:6J 2o>7q 8�4�BQRK2i: e~RK2 5B >�258�Q@ 8�2 : Li:Z6 8�2=< 8 @CB ��� ���8 :o@g@g> : B :=< > J4d BD2o4�BD6 B > 4K8cJ � ������ 7 8 ��� � = ; � ; Z� 2 LNRK2=<g:=< >M698 : RK2i: e~RK2GB >�258 4IB�< B L�> � ����� : >72 LG:Z6 :Kq�8�< 6 B�e > 6,q :NJ B� � ������� & ��� � � ��'� � $ & ( � ����� * ��� � � �'� � $ * ( ����� � �.@CBt4�B :cb B :Z6 : 258cJi@ 8_HMRo8�2=< 8q >�4X> 8

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 58: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� � � � � � � ��� � � � �� $ � � � � � � � &�� �!� " $ &�� ( � ����� * � �!�#"%$ * � ( ����� � � !

4X>ZpG8 �!� " $ & ( �!� " $* ( ����� @g>�2o> 4X8iB 2o>7q�B >%L 5B >�2i:6J B :cb 8 2o>�24�B :kb B :Z6 :K2;> pZ:Z6 B :KrtB4J BsZ � @ :K254X> B4J L6RX2=< :f< >M698 � � � � ��� ��� $ :6L6Lt8Z2i:4K8 �]2ABg< > J : :cb B :Xq :=<g: : e~RK2GB >�258 �8�B 2VpG8 : 8

� ��� � � ��'� � $ � �� � � ��� � � � �� $ � � � ��� � � �'� � $ &'( ��� � � ��� � $*�( ����� � � !

� :�: >M6,698YLZ698 @�<g:Z698�:=<></8Z2 GB >7258�: : >�q�8 @CB%Ro@ : a��AcSLtHILtY 258kJ : :;@g> 4�B�RK2L6RK2f< :=< > 6 8!: e~RK2GB >�258 8 J4d B @�< 6)R 5B >72o8�@ 8_H%R58�2f</8

a��AcSLtHILtY � ����� � � �!�#"%$ � � � � ����� & � �!�#"%$ & � ( ������� * � �!�#"%$ * � ( ����� � � !

4�B :kb B :Z6 : �!�#"%$ : >7q�8 @CBD2o>�2ABDq >$4X8cJ < B L�>�LNRK2=<g:=< >M698e: e~RK2GB >�258+4�B_<`B4L�>� � � � : >72 Li:Z6 :Kq�8�< 6 B6e > 6Qq :6J B 4�B2< B L�> ������� &'( � � � ��*+( � ��� Z B 2�]258 � B4J � ; �: L6RK2=<g:=< > 698�: e~RK2 5B >�258 4�B%< B4LZ> � ����� : >�2 Li:Z6 :Kq 8�<C6 BFe >M6,q :6J BS4IBF<`B4L�>� � � � & ( ������� * ( � ��� @CB�@ : 6 B pG8

� ������� � � � � � ������� & � �!�#"%$ &�� ( ������� * � � � " $ * � ( ����� � � � � � � � ��� ��� $ �

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 59: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

0�@ 8�q LAB > 8 UFRi:NJ4d �8 J d >MR=< L6R=< 4X8cJWJ4d 8 @ 8�HMRAB rAB4J 8 � </8 @�< d � 6 8cJ :=<`B p5>#:6JZ@g>M6¤HA8�2=< 8@ 8_H%R58�2=< 8��"J :K2 : B :=< > : >72 :Z6¤Ht>7q 8�2=<`B �$RX2o> 4FR58�d �

P RIUGH Y � UVF a)1 ^XRGF Tia ^ b E�J � ^XRGF Tia � � !a��AcSLtHILtY P RIUGH � � ��� Y � � UVF a)1 ^XRGF Tia ^ b E�J � ^XRGF Tia � � !Tia�E�a UX^ UVF a 5 � � !

