Parasitic Run Physics Simulations HPS Collaboration Meeting October 17 – 19, 2011 Parasitic Run Physics Simulations Takashi Maruyama SLAC

Introduction The goal of the parasitic run is to commission the HPS apparatus and check the performance. Physics simulation is used to estimate the rates in Ecal and Tracker. Ecal One cluster trigger EM trigger MIP trigger Two cluster trigger  e+e- Energy calibration 0 High rate trigger and DAQ Tracker Tracking performance Pattern recognition Tracking efficiency Momentum resolution Different B field Vertex resolution  e+e- , 0/K0+- Mass resolution K0, ,  decays Tracker alignment No field data

Rate estimates in the parasitic run Beam 107 ’s/sec with 1/k (kmin=0.20Ebeam, kmax=0.95Ebeam , Ebeam=4.4 GeV ) Use 1.4107 ’s/sec (kmin = 0.5 GeV, kmax = 4.4 GeV) Target 0.1% X0 Gold at z= -60 cm Detector Dead zone is 10 mrad Ecal 10 mr y= 20 mm Target y = 7mm 8 9 11 13 3 mm (uncollimated) 1.5 mm (collimated) Z = -60 cm Z= 137 cm

Simulation +Au interactions are simulated. Acceptance EM interaction Geant 4 and EGS5 Hadronic interaction Geant 4 and FLUKA Cross sections are not well known. Use measured p cross sections and scale them to estimate Au cross sections. Large uncertainties. Acceptance Particles that came out of the target are tracked in the PS field. Acceptance is B field dependent. We want 5 kG, the test run field. Geometrical acceptance is calculated. 10 mrad dead zone For charged hadrons, FLUKA generated particles are used. 0 and K0+- decays are simulated. 2.5 kG 5.0 kG 7.5 kG Pmin (GeV) 0.25 0.5 0.75

EM interactions pair  50 b, 14 kHz compton 100 mb, 28 Hz Pairs polar angle  me/E Not many pairs reaching Ecal at |Y| > 2 cm. compton 100 mb, 28 Hz  e+e- at Ecal Y (cm) X (cm)

Pairs at large angles Geant4 and EGS5 are in good agreement for pair production rate. However, EGS5 predicts more pairs at large angles. This is due to an exp-based angular distribution ( exp(-/0)) used in Geant4. Only e+ or e- reaches Ecal at |Y| > 2 cm. The double rate is 1 Hz. y (e+) y (e-)

Hadron photo-production A dependence J. Ballam et al, Phys. Rev. D5, 545 (1972)  +/-   100 b 1/A d/d A Assume (A)A(p) p  p  0 H. Van Pee et al, 0704.1776v1 [nucl-ex]   100 b

Hadron photo-production  K+/K-/K0   A. Salam et al, PRC 74, 044004 (2006) E. Anciant et al, PRL 85, 4682 (2000)   0.5 b   1.5 b

Rates  (A) Total rate Single Rate in Ecal Single Rate in Ecal/Tracker Double rate in Ecal Double rate in Ecal/Tracker e+e- 50 b 14 kHz 39 Hz 24 Hz 1.0 Hz 0.6 Hz e- 100 mb 28 Hz 4.6 Hz 0.9 Hz - A +x 20 mb 5.6 Hz 0.2 Hz 0.09 Hz * A0 +x, 0 4 Hz 0.1 Hz AK +x 300 b 0.08 Hz AK0 +x, K0+- A+x, K+K- 100 b 0.03 Hz * Test run tracker/Ecal does not have an acceptance at M > 250 MeV.

Summary The Ecal single rate is 50 Hz, dominated by pairs. The Ecal double rate is 2 Hz. The tracker rate is 1/2 Ecal rate. To test high rate Ecal trigger and DAQ, we need to increase the rate by using higher beam current, thicker converter and lowering/turning-off magnetic field. There are enough 0 for Ecal calibration. Although K0/ decays would be useful for vertexing and mass calibration, the test run apparatus does not have an acceptance at M > 250 MeV.

K0 +- Target Tracker Ecal