19 july 2006ken moffeit1 comparison of 2mrad and 14/20 mrad extraction lines ken moffeit (via eric...

19 July 2006 Ken Moffeit 1

Comparison of 2mrad and 14/20 mrad extraction lines

Ken Moffeit (via Eric Torrence)VLCW06

19 July 06


BDS Layout

2 mrad

14/20 mrad


14/20 mrad Extraction Line

250 GeV

45.59 GeV2 mrad energy

stripe

2 mradenergy stripeBVEX1E

z=46.782 m

SynchrotronRadiation Shielding

for Cerenkov Detector

z=164.25x=12.25cm

Energy Chicane Polarimeter Chicane10 cm

10 meters

Synchrotron Stripe

Detector

z=147.682x=0 y= -19.85

Cerenkov Detector

z= ~175 m

Wiggler

Low Field

25.1 GeV

BVEX2Ez=49.082 m

BLEX1z=51.382 m

BLEX2z=53.982 m

WEX1z=52.682 m

BVEX3Ez=55.282 m

BVEX4Ez=57.582 m

BVEX5Ez=59.882 m

BVEX6Ez=62.182 m

BLEX3z=64.482 m

BLEX4z=67.082 m

WEX2z=65.782 m

BVEX7Ez=68.382 m

BVEX1Ez=70.682 m

BVEX1P

z=120.682 m

BVEX2P

z=140.682 m

BVEX3P

z=152.682m

BVEX4P

z=172.682 m

Compton IP

31.2 GeV

Synchrotron Stripe

Detector z= 147.682 mx=0 y=15.3cm

VacuumChamber

VacuumChamber

Synchrotron Radiation limit toCherenkov Detector

14 cm

17.8 cmQDEX1A

z=6.0 m

QDEX1Bz=7.941 m

QFEX2Az=9.881 m

QFEX2Bz=15.5 m

QFEX2Cz=17.943 m

QFEX2Dz=20.386 m

QDEX3Az=22.829 m

QDEX3Bz=25.235 m

QDEX3Cz=27.641 m

QDEX3Dz=30.047 m

QDEX3Ez=32.453 m

QFEX4Az=34.858 m

QFEX4Bz=37.103 m

QFEX4Cz=39.348 m

QFEX4Dz=41.593 m

IP

-0.75mrad

0.75

m rad

QFEX4Ez=43.838 m


2 mrad Extraction LinePolarimeter Chicane

Plan View

10 m

10 cm

BHEX2

z=163.778 m

x=80.38 cm

BHEX2

z=166.077 m

x=81.63 cm

Angle2.0 mrad at IR

QEX1A

z=34.6799 m

x=14.98 cm

QEX1B

z=37.9798 m

x=16.81 cm

BHEX1

z=44.580 m

x=20.45 cm

Angle -3mrad

5 cm

-5 cm

0

Angle 3mrad

ElevationView

QEX3

z=127.678m

x=62.24 cm

QEX3

z=130.978 m

x=63.902 cm

Beam StayClear +- 7.5 cm

Photon BeamstrahlungCone

+- 0.5 mrad

Energy Chicane

Wiggler

QEX4

z=138.778 m

x=67.820 cm

-10 cm

10 cm

2 mrad extraction line

Angle 5.023 mrad

BYCHIC

z=66.179 m

x=31.351 cm

Angle3 mrad

17.8 cm

CherenkovDetector

25.1 GeV

Dispersion = 69mm250 GeV

QF1

z=15.868 m

x=0 cm

HCOLL+-7.5cm

z=61.57 mx=29.041 cm

VCOLL+-1.2cm

z=61.87 mx=29.191 cm

BYCHIC

z=68.48 m

x=32.507 cm

BYCHIC

z=70.78 m

x=33.662 cm

BYCHICM

z=89.179 m

x=42.905 cm

BYCHICM

z=91.479 m

x=44.060 cm

BYCHICM

z=93.779 m

x=45.216 cm

VCOLL2+-5cm

z=95.779 mx=46.220 cm

Dispersion = 69 cm250 GeV

VCOLL+-7.5cm

z=153.578 mx=75.254 cm

ECOLL0+-7.5 cm

z=240.276 mx=129.471 cm

HCOLL2+-5 cm

z=118.479 mx=57.623 cm

BYCHIC

z=119.079 m

x=57.924 cm

BYCHIC

z=121.379 m

x=59.080 cm

BYCHIC

z=123.679 m

x=60.235 cm

QEX4

z=142.078 m

x=69.478 cm

QEX4

z=145.378 m

x=71.135 cm

QEX4

z=148.678 m

x=72.793 cm

QEX5

z=159.778 m

x=78.369 cm

QEX5

z=156.478 m

x=76.711 cm

Angle 5.740 mrad

Angle 6.458 mrad

BYCHICM

z=96.079 m

x=46.371 cm

BYCHICM

z=98.379 m

x=47.526 cm

BYCHICM

z=100.679 m

x=48.681 cm

BYENE

z=169.078 m

x=83.492 cm