� EIUVF � UVF a E�J �l^ 1 ^ b E�J ��� E�J � P � �P RIUGH � � c � Y � � � UVF a)1 ^XRGF Tia ^ b E�J � ^XRGF Tia � � !��� Y c � Y � !c � Y � � Y !c � Y � � � P RIUGH � � � � UVF a)1 ^XRGF Tia ^ b E�J � ^XRGF Tia � � � c � Y � !� � c � Y � � � E�J �l^ 1 E�J � P � !5 � � !� � c � Y � � � E�J �l^ 1 E�J � P � !J�L�aA\ JAF � !

P RIUGH Y � UVF a U21 ^XRGF Tia ^ b E�J � ^XRGF Tia � c � ^ b E�J � �J�L � UXTia�L�J UVF a 3"!YIR�J � 3 � U � � ! 3 � � 5 ! 3 ��� �^XRG\ a ��� c � ^ b E�J � 3 � ��� � � !

^XRG\ a ��� � � F � !J�L�aA\ JAF !

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� # �

Page 60: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ���]1 8 ^XRGF Tia ^ b E�J � �8 RK2 L6RK2f< :=< > 6 8 : : >t@�< :X2=</8 ^ b E�J � ^XRGF Tia^ b E�J � ^XRGF Tia �8 RK2 L6RK2=<g:=< > 698 : >t@�<g:K2=< 8 : : >t@�< :K2f</8 ^ b E�J 8 BD2�]258^XRGF Tia ^ b E�J � ^XRGF Tia � �8 RK2 L6RK2f< :=< > 6 8 : L6RK2f< :=< > 6 8 : >A@�<g:K2=< 8 :: >t@�< :X2=</8 ^ b E�J Z� ! �V(%xz]_!W(5*^/ 8 H�6 : 5B 8 :6JWJ 8 6 8_HA>%J 8 4�B+@ : >%L�> 4K8cJWJ 8 pZ:Z6 B :KrtB4J B J > : :6J B�� �8J 8_H Bg<>< B q > :cb 8 RK2i: e~RK2 5B >�258 8 �?8�<>< RAB�RK2i: :cb B :Kq :=<g: : @ 8 @�</8�@g@ :���: 8<; � ; � ; = 8 �� = 8 � ; � Z ��B : >M694�B :Kq�> BD2=e :f<~<`B :cb 8 J 8 pZ:Z6 B :KrAB J B J > : :NJ B:6JWJ d BD2=< 8�6,2o>�4IBQRK2)r6J > :�: >#@g>�2o> Lt8Z6Ie 8�<>< :Xq�8�2=< 8$4�B @�<`BD2=< 8.4 :6JWJ 8 pZ:Z6 B :KrtB4J B: >�2 J > @�< 8 @g@g> 2o>�q�8 8 @�< 8�6,258):6J r6J > :_: > 8 RK2i: :cb B :Kq :=<g: 6 B : >M6 @CB pZ:�e :LZ6 >t@ 