lifetime measurements from exill-fatima campaign pietro spagnoletti university of the west of...
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Lifetime measurements from EXILL-FATIMA campaign
Pietro SpagnolettiUniversity of the West of Scotland
70 72 74 76 78 80 82 84 86 88 90 920
10
20
30
40
50
60
70
80
Ba isotopes
Neutron Number
B(E2
:0+
→2+
) [W
.u]
48 50 52 54 56 58 60 62 64 660
20406080
100120140160180200
Zr and Sr IsotopesZr Isotopes Sr isotopes
Neutron Number
B(E2
:0+
→2+
) [W
.u]
Shape coexistence in A~100 region
Shape coexistence in A~100 region
48 50 52 54 56 58 60 62 64 660
2
4
6
8
10
12
Zr Isotopes
Neutron Number
E(4+
)/E(
2+)
70 72 74 76 78 80 82 84 86 88 90 92 940
0.5
1
1.5
2
2.5
3
3.5
Ba Isotopes
Neutron Number
E(4+
)/E(
2+)
0+
2+
4+
0+
2+
4+
g.s.
1223
1436
1744
2048
2277
𝑬𝟒+¿
𝑬𝟐+¿≈𝟏 .𝟔𝟕 ¿¿
𝑬𝟒+¿
𝑬𝟐+¿≈𝟐 .𝟕𝟑 ¿¿
Ground state band
Deformed band(relative energy ratio)
0+
0+
2+
4+
4+
2+6+
g.s.
212
564
1062
331
878
1414
98Zr 100Zr
𝑬𝟒+¿
𝑬𝟐+¿≈𝟐 .𝟔𝟕 ¿¿
Ground state band
𝑬𝟒+¿
𝑬𝟐+¿≈𝟏 .𝟗𝟖 ¿¿
Band built on excited 0+ level(relative energy ratio)
EXILL-FATIMAEXOGAM@ILL – Fast Timing Array
• Prompt Gamma ray spectroscopy following neutron induced fission reactions
• Cold neutron flux 5*107 n s-1 cm -2
• 235U Target 0.8mg cm-2
(σcapture=99b) • 8 EXOGAM Clover Detectors • 16 LaBr3(Ce) fast
scintillators• Measurement of lifetimes
>10ps
Photo taken from: N. Saed-Samii, Diploma thesis, University of Cologne
EXILL-FATIMAEXOGAM@ILL – Fast Timing Array
• Prompt Gamma ray spectroscopy following neutron induced fission reactions
• Cold neutron flux 5*107 n s-1 cm -2
• 235U Target 0.8mg cm-2
(σcapture=99b) • 8 EXOGAM Clover Detectors • 16 LaBr3(Ce) fast
scintillators• Measurement of lifetimes
>10ps
Photo taken from: N. Saed-Samii, Diploma thesis, University of Cologne
*411keV
344keV
0+
2+
4+
152Gd
CFD
CFD
TAC
Delay
LaBr(Ce) Scintillation Detectors
Start
StopDAC
Mirror Symmetric Centroid Difference
3-
368keV
EXOGAM
CFD
CFD
TAC
Delay
LaBr(Ce) Scintillation Detectors
Start
StopDAC*
411keV
344keV
0+
2+
4+
152Gd
𝟐𝛕=|𝚫𝐂−𝐏𝐑𝐃|= Cstop - Cstart
Mirror Symmetric Centroid Difference
• Figure adapted from - J.-M Regis et al., Nucl. Instr. And Meth A 622 (2010) 83-92
• J.-M Regis et al., Nucl. Instr. And Meth A 763 (2014) 210-220
Analysis – First excited 2+ level of 100Zr
• Test case• High fission yield• Even-even nucleus• Measured several times previously• Relatively long lifetime• Mirror symmetric centroid shift method
and exponential decay measurements possible
4+
6+
212keV
564keV
1061keV
0+
2+
100Zr
497keV
352keV
212keV
Analysis
4+
6+
212keV
564keV
1061keV
0+
2+
100Zr
497keV
352keV
212keV
4+ → 2+
4+ → 2+
2+ → 0+
• Cut into the feeding transition for both the start and stop FT-matrices.
• Must determine to contribution from the background to the centroid shift.
• Measurement of centroid shift at energies above feeding transition.
𝜏2+¿=1
2|𝛥𝐶+𝛥𝐶−𝛥𝐶𝐵𝐺
𝛾−𝑃𝑅𝐷|¿
𝜏2+¿=780(10 )𝑝𝑠¿TACstop
𝜏2+¿=770(10)𝑝𝑠 ¿TACstart
=
B(E2; 0+ → 2+)exp = 83(1)W.u.B(E2; 0+ → 2+)ensdf = 75(4)W.u.
