W. Morse GamCal1 GamCal: a Beam-strahlung Gamma Detector for Beam Diagnostics William M. Morse Brookhaven National Lab

W. Morse GamCal2 GamCal Detector W. Morse (BNL): Coordinator M. Ohlerich et al. (Zeuthen): beam- strahlung simulations B. Parker (BNL): Machine interface issues M. Zeller, G. Atoian, V. Issakov, A. Poblaguev (Yale): GamCal detector design Y. Nosochkov (SLAC): Extraction line issues

W. Morse GamCal3 RDR: Luminosity Feedback Detectors BeamCal and GamCal

W. Morse GamCal4 Beam-strahlung Gammas F = e(E + c  B) E = 0, B max  1KT P   2% P e  0.3MW N   1.5N e  3  /BX

W. Morse GamCal5 Beam-strahlung Pairs Bethe-Heitler:  e → e e + e -  BH  38 mb  1GeV Landau-Lifshitz: ee → ee e + e -  LL  19 mb  0.15GeV

W. Morse GamCal6 Beam-strahlung Pairs  0.1m low Z

W. Morse GamCal7 Bethe-Heitler Pairs  e → e e + e - For left and right detectors separately: N + /  x  y and N - /  x  y.

W. Morse GamCal8 Vertical Offset M.Ohlerich complementary information from 1.total photon energy vs offset_y 2.BeamCal pair energy vs offset_y ratio of E_pairs/E_gam vs offset_y is proportional to the luminosity similar behaviour for angle_y, waist_y … see also: EUROTeV-Memo

W. Morse GamCal9 GamCal and BeamCal Measuring the beam-strahlung pairs and gammas provides robust complementary information Ratio of pairs to gammas is largely proportional to the instantaneous luminosity

W. Morse GamCal10 BeamCal.003 <  <.02 rad  3.5m from IR Pairs curl in the magnetic field Measure the  10 4 beam-strahlung e + e - pairs/BX for beam diagnostics The distribution of the pairs on the BeamCal contains rich information on the beam parameters of the collision (beam sizes, emittances, etc.)

W. Morse GamCal11 GamCal Detector  180m from IR  X 0 to convert beam-strahlung gammas into e + e - pairs Converter could be gas jet or a thin solid converter Dipole magnet with P T kick 0.25 GeV/c separates the pairs from beam electrons Calorimeters outside vacuum after magnet measure the 1-10 GeV positrons

W. Morse GamCal12 Statistical Error for BX

W. Morse GamCal13 Start-up?

W. Morse GamCal14 Beam-strahlung  Z  e + e - Z

W. Morse GamCal15 GamCal Backgrounds from Beam Electrons ProcessBackground/signal Bremsstrahlung<1% Delta rays<1% Landau-Lifshitz  6%  production <0.1%

W. Morse GamCal16 Ratio of  Z  eeZ vs. eZ  eZee

W. Morse GamCal17

W. Morse GamCal18 Yale IBS Design

W. Morse GamCal19 Beam Diagnostics Detectors Conclusions BeamCal and GamCal provide robust complimentary information. GamCal backgrounds look OK – needs simulations. Can measure, and then subtract, the GamCal background by accelerating only one beam. Ratio of the beamstrahlung pairs (BeamCal) to gammas (GamCal) is largely proportional to the instantaneous luminosity. There is much rich information from pair distributions on BeamCal and IBS camera, which we are studying.

W. Morse GamCal20 Extra Slides

W. Morse GamCal21 Feed-back with Luminosity Detectors

W. Morse GamCal22 BNL Magnet Division Position Stability

W. Morse GamCal23 Achieving the ILC Luminosity Will Be a Challenge Bunch P - (t) {N,  x,  y,  z,  xy,  x,  y } Bunch P + (t) {N,  x,  y,  z,  xy,  x,  y } Instantaneous Luminosity: x y

W. Morse GamCal24 IBS Camera

W. Morse GamCal25 IBS Camera

W. Morse GamCal26 1  21  2 + - y z

W. Morse GamCal27 Perfect Collisions

W. Morse GamCal28 Bunch width

W. Morse GamCal29 Bunch Width

W. Morse GamCal30 GamCal Backgrounds

W. Morse GamCal31  Z  eeZ vs. eZ  eZee Electron carries virtual gammas Landau Lifshitz conversion of virtual gammas

W. Morse GamCal32  Production Compared to ee  p  eep   10 mb  p   N   0.5 mb on peak of Δ resonance  p   N   0.1 mb E > 4GeV ep  e  N   mb Thus ep  e  N is negligible