8_H%RABD698 J4d 8 @ 8 : R GB >7258 BD2 RX2 26Ro>Zp5> r6J > :�: > RXH%Ri:6J 8 :6J LZ698 : 8 4X8�2=< 8�/B4J : > 6)LZ> 4X8cJWJ : e~RK2 5B >�258 : >�2o@CB 4X8�6 :=<g: � 8 :kb 8 @�<g:=:NJl@�Ro> BD2=< 8�6,2;>5Z0B 2:6J�< 6 B < 8�6,q�B 2AB_: >�H72tB :cb B :Kq�:=< : 6 B : >M6 @CB pZ: pXB 8�258 :NJWJ > : :=<g: RK2i: : >MLtB :��LZ6 B pZ:=<g: � 4K8cJWJ 8 pZ:Z6 B :KrAB J B J > : :6J B 4K8cJ`J : e~RX2 GB >7258�Z �e@g@ 8�6 pXB :Xq > : >7q 8J4dsR=<`B4J B� > 4K8cJ`J > @�<g: :�� @CB : Lt8�6Ie 8�<~<g:Kq�8Z2=</8 :54 :=<>< > :6J`J : 6 B : > 6 @CB >�258NZ 1>�H72AB :cb B :Kq�:=< :��#B 2=e :=<>< B � J : q�8�q >M6 B : L�8�6 J 8 p�:Z6 B :KrAB4J BYJ > : :6J BepXB 8Z258:6JWJ > : :=< :�@�R6JWJ >)@�<g: :�� ���8�: :�: 8 @g@CBDrtB4J 8!4MRK6 :K2=< 8 J4d 8 @ 8 : RGB >�258�4K8cJ r6J > :�: > �8 pXB 8�258 4K8V:6JWJ > : :=<g: 4 :6J`J > @�<g: :�� �/BD2 > 694�B 258 BD2VpG8�6 @g> : UMR58cJWJ > 4�B:6JWJ > : : GB >7258 � UFRi:X254X> J : :kb B :Kq :f< : < 8�6,q�BD2G: 8 : UFR58 @�< > L6RX2=< > J :@CBg< Ri: 5B >�258�@�R6JWJ > @�<g: :�� �8�8 @ :f<~<g:Kq�8�2f</8 UFR58cJWJ : :cb 8[@CBo:VpG8 pZ: LZ6 BDq :34K8cJ`J ::cb B :Kq :=<g: 8 J4d 8 @ 8 : R GB >7258 L6R��>jLZ6 >t@ 8_H%RABD698 : > 6Q698�<>< :Kq 8�2=< 8NZ � 8+pZ:Z6 B :KrtB4J BJ > : :6J B � ; � 8 ��: � � BD2VpG8 : 8 �?2o>�2!pG8�2XHt>�2o> 6 B :6J`J > : :=< 8�: >�H�2AB :cb B :Kq�:=< : �,8: B >��8�258.8 @CB @�< 8jRK2i:�@g>MJ : : >%LAB : � 8#q :K2=< 8�2XHt>72;> B4JKJ > 6 >�pZ:6J > 6 8 e 6 :ORX2i::cb B :Kq :=<g: 8jJ4d :NJ�<C6 :�Z0�@fZ 8 pG8 4X8�698jJ 8 Li:XH BD258.@ 8_HMRo8�2=<`BsZ