𝜏2+¿=1
2|𝛥𝐶+𝛥𝐶−𝛥𝐶𝐵𝐺
𝛾−𝑃𝑅𝐷|¿
𝜏2+¿=780(10 )𝑝𝑠¿TACstop
𝜏2+¿=770(10)𝑝𝑠 ¿TACstart
=
B(E2; 0+ → 2+)exp = 83(1)W.u.B(E2; 0+ → 2+)ensdf = 75(4)W.u.48 50 52 54 56 58 60 62 64 66
020406080
100120140160180200
Zr and Sr IsotopesZr Isotopes
Neutron Number
B(E2
:0+
→2+
) [W
.u]
99Zr12
+¿¿
32
+¿ ¿
72
+¿ ¿
92
+¿ ¿
112
+¿ ¿
132
+¿¿
152
+¿ ¿
()
52
+¿¿
72
+¿ ¿
32
−
192
−
152
−
112
−
52
−
72
−
121.7
252.0
657.9
850.5
1065.71038.5
1255.9
1507.4
1970.8
1802.6
1236.6
821.6
614.1
678.6
667.5
g.s.
1322.8
1892.8
92
+¿ ¿
132
+¿¿
112
+¿¿1585.5
T1/2=54ns
32
+¿ ¿
575.7
99Zr12
+¿¿
32
+¿ ¿
72
+¿ ¿
92
+¿ ¿
112
+¿ ¿
132
+¿¿
152
+¿ ¿
()
52
+¿¿
72
+¿ ¿
32
−
192
−
152
−
112
−
52
−
72
−
121.7
252.0
657.9
850.5
1065.71038.5
1255.9
1507.4
1970.8
1802.6
1236.6
821.6
614.1
678.6
667.5
g.s.
1322.8
1892.8
92
+¿ ¿
132
+¿¿
112
+¿¿1585.5
T1/2=54ns
32
+¿ ¿
575.7
• W. Urban, J.A. Pinston, et al., Eur. Phys. J. A 16, 11-15 (2003)
• 3 different deformations present within 1MeV
• Spherical at low energy
99Zr12
+¿¿
32
+¿ ¿
72
+¿ ¿
92
+¿ ¿
112
+¿ ¿
132
+¿¿
152
+¿ ¿
32
+¿ ¿
32
−
192
−
152
−
112
−
52
−
72
−
121.7
252.0
657.9
1038.5
1255.9
1507.4
1970.8
1802.6
1236.6
821.6
614.1
678.6
667.5
g.s.
T1/2=54ns
• Excited state at 1038.5keV interpreted to be K-isomer.
• 9/2[404] neutron hole excitation
• Large deformation β2=0.41
135I
112
+¿¿
72
+¿ ¿
152
+¿¿
172
+¿ ¿
135I82
𝑔7 /2⊗2+¿ ¿
𝑔7 /2⊗4+¿ ¿
1134
1421
1994
4+
6+
1279
1576
1691
0+
2+
134Te82
0+
2+
136Xe82
4+
6+
1313
1694
1791
Summary and Future work• Analysis ongoing• Lifetime measurements of excited states in three different
bands of 99Zr performed• Two lifetime measurements for excited states of 135I performed• Calculations of reduced transition probabilities still to be done• Analysis of 97Sr, 98Sr, 133I and other• Analysis of data produced from 241Pu target
Fission product yield
Thanks to the EXILL-FATIMA Collaboration
• TU Darmstadt, Germany• S. Ilieva, S. Bönig, A.-L. Hartig, C. Henrich, A. Ignatov, Th. Kröll, M. Thürauf• Universität zu Köln, Germany• J. Jolie, J.-M. Régis, N. Saed-Samii• ILL, Grenoble, France• A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, W. Urban• GANIL, France• G. de France• IPHC Strasbourg, France• R. Lozeva• University of the West of Scotland, Paisley, UK• M. Scheck, G. Simpson, J. F. Smith, P. Spagnoletti• CSNSM Orsay, France• C. Petrache, R. Leguillon, T. Zerrouki, S. Kaim, Ks. Rezynkina• IFIN-HH, Bucharest, Romania• N. M˘arginean, D. Filipescu, I. Gheorghe, D. Ghita, R. Lica, R. M˘arginean, C. Mihai, S. Toma• University of Surrey, Guildford, UK• P.H. Regan, R. Carroll, Zs. Podoly´ ak, C. Townsley, P. Walker, W. Catford, T. Alharbi• Universidad Complutense, Madrid, Spain• L. M. Fraile, V. Paziy ...