Final Focus Synchrotron Radiation M. Sullivan for the JLEIC Collaboration Meeting Mar. 29-31, 2016

JLEIC Collaboration Meeting Mar. 2016 Outline Brief Introduction Beam parameters SR from the final focus elements Synchrotron Radiation backgrounds Results from 3 accelerator options Total photons and power from FF SR Smaller IP beam pipe? Summary Conclusion JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Accelerator The EIC accelerator design(s) have large beam energy range(s) for both beams 5-20 GeV for e- 20-250 GeV for the ions This flexibility must be carefully observed when designing IR details SR for the electron beam is a good example JLEIC Collaboration Meeting Mar. 2016

Electron IR Parameters JLEIC current baseline design parameters Electron beam Energy range 3-10 GeV Current (5/10 GeV) 3/0.7 A Beam-stay-clear 12 beam sigmas Emittance (x/y) (5 GeV) (14/2.8) nm-rad Emittance (x/y) (10 GeV) (56/11) nm-rad Betas x* = 10 cm x max = 300 m y* = 2 cm y max = 325 m Final focus magnets Name Z of face L (m) k G (10 GeV-T/m) QFF1 2.4 0.7 -1.3163 -43.906 QFF2 3.2 0.7 1.3644 45.511 QFFL 4.4 0.5 -0.4905 -16.362 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Ion IR Parameters Proton/ion beam Energy range 20-100 GeV Beam-stay-clear 12 beam sigmas Emittance (x/y) (60 GeV) (5.5/1.1) nm-rad Betas x* = 10 cm x max = 2195 m y* = 2 cm y max = 2580 m Final focus magnets Name Z of face L (m) k G (60 GeV) QFF1 7.0 1.0 -0.3576 -71.570 QFF2 9.0 1.0 0.3192 63.884 QFFL 11.0 1.0 -0.2000 -40.02 JLEIC Collaboration Meeting Mar. 2016

Final Focus SR backgrounds We need to check background rates for various machine designs The large JLEIC flexibility (5-10 GeV for electrons) makes building a single IR beam pipe challenging The 5 GeV e- design has the highest beam current The 10 GeV design has the highest SR photon energies and the largest beam emittance JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Final Focus Sources Generic Final Focus optics The X focusing magnets are outside of the Y focusing magnets For flat beams the magnets do not fight each other Round beam optics have much stronger magnets making them much larger SR sources JLEIC is closer to round JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Beam pipe Surfaces We have chosen 4 Beam pipe surfaces to monitor Upstream beam pipe inside the final focus elements (-3 m to -4 m) Central IP beam pipe mask at (-1 to -2 m) Important for calculating forward scattering Central beam pipe (3 cm radius) (upstream section 0 to -50 cm) Central beam pipe (downstream section +50 cm to 0) JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Baseline Optics JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Option 1 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Option 2 JLEIC Collaboration Meeting Mar. 2016

Beam pipe and beam distribution In order to compare pineapples to pineapples we have kept the beam pipe design constant between optics options For SR monitoring we trace beam particles out to 10  in x and 25  in y with a beam tail distribution Program used is SYNC_BKG. Originally QSRAD created by Al Clark of LBL (~1983). Designed exclusively for FF SR. JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Cases Studied We have looked at 12 different cases: 3 Optics designs Original Option 1 Option 2 2 beam energies 10 GeV 5 GeV 2 emittances Regular (56/11 nm 10 GeV and 14/2.8 nm 5 GeV) Reduced (39/7.7 nm 10 GeV and 9.8/2.0 nm 5 GeV) JLEIC Collaboration Meeting Mar. 2016

Baseline  from Fanglei Lin e- 2.4 m *=(10,2)cm 0.5 m, 16 T/m, good field r = 4 cm, rinner = 5 cm, router = 10 cm 1 m ion spectrometer  0.7 m, 44 T/m, good field r = 2 cm, rinner = 3 cm, router = 7 cm 0.7 m, 45 T/m, good field r = 4 cm, rinner = 5 cm, router = 10 cm Max. x= 4.1 mm *=(10,2)cm x= 2.1 mm x= 3.4 mm from Fanglei Lin JLEIC Collaboration Meeting Mar. 2016