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� #

Page 61: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

��Li:XH BD2i: 4 :�@g>A@�<`Bg< RABD698 : >�2OJ d 8 @ 8�q LAB >�@�R6JWJ :)6 B : >M6 @CB >�258 �

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� � �

Page 62: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

��Li:XH BD2i: 4 :�@g>A@�<`Bg< RABD698 : >�2OJ d 8 @ 8�q LAB >�@�R6JWJ :)6 B : >M6 @CB >�258 �

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� ��§

Page 63: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

m6/ ,5!$x)/�1w1 !Wy�/ ,%/\3 #^x)/\#^xz( �V/N] ] (%xz/ 8 B4J � = � � = � � � = �.8 @ 8_H%R58-4�B pi8Z6 @ 8q :K2tB4L�>%J : 5B >�2AB 4�B0</8 @�< > @�R RK2 LZ6 >�H�6 :Kq�q : LZ6 BDq�: 4K8cJ`J4d 8 �?8�<><`B pZ:< 6 :54FR 5B >�258=4X8cJ =�� ��� � � BD2 � � �+� ��^Z B : >7q :X254�B�4IB q :X2AB4L�>%J : 5B >�258LZ698�2o4X>72;> B4J 2o>�q�8�4�B 7 8 = �+� � 8 � � 7 ��� � = � � = ��� � = �XZ BsJ�LZ698kLZ6 > : 8 @g@g> 6 88 @ 8_H%R58OJ 8 q :X2AB4L�>%J : 5B >�2AB BD254�B : :=</8 4 :NJWJ 8 4�BD698 <~<`B pG8 8 4 8cJ BDq�B 2i: UFR58 @�< 8R6J�<`BDq�8�4 :6JN< 8 @�< >KZ 0�@g@ 8$@g>�2o> 87 � UVF ^NGG\IHIL � � � $ � � � � $ � 8 Lt8Z6,q�8�<></8 4�B�BD2o@ 8Z6 BD698 � 258cJ L6RX2=< >B 2 : RAB : >7q Li:Z698 ��B4J �'J 8 @g> 6IHX8�2f</8 4�B�2o>�q�8 � � $ �,4K8�<>< > 8 � ��� � 7 �@ � � � Z ?I8)B4J �9J 8 : >7q LG:Z698�ej6 : LG:Z698�2=< 8 @CB ��� UFR58 @�< >=pXB 8�258 : 8�6 : :f< >2o8cJWJ 8�4IBD698 : < > 6 ��4�B�@CB @�</8�q�: �,4K8 �]2ABg< 8�4 :6J : >�q LAB J :=< > 698�� �S@ 8-BD2 pi8 : 8: >7q LG:Z698 e 6 : BS4X>%L6LAB :6LAB : B � � J : 6 B : 8�6 : :�pXB 8�258�8 �?8�<><hRG:=< : LZ6 B q :2o8cJWJ : 4�BD698 : < >M6 � : > 6,698Z2=</8.8 L�> B B 2�UFRo8cJWJ 8�4�B @CB @�</8Zq :�Z

0�@fZ 8 � UVF ^NGG\IHIL � UtR�TiaMJ�LME � N b �7 � HILtYSUVFSL � ������� � $ �'� � 8 : Li:Z6E< BD6 8 4 :NJWJ : J BD258;: @�R :�: 8 @g@CB pZ:: UFR58kJWJ : B 2 : RAB J : 4�BD698�<><`B pZ: : >�q Li:Z6 8 � < R=<></8 J 8 pG>%J�< 8:kb 8 J4d B 4X8�2=<`B�� : :=< >M698 � ������� � : >�2VpG8�2 5B >72G:6J q�8�2f</8 B 2 J 8�<></8�6 8q�:AB4Ro@ : >%J 8�� : >7q Li:Z698 2o8cJ �9J 8 @g>M6¤HA8�2=< 8 � � ���]1 8 : q�8�2o> :kb 82;>72 : >�q Li:AB : :NJWJ4d BD2=< 8�6,2;> 4�BQRX2i: @�< 6 BD2=HM: � pXB 8�258.@g>A@�<`Bg< RABg< > : >�20J :@ 8_UFR58�2 : 4�B : :Z6 :=<></8�6 B � $ �'� � Z�? >�2o> LZ698 4X8 �?2tBg< B^H%J B B 4K8�2=<`B�� : :=< > 6 B

� ��� 8 26RKq 8�6 > 4�B+J BD258V: : >M6,698�2f</8 �� � � 8 2o>�q�8.4K8cJ �'J 8 � ���� � 8 4 :=<g: : > 6,6 8�2=< 8 �� �� � 8 > 6 : : >M6,698�2f</8NZ

0�@fZ 8 � HILtYSUVFSL � � N������ �

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� � �

Page 64: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

Y�GMRME�a � � � !�� Y�GMRME�a � � � N������ �"!7 � HILtYSUVFSL � ������� � � ����� " $'� � �+( � ��� � � $ �'� � 8 >%J�< 698 :6J`J : @g>t@�< B��

< R 5B >�258�4�B � ������� : >�q�8 258cJ : :o@g> LZ6 8 : 8 4K8Z2=</8 ��H%J B :Z6¤Ht>7q 8�2=<`B� � ���#"%$'� � � ( ����� :cb 8 : >7q LG:AB >�2o> � @ 8cLi:Z6 :f< B 4 : pXBD6¤Ht>%J 8 � ej6 :LG:Z698�2=< 8 @CB ��� 4X>%L�> � � � ��� 8 :6JWJ4d B 2=</8Z6,2o> 4IB � $ �'� � ��@ :Z6 :K2K2o>@g>t@�<`Bg<hRtBg< B 4 :=HMJ B :Z6¤Ht>7q 8�2=<`B 8 �?8�<>< B p�:Xq�8�2=< 8 @�Lt8 : B�� : :=< B 4X>%L�>� � ����� 258cJ�< 8 @�< > 4K8cJ'LZ6 >�H76 :Xq�q : � � � �]1 8 ej6 : � � ����� 8 J :LG:Z698�2=< 8 @CB d �_de2o>72 : B 4K8CpG>�2o> 8 @g@ 8�6 8 @�Li: 5B�� :NJWJ4d BD2=< 8�6,2;> 4�B � $ �'� �q 8�<~< 8�698�J 8�>%L6L�>M6I< RK258jLi:Z698�2f</8 @CB ��Z

0�@fZ 8 � HILtYSUVFSL � � � E 1jP � � � E � � � P � � E d P �� � � � � � � �)1 T � a � ! � � � � � � � � � � � T � a � � � � � dT � a � !

7 � \MFIHILtY � ������� 8 : :X2 : 8cJWJ :�� : Li:Z6I<`BD698 4 :6JWJ : J BD258;: BD2 : RAB: >7q LG:Z698 � J4d 8 �?8�<>< > 4�B RK2i: 4IBD698�<>< B p�: � HILtYSUVFSL � �������LZ6 8 : 8 4K8Z2=</8�Z

0�@fZ 8 � \MFIHILtY �

7 � UGYMHILtY � ������� f � LGFIHSUGYQ8 J : Li:Z6I< 8�4�B �9J 8�@g>M6¤HA8�2=< 8 : >�q LZ698�@ :ej6 : � UGYMHILtY 8 � LGFIHSUGY pKB 8�258 BD2 : JWRo@ : @g>%J > @ 8 � ������� �8=@�<g:=<g:LZ6 8 pG8�2=<`B pZ:Kq�8�2=< 8.4K8 �]2ABg<g: � q�8 4�B :K2=< 8 � HILtYSUVFSL � Z

7 � UGYtFIHILtY � ������� f � LGFIHSUGYQ8 : >7q�8 � UGYMHILtY q : @ 8 � ��������� � �8.@�< :=<g:0LZ698 pG8�2=<`B pZ:Kq�8Z2=</8�4K8 �]2ABg<g:�Z

0�@fZ 8 � UGYtFIHILtY �

� HILtYSUVFSL � � N������ �� LGFIHSUGY

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� � �

Page 65: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

7 � UGYIf � L2GIUGYIf � L2G�TXLMf � LGFIHSUGY98 J : @CBD2f< :o@g@CB �8� UGY $ � � � $ � � � �#�!$���'� �����'� �#� �� L2GIUGY $ � � � $ � � ���#�!$ &���'� �����'� �#� �� � L2GIUGY $ � � � $ � � � �#�!$ * �� ��� � ������� �#� � �,,� � L2G�TXL �� ��� � ������� �#� � �� LGFIHSUGY