BYENE

z=171.378 m

x=84.977 cm

BYENE

z=173.678 m

x=86.463 cmBYENEM

z=192.077 m

x=98.345 cm

BYENEM

z=194.377 m

x=99.830 cm

BYENEM

z=196.677 m

x=101.315cm

BYENEM

z=198.977 m

x=102.801cm

BYENEM

z=201.277 m

x=104.286cm

BYENEM

z=203.577 m

x=105.771cm

Angle-3 mrad

Wiggler

BYENE

z=221.977 m

x=117.653cm

BYENE

z=224.277 m

x=119.138cm

BYENE

z=226.577 m

x=120.624cm

Wiggler

BHEX3

z=240.876 m

x=129.858cm

BHEX3

z=243.176 m

x=131.199cm

BHEX3

z=245.476 m

x=132.283cm

BHEX3

z=247.776 m

x=133.110cm

ECOLL0

+-7.5 cm

z=240.276 m

x=129.471

cm

Photon BeamstrahlungCone

+- 0.5 mrad

BYPOL

z=250.776 m

x=133.822cm

BYPOL

z=253.076m

x=134.282cm

BYPOLM

z=260.776 m

x=135.822cm

BYPOLM

z=263.076m

x=136.282cm

BYPOLM

z=273.076 m

x=138.282cm

BYPOLM

z=275.376m

x=138.742cm

BYPOL

z=283.076 m

x=140.282cm

BYPOL

z=285.376m

x=140.742cm

12.3 cm

35 GeV

Angle2.0 mrad

Compton IPz=269.076mx=137.482cm

BHEX4

z=289.376 m

x=141.542cm

Dispersion = 20 mm250 GeV

ComptonIP

Shielding

QD0

z=4.5 m

x=0 cm

SD0

z=8.19 m

x=0 cm

SF1

z=18.38 m

x=0 cm

Angle 5.523 mrad

3.68 mrad5.0 mrad

3.54 mrad

Synchrotron Stripe Detectorz=269.076 my= -28.7 cm

Synchrotron Stripe Detectorz=269.076 my= 12.7 cm

Angle-2 mrad

Angle2 mrad

Synchrotron StripeDetectors


The extraction line transport is simulated using the program GEANT.

Disrupted beam events were taken from files prepared by Andrei Seryi.

For these studies files: cs11 corresponds to a normal ILC beam (mean energy 244.3 GeV and RMS 10.84 GeV)

cs13 with parameters set for large-y (mean energy 243.1 GeV and RMS 11.14 GeV).

cs13 dy = 4nm gives large-y parameter data sets with the centroid of the beams missing by 4nm in the vertical (mean energy 242.2 GeV and RMS 12.05 GeV)

cs13 dx =200nm has beams missing by 200nm in the horizontal (mean energy 243.3 GeV and RMS 10.94 GeV)


Spin Precession

bendbendspin

GeVEg θθγθ ⋅=⋅−

=44065.0

)(2

2

Change in spin direction for various bend angles and the projection of the longitudinal polarization. Electron beam energy is 250 GeV.

Change in Bend Angle Change in Spin Direction at 250 GeV

Longitudinal Polarization Projection

1 mrad 32.5 o 84.3%

275 rad 8.9 o 98.8%

100 rad 3.25 o =56mrad 99.8%


2mrad x vs y

+/-100 m


2mrad Extraction Line: Beam accepted and polarization projection for various +- 100 micron selections about the x value

of the beam at the Compton IP. In each case abs(y+2.0cm)<100 microns and abs(x-137.45).

x +- 100 microns

%Beam within +-100microns in x & y

Polarization Projection

137.45 14.7 99.83

137.47 6.0 99.89

137.49 4.8 99.94

137.51 3.8 99.94


20mrad Extraction Line with 2.019<y<-1.999cm and abs(x)<0.01cm

Condition (file name) %Beam within +-100microns in x & y


Nominal Beam Condition (cs11) 48.3 99.85

Large y (cs13) 36.7 99.76

Large y horizontal offset 200nm (cs13_dx200)

37.2 99.75

Large y vertical offset 4nm (cs13_dy4)