Option 1  from Fanglei Lin e- Beam sizes at FFQ locations are calculated using the baseline design emittances Field gradients are given @ 10 GeV (divided by 2 @ 5 GeV) 2.6 m e- 0.5 m, 29 T/m, good field r = 4 cm, rinner = 5 cm, router = 11 cm 1 m ion spectrometer  0.7 m, 44 T/m, good field r = 3 cm, rinner = 4 cm, router = 8 cm 0.9 m, 42 T/m, good field r = 4.5 cm, rinner = 5.5 cm, router = 11 cm *=(10,2)cm 5 GeV: x,y = (1.6,0.9) mm 10 GeV: x,y = (3.2,1.8) mm 5 GeV: x,y = (2.0,0.8) mm 10 GeV: x,y = (3.9,1.6) mm 5 GeV: x,y = (2.2,0.7) mm 10 GeV: x,y = (4.4,1.4) mm Note that, beam sizes in the above plot are given at locations with maximum horizontal beta functions (i.e. maximum horizontal beam sizes) in the FFQs. One has to calculate the maximum vertical beam sizes if they are desired. from Fanglei Lin JLEIC Collaboration Meeting Mar. 2016

Option 2  from Fanglei Lin e- Beam sizes at FFQ locations are calculated using the baseline design emittances Field gradients are given @ 10 GeV  *=(10,2)cm e- 0.5 m, 28 T/m, good field r = 4.5 cm, rinner = 5.5 cm, router = 12 cm 1 m ion spectrometer 0.7 m, 40 T/m, good field r = 3 cm, rinner = 4 cm, router = 8 cm 0.7 m, 46 T/m, good field r = 5 cm, rinner = 6 cm, router = 11 cm 10 GeV: x,y = (2,2) mm 2.4 m 0.3 m, 14 T/m (permanent), good field r = 2 cm, rinner = 3 cm, router = 5 cm 10 GeV: x,y = (3.1,2.2) mm 10 GeV: x,y = (4.9,1.6) mm 10 GeV: x,y = (4.4,1.7) mm Note that, beam sizes in the above plot are given at locations with maximum horizontal beta functions (i.e. maximum horizontal beam sizes) in the FFQs. One has to calculate the maximum vertical beam sizes if they are desired. from Fanglei Lin JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Reminder JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface a (10 GeV) 10 GeV >10 k >50 k W Bas. High Emit. 8039 3096 <.1 Opt 1 High Emit. 1.01e6 4.14e5 5.5 Opt 2 High Emit. 4.85e6 2.09e6 27.9 Bas. Red. Emit. 0.0 0.0 0.0 Opt 1 Red. Emit. 0.0 0.0 0.0 Opt 2 Red. Emit. 1.03e6 4.09e5 5.3 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface a (5 GeV) 5 GeV >10 k >50 k W Bas. High Emit. 0.0 0.0 0.0 Opt 1 High Emit. 0.0 0.0 0.0 Opt 2 High Emit. 3.56e6 1.28e5 9.3 Bas. Red. Emit. 0.0 0.0 0.0 Opt 1 Red. Emit. 0.0 0.0 0.0 Opt 2 Red. Emit. 7.15e5 2.23e4 1.7 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface b (10 GeV) 10 GeV >10 k >50 k W Bas. High Emit. 3.68e7 8.74e6 134 Opt 1 High Emit. 1.48e8 1.95e7 437 Opt 2 High Emit. 2.62e8 3.32e7 762 Bas. Red. Emit. 2.24e7 5.66e6 82.7 Opt 1 Red. Emit. 6.92e7 1.01e7 210 Opt 2 Red. Emit. 1.30e8 1.62e7 379 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface b (5 GeV) 5 GeV >10 k >50 k W Bas. High Emit. 1.04e6 815 5.1 Opt 1 High Emit. 1.52e6 1271 8.2 Opt 2 High Emit. 1.79e7 7.24e4 142 Bas. Red. Emit. 4.32e5 127 2.5 Opt 1 Red. Emit. 7.03e5 259 4.4 Opt 2 Red. Emit. 9.80e6 4.06e4 70 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface c (10 GeV) 10 GeV >10 k >50 k W Bas. High Emit. 3.98e4 1.34e4 0.18 Opt 1 High Emit. 1.89e4 6556 0.09 Opt 2 High Emit. 4455 1772 0.03 Bas. Red. Emit. 1.41e4 4498 0.05 Opt 1 Red. Emit. 0.0 0.0 0.0 Opt 2 Red. Emit. 651 262 <0.01 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface c (5 GeV) 5 GeV >10 k >50 k W Bas. High Emit. 0.0 0.0 0.0 Opt 1 High Emit. 0.0 0.0 0.0 Opt 2 High Emit. 1735 48.7 <0.01 Bas. Red. Emit. 0.0 0.0 0.0 Opt 1 Red. Emit. 0.0 0.0 0.0 Opt 2 Red. Emit. 56 1.0 <0.01 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface d (10 GeV) 10 GeV >10 k >50 k W Bas. High Emit. 3.16e5 8.99e4 1.23 Opt 1 High Emit. 3.12e5 8.45e4 1.18 Opt 2 High Emit. 1.40e5 4.69e4 0.63 Bas. Red. Emit. 1.89e5 5.12e4 0.62 Opt 1 Red. Emit. 198 0.03 <0.01 Opt 2 Red. Emit. 6.25e4 1.95e4 0.26 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Surface d (5 GeV) 5 GeV >10 k >50 k W Bas. High Emit. 1997 1.3 <0.01 Opt 1 High Emit. 1765 0.7 <0.01 Opt 2 High Emit. 2.30e5 5869 0.63 Bas. Red. Emit. 1258 0.65 <0.01 Opt 1 Red. Emit. 198 0.034 <0.01 Opt 2 Red. Emit. 5.80e4 994 0.17 JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Some results Difficult to get an IR beam pipe much smaller than a 3cm radius. Calculated the number of photons that penetrate the beam pipe For a 1mm thick pipe of Be and 10 and 25 um of Au inner layer Estimated incident angle of photons is 14 mrad Then about 2% of the incident photons penetrate Need to know how long the central pipe needs to be (assuming right now ±50 cm) Shorter pipes are easier to shield JLEIC Collaboration Meeting Mar. 2016