4A>�pG8 $ � � � $ � � � � �!$'( $ � � � $ � � ���#�!$ &'( ����� @g>�2o>!8 @�LZ698 @g@CB >�2AB : >t@�<g:K2=<`BsZ� : J >�HIB : : 4IB2e>RK2 5B >72G:Kq�8�2=< > �8jJ :!@�< 8 @g@ :!4�B�UFR58cJWJ : 4X8cJWJ4d B @�< 6)R 5B >�258UGYIfML2G�TXL UGYIfML2G�TXLF8 pXB 8�258 BD2 : JWRo@ :�@g>MJ > J :OLG:Z6I</8�4�B �'J 8.@g>M6¤HA8�2=< 8� �'� ������� � � � @�R :�: 8 @g@CB p�:�:6JWJ : LZ6 B q :�8 @�LZ698 @g@CB >7258 pG8�6 : �Q> : � L2G�TXL @ 82o8 @g@�RK2i:�4K8cJ`J 8�8�@�LZ698 @g@CB >�2AB �8$pG8�6 : ��Z$ � � � $ � � ���#�!$ ( $ � � � $ � � � �#�!$ & ( � ��� LZ>A@g@g>�2o>):X2 :cb 8�8 @g@ 8�698.4K8kJ6<`B4L�>

HILtYSUVFSLtH � HILtYSUVFSLtH � � � ���2o8cJQUFRi:6J : :o@g> J4d 8 @�LZ698�@g@CB >72o8 �8#pG8�6 :=@ 8 J4d B 4K8�2=<`B�� : :=< > 698 � �������6 B @�R6J�<g: 6 B @�Lt8 <~<`B pZ:Kq�8�2f</8 4K8 �?2AB < > � HILtYSUVFSLtH � > 2o>72 4X8 �?2tBg< >� � HILtYSUVFSLtH � Z

7 � L�JMJ�R�J "%$ � � � � � � � 8 >7rKrNJ B HK: B4J : >�q LAB4J :=< >M698 : B 2=</8Z6,6 >�q Lt8�6 8J : : >�q LAB J : 5B >72o8 :6J`J : J BD258;: BD2 : RAB J : 4IBD698�<>< B p�: : >�q Li:Z698 8 :pXB @�RG:6J B V:Z6 8#B4JSq�8 @g@ :XH�H B > "%$ � � � � � � � Z

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� ��B

Page 66: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

7 � GIUVFSL � ��" $�� � � � � " $ � 8 4X>ZpG8 � ��"%$ � � �8jRK2G: : >t@�<g:K2=< 8 B 2=</8Z6 :LZ>A@CB < B pZ: 8 � � " $ �8 RK2�B 4K8Z2=< B � : :f< >M698.4�B �9J 8NZ �0 8�UFRtB pZ:6J 8�2=< 8!: 8� HILtYSUVFSL � ��� � � "%$�� �� � HILtYSUVFSL � � � �!� " $ �

7 � c J�E � � E � � $ � ��� ��� 8 L�8�6,q�8 <~< 8 4�B 4M:Z698 :6J : >7q LtB4J :=< > 698 J :4IBD698�<>< B p�: @�L�8 : B :NJ 8 � � $ � � � �� :kb 8 4�B4L�8�254K8 4 :6J LG:Z6I< B : >MJ :Z698: >7q LtB4J :=< > 698�Z