32.8 99.75

2 mrad Extraction Line with abs(y+2)<0.01cm and abs(x-137.45)<0.01cm

Condition (file name) %Beam within +-100microns in x & y


Nominal Beam Condition (cs11) 14.7 99.83

Large y (cs13) 7.6 99.83

Large y horizontal offset 200nm (cs13_dx200)

8.9 99.82

Large y vertical offset 4nm (cs13_dy4)

6.0 99.83


Beam Losses from the e+e- IR to the Compton Detector Plane

Condition (file name) Losses Beam Lost Beam

Nominal Beam Condition (cs11) 0 34883 <0.5 * 10-4

Large y (cs13) 0 30000 <0.6 * 10-4

Large y horizontal offset 200nm (cs13_dx200) 0 30000 <0.6 * 10-4

Large y vertical offset 4nm (cs13_dy4) 0 30000 <0.6 * 10-4

2 mrad Crossing Angle Extraction Line

Condition (file name) Losses Beam Lost Beam

Nominal Beam Condition (cs11) 4 30000 1.3 * 10-4

Large y (cs13) 9 30000 3 * 10-4

Large y horizontal offset 200nm (cs13_dx200) 7 30000 2.3 * 10-4

Large y vertical offset 4nm (cs13_dy4) 18 30000 6 * 10-4

20 mrad Crossing Angle Extraction Line


Beam losses were further studied by using a file with the tails of the disrupted beam having events with energy less than 0.65 of the beam energy or the angle greater than

0.5 mrad:

http://www.slac.stanford.edu/~seryi/ILC_new_gp_files/cs11_hs/tail1_lt_0_65E0_or_gt_500urad.dat

e+e- Interaction Point

Energy (GeV)X angle (milliradians)

y angle (milliradians)

0

0.2

-0.2

-0.5 0.50 100 160120 140

Beam Losses




Only 5899 of the 10,503 particles continue to the Compton Detector plane. This represents a loss of 2.62*10-4 of the 17.59 million original beam tracks.

2mrad extraction line

Estimate ~50 photons/cm2 are in the region of the Cherenkov counter cells for each bunch of 2*1010 electrons

Only ~20% above 10 MeV

Can reduce by local shielding of Cherenkov Detector

Compton Signal ~650 backscattered electrons per GeV or >1000 per 1cm cell


Synchrotron Radiation


Table IV: Energy Loss from Synchrotron Radiation between the e+e- IR and the Center of the Energy Chicane.

a) 20 mrad Crossing Angle Extraction Line

Condition (file name) Energy Loss (MeV)

Nominal Beam Condition (cs11) 119.4

Large y (cs13) 123.0

Large y horizontal offset 200nm (cs13_dx200) 122.7

Large y vertical offset 4nm (cs13_dy4) 124.3

b) 2 mrad Crossing Angle Extraction Line

Condition (file name) Energy Loss (MeV)

Nominal Beam Condition (cs11) 854.2

Large y (cs13) 854.2

Large y horizontal offset 200nm (cs13_dx200) 828.5

Large y vertical offset 4nm (cs13_dy4) 859.4


The 20 mrad extraction line has:

•Core of beam within +-100microns has between 32 and 48% of the beam.

•The polarization projection is 99.75 to 99.85% at the Compton IP.

•No beam losses from e+e- IR to Compton detector plane out of 17.6 million beam tracks.

•Beam energy loss due to synchrotron radiation to the middle of energy chicane (z=59.7 m) is only ~110 MeV and does not show variation with beam conditions.

•The collimator at z=164.25 meters needs to be designed. It absorbs the synchrotron radiation above the 0.75 mrad beam stay clear allowing the Cherenkov detector to begin at y~14 cm.

Conclusions


•There are large beam losses between e+e- IR and Compton detector plane (>2.6*10-4 are lost) giving secondary backgrounds of mainly photons in the region of the Cherenkov Detector.

•A small percentage of beam is hit by laser spot +-100 microns (~15%) at the Compton IP and results in low Compton luminosity.

•There are large beam energy losses (~850 MeV) due to synchrotron radiation between IR and the center of the energy chicane at z=198.82 meters.

•Synchrotron radiation at Cherenkov Detector is favorable. The detector only sees the synchrotron radiation from the magnets of the polarimeter chicane, and this is contained between -9 and +2 cm. The first cell of the Cherenkov Detector starts at +10 cm.

The 2 mrad extraction line has:

19 july 2006ken moffeit1 comparison of 2mrad and 14/20 mrad extraction lines ken moffeit (via eric...

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