Photon Energy plot (10 GeV) Surface d 10 um Au 3.16105 4.49103 JLEIC Collaboration Meeting Mar. 2016

Photon Energy plot (10 GeV) Surface d 25 um Au 3.16105 2.74103 JLEIC Collaboration Meeting Mar. 2016

Photon Energy plot (5 GeV) Surface d 10 um Au 1997 6.5 JLEIC Collaboration Meeting Mar. 2016

Total SR power and photons from upstream FF quads (10 GeV) Photons Power(W) Baseline High Emit. 1.211010 3658 Option 1 High Emit. 1.531010 4834 Option 2 High Emit. 1.541010 5356 Baseline Red. Emit. 1.031010 2648 Option 1 Red. Emit. 1.281010 3384 Option 2 Red. Emit. 1.291010 3749 JLEIC Collaboration Meeting Mar. 2016

Total SR power and photons from upstream FF quads (5 GeV) Photons Power(W) Baseline High Emit. 1.301010 251 Option 1 High Emit. 1.621010 320 Option 2 High Emit. 3.301010 1337 Baseline Red. Emit. 1.091010 176 Option 1 Red. Emit. 1.351010 224 Option 2 Red. Emit. 2.761010 936 JLEIC Collaboration Meeting Mar. 2016

Surface d Option 1 (10 GeV) Smaller IP beam pipe 10 GeV >10 k >50 k W Opt 1 HE 3 cm 3.12e5 8.45e4 1.18 Opt 1 HE 2.5 cm 2.22e6 1.15e5 7.05 Opt 1 HE 2 cm 1.22e7 1.61e6 34.9 Photon rates go up almost x10 for each 5mm decrease in radius JLEIC Collaboration Meeting Mar. 2016

Where does it come from? For surface d JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Summary Based on this initial study of SR backgrounds Option 1 looks to be the most promising Reduced beam emittance is a big winner Masking can probably be further optimized 5 GeV beam is much easier Emittances are smaller Photon critical energies are lower JLEIC Collaboration Meeting Mar. 2016

JLEIC Collaboration Meeting Mar. 2016 Conclusions SR for the JLEIC IR looks controllable but needs further study Especially more information from the detector group about what they need at very low angles Also need feedback from detector people as to what are acceptable background rates for the inner trackers How many photons/collision going into the inner detectors are OK before occupancy or radiation damage occurs There is always more to do… JLEIC Collaboration Meeting Mar. 2016