� �¦���� ��¦�� ��¢$�I� �4� ����K¡��£�w�z����������\� � #

Page 67: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

� ��� �w ����

m\!$t^x)/�x~!`/ 8 @g>72o> 4K8GB �9J 8 :cb 8 6 :=H�H�6)R6L6LG:K2o> BD2o@CB 8Zq�B[4�B �'J 8 � � �+� � � : >�2e:NJ : RK258eBD2=e > 6,q :GB >�2AB :XH�H B4RK2f< B pG8�UFRi:6J BkRK2i:a<g:Vp5>MJ : 4K8iB : >�2=< 8�26R=<`B��: >t@�< B <hRAB < B�4 : e~RK2 5B >�2AB : >72 : >�q LABg<`B.@�Lt8 : B � : B � L�Z 8NZ RK2i: J BDrZ698Z6 B :4�B e~RK2GB >�2AB Lt8�6 B4J < 6 :=<>< :Xq�8�2=< > 4K8kJWJ 8 @�<C6 BD2XH b 8�� Z 78�6=8 �?8�<><hRi:Z6 8RK2i: :cb B :Kq :=<g: : RX2i: e~RK2 5B >�258 4IB J B rZ698�6 B : �8 258 : 8�@g@ :Z6 B > : >72o>t@ : 8�6 8LZ698 pG8�2f< B pZ:Kq 8�2=< 8 B4J 2o>7q 8 4K8cJWJ : e~RX2 GB >7258 � B4J 26RKq 8�6 > 8 B4Jj<`B4L�>4K8_H%J B�:Z6IHA>�q�8�2=<`B 8 �-258kJ : >7q�:K254X> 4�B : >�q LAB J : 5B >72o8 �!@�L�8 : B�� : :Z698 :UFRi:NJ 8 J BDrZ6 8�6 B : @CB�e : 6 B e 8�6 BDq 8�2=< >5Z � H�2AB : >7q LtB4J :=< > 698 pXB 8�258 e > 6,2tBg< >: >�2 RK2 : 8�6I< > 26RKq 8�6 > 4�B J BDrZ6 8�6 B 8 �,4�B)@CB @�</8�q�: � 258 : 8 @g@ :Z6 B 8 :6J`J :HA8�258�6 :GB >�258)4K8cJWJ d 8 @ 8_H%RABDrAB4J 8 :o@g@g> : B :f< > :6J]@g> 6¤HA8�2=< 8)4K8cJ LZ6 >�H�6 :Kq�q�:��q : :X2 :cb 8 J4dsR=< 8�2=< 8 L6R��> : >t@�<C6)RtBD698 J 8 LZ6 >%LZ6 B 8 J B rZ698�6 B 8 : Li:Z6I<`BD698 4M:AB@g> 6IHX8�2f< B : >�2=< 8�258�2f< B J 8 e~RX2 GB >72AB_4 : BD2;@ 8�6 BD698 � J : q >�4 :NJ Bg< �: 4IB4Lt8�2o4K84 :6JK@CB @�< 8�q : � Z � 8 J BDrZ698�6 B 8 LZ>A@g@g>�2o>�8�@g@ 8�698

7 � ; � 8 ��: � 8 J 8 e~RK2 5B >�2AB$4�B�J BDrZ698�6 B : : : RAB�@CB e : 6 B e 8�6 BDq 8�2=< > 2o8cJ@g>M6¤HA8�2=< 8+pG8�2XHt>72;>�B 2o@ 8�6 Bg< 8 �A4FRK6 :K2=< 8 J :�e :o@ 8 4�B � 8 � � �K4�B 698�<>< :Kq 8�2=< 8:NJWJ4d BD2=< 8�6,2;> 4K8kJ �'J 8#8 @ 8_H%RABDrAB4J 8NZ � d 8 @�< 8�2o@CB >�258�<`B4LAB : :=4K8cJWJ 8 J BDrZ698Z6 B 8@�<g:=<`B :cb 8 �8 NgE @g>c<~< > � 2tB � 8 N GIUVP @g>c<~< >�� BD254A>�� @�D

7 798 � ; � 8 ��: � 8 J : e~RK2 5B >�2AB 4�B J BDrZ6 8�6 B : 2o>�2 pG8�2=HA>�2o> BD2;@ 8�6 Bg< 82o8cJWJ4d 8 @ 8�HMRAB rAB4J 8 �]:6J9J >M6 > LZ>A@�< > : d �8ORK2 ��LNRK2=<g:=< >M698�� :cb 8OL�8�6,q�8�<>< 84IB 698 : R6Lt8Z6 :Z6)J 8 4 :6J`J : J BDrZ698�6 B : 4�BD2G:Kq�B : : 8 : :Z6 B : :Z6zJ 8 BD2 q 8�q > 6 B :

� ��z���z�}�¥� � �

Page 68: Dipartimento di Fisica - System and Network Administrationroberto/Materiale/c.pdf · q:!pxb 8z258:o@g@ 8 _h 2i: =< > b 4j apz: 6j >m698 s z 2i:=pz:z6 b:krab j 8 4 b

