comparison of 2mrad and 14/20 mrad extraction lines

27 June 2006 Ken Moffeit 1

Comparison of 2mrad and 14/20 mrad extraction lines

Ken MoffeitILC BDS

27 June 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 Detectorz=164.25

x=12.25cm

Energy Chicane Polarimeter Chicane10 cm

10 meters

Synchrotron StripeDetector

z=147.682x=0 y= -19.85

Cerenkov Detectorz= ~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

BVEX1Pz=120.682 m

BVEX2Pz=140.682 m

BVEX3Pz=152.682m

BVEX4Pz=172.682 m

Compton IP

31.2 GeV

Synchrotron StripeDetector z= 147.682 m

x=0 y=15.3cm

VacuumChamber

VacuumChamber

Synchrotron Radiation limit toCherenkov Detector

14 c

m1

7.8

cm

QDEX1Az=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

QFEX4Ez=43.838 m


2 mrad Extraction LinePolarimeter Chicane

Plan View

10 m

10 cm

BHEX2z=163.778 mx=80.38 cm

BHEX2z=166.077 mx=81.63 cm

Angle2.0 mrad at IR

QEX1Az=34.6799 mx=14.98 cm

QEX1Bz=37.9798 mx=16.81 cm

BHEX1z=44.580 mx=20.45 cm

Angle -3mrad

5 cm

-5 cm

0Angle 3

mrad

ElevationView

QEX3z=127.678mx=62.24 cm

QEX3z=130.978 mx=63.902 cm

Beam StayClear +- 7.5 cm

Photon BeamstrahlungCone

+- 0.5 mrad

Energy Chicane

Wiggler

QEX4z=138.778 mx=67.820 cm

-10 cm

10 cm

2 mrad extraction line

Angle 5.023 mrad

BYCHICz=66.179 mx=31.351 cm

Angle3 mrad

17.8

cm

CerenkovDetector

25.1 GeV

Dispersion = 69mm250 GeV

QF1z=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

BYCHICz=68.48 m

x=32.507 cm

BYCHICz=70.78 m

x=33.662 cm

BYCHICMz=89.179 mx=42.905 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

BYCHICz=119.079 mx=57.924 cm

BYCHICz=121.379 mx=59.080 cm

BYCHICz=123.679 mx=60.235 cm

QEX4z=142.078 mx=69.478 cm

QEX4z=145.378 mx=71.135 cm

QEX4z=148.678 mx=72.793 cm

QEX5z=159.778 mx=78.369 cm

QEX5z=156.478 mx=76.711 cm

Angle 5.740 mrad

Angle 6.458 mrad




BYENEz=169.078 mx=83.492 cm

BYENEz=171.378 mx=84.977 cm

BYENEz=173.678 mx=86.463 cm

BYENEMz=192.077 mx=98.345 cm

BYENEMz=194.377 mx=99.830 cm

BYENEMz=196.677 mx=101.315cm

BYENEMz=198.977 mx=102.801cm

BYENEMz=201.277 mx=104.286cm

BYENEMz=203.577 mx=105.771cm

Angle-3 mrad

Wiggler

BYENEz=221.977 mx=117.653cm

BYENEz=224.277 mx=119.138cm

BYENEz=226.577 mx=120.624cm

Wiggler

BHEX3z=240.876 mx=129.858cm

BHEX3z=243.176 mx=131.199cm

BHEX3z=245.476 mx=132.283cm

BHEX3z=247.776 mx=133.110cm

ECOLL0+-7.5 cm

z=240.276 mx=129.471

cm

Photon BeamstrahlungCone

+- 0.5 mrad

BYPOLz=250.776 mx=133.822cm

BYPOLz=253.076mx=134.282cm

BYPOLMz=260.776 mx=135.822cm

BYPOLMz=263.076mx=136.282cm

BYPOLMz=273.076 mx=138.282cm

BYPOLMz=275.376mx=138.742cm

BYPOLz=283.076 mx=140.282cm

BYPOLz=285.376mx=140.742cm

12.3

cm

35 GeV

Angle2.0 mrad

Compton IPz=269.076mx=137.482cm

BHEX4z=289.376 mx=141.542cm

Dispersion = 20 mm250 GeV

ComptonIP

Shielding

QD0z=4.5 mx=0 cm

SD0z=8.19 mx=0 cm

SF1z=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

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 an

gle

(mill

iradi

ans)

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


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:

comparison of 2mrad and 14/20 mrad extraction lines

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