4MRK6 :K2=< 8 J d 8 @ 8 : R 5B >�258 �"UMRi:K254X> pG8�2XHt>72;> :kb B :Kq :f</8NZ B 2 UFRo8 @�< >q�> 4A> HMJ B 8�@ 8_HMRtBDrAB4J B 4K8iBaLZ6 >�H76 :Kq�q�B b :K2X2o> 4�BDq�8Z2o@CB >�258 q�BD2o>M6988 LAB��R 8�@ 8_HMRtBDrAB4J BlL�>t@g@g>72o> : >7254IB pXB 4K8�698 J 8 @�< 8 @g@ 8 J BDrZ698�6 B 8 @ 8�2 :rtB @g>�H�2o> 4IB : pi8Z6,258 RK2i: : >%LAB : LZ6 B pZ:=<g:�Z � d 8 @�< 8�2o@CB >�258 <`B4LAB : :�4K8cJ`J 8J BDrZ698�6 B 8�4�B 2i:Kq�B :kb 8 �8 N TXR @g>c<>< > � 2AB � 8 NjH�G2G @g>c<~< >�� BD254A>�� @�D

m\!$t^x)/�x~!`/�!s* ��������� 8 :�4�B��?8�6 8�2 : 4IB :NJ�<C6 BVJ B 2XHMRG:XH�H B��tB4J�A-8+B4J�A � � BD2@ 8�2o@g> @�< 698�<>< >)2o>�2 b :X2K2o> 258�B @�< 6)R 5B >72tBMLt8Z6 J4dEB S � 2o8�B @�< 6)R 5B >�2ABML�8�6�J 8>%Lt8�6 :GB >�2ABlq�:=</8Zq :=<`B :cb 8 : >�q L6J 8 @g@ 8 �Q@g>MJ > J 8�>ML�8�6 : 5B >�2ABM:Z6 B <Cq�8 < B :kb 8e >�254 :Kq 8�2=<g:6J B�� Z � R=<></8 UFR58 @�< 8 e~RX2 GB >72i:NJ Bg< �:���8 q�>MJ�< 8 :NJ�<C6 8 ��@g>72o>: :�: 8 @g@CBDrAB4J B|< 6 :Kq�Bg< 8 :kb B :Kq :f</8=: >%L6L�>M6I< RK258Oe>RK2 5B >72tB�4�B�J BDrZ698�6 B :�Z � 8J BDrZ6 8�6 B 8 e >M6,2ABg< 8 : >72 B4J : >�q LAB J :=< > 698-@g>�2o> : :_: >7q Li:XH�2i:=< 8�4 : 8 � ��� � 7 �@ � � �,8 @�</8Z2o@CB >�258 < B LAB : : N b �-BD2 : RAB @g>�2o> 4IB :cb B :Z6 :=< B_B LZ6 >c< >c<`B4LAB 4K8cJ`J 8e~RK2GB >�2AB 4�BTJ BDrZ698Z6 B : 8 4X8 �?2tBg</8_8 pG8�2f<hRi:NJ B� ; � = ^Z 6 BDq�: 4IBrR;@ :Z698 RK2i: 4�BUFR58�@�</8 e>RK2 5B >72tB��8�UFRABD254IBI2o8 : 8 @g@ :Z6 B >#BD2 : JWR54K8Z698 �,4�BD698�<><`B pZ: � UVF ^NGG\IHIL �B 698cJ :=<`B pXBSBD2 : JWRo4K8 �9J 8NZ

� UVF ^NGG\IHIL � Tia H�GIUVPeN b �� EIUVF ����

^ b E�J � TiaMJ UVF���E � �� � � � !UVF a UVF a�L�J�R � E�a�RIU � TiaMJ UVF���E � ! fMf UVF a�L�J�R P E2GML � � �

� ��z���z�}�¥� � �