A Polarimetry concept for the EDM experiment at COSY Paul Maanen JEDI Collaboration Physics Institute III B, RWTH Aachen University DPG Frühjahrstagung March 27, 2015
Outline Introduction Detector concept Simulation studies Summary & Outlook 2/15 Paul Maanen
Design goals for an EDM polarimeter EDM search in storage rings: Let Electric Dipole Moment (EDM) interact with fields, wait for polarization change. Current candidate method for EDM search implicates a linear buildup of polarization with time at P = O( 6 /00s) Design goals for polarimeter: Large FoM Minimal influence on beam High sensitivity to systematic effects Good long term stability and reproducibility 3/15 Paul Maanen
Nuclear scattering polarimetry Nuclear scattering cross section for scattering of polarized particles: (, )= 0 ( ) 1 + P y A y ( ) cos( ) Measure left-right asymmetries in cross section: P y = 1 A y L R L+R May need to also include up, down to account for tensor polarization. Currently using dc scattering at 270 MeV 4/15 Paul Maanen
Target choice Analyzing Power 2 FOM = σ A y A y 1 0.8 270 MeV FOM 2 270 MeV 0.6 0.4 200 MeV 0.2 0 200 MeV 0.2 0 5 15 20 25 30 35 Θ [degree] 0 5 15 20 25 30 35 Θ [degree] Cross-section dσ /dω [mb/sr] 3 2 270 MeV 1 200 MeV 1 2 0 5 15 20 25 30 35 Θ [degree] Carbon was chosen as working choice. Large analysing power, high elastic cross section Most other target also favor forward region. 5/15 Paul Maanen
Target concept 6/15 Paul Maanen
Detector concept Fast HCAL Target chamber PL Sci PMT Vacuum pipe COSY beam 7/15 Paul Maanen
ucpu ucpu Readout Concept Crystal PMT SADC FPGA FIFO Struck SIS 3316 16 channel 64MS/ch 250MS/s 4ns per S. SWITCH Pile-Up... Triggerless readout: Use waveform digitizers and read out every on every crossing of beam and target. Use FPGA-based online analysis; could provide data for feedback system. 8/15 Paul Maanen
Candidate Layout First Step 4x12=48 LYSO 4x15=60 BGO Final Version LYSO & BGO 9/15 Paul Maanen
Simulation studies (cont d) elastic [MeV] E k 300 280 260 elastic_theta_ek Entries 24583 Mean x 8.731 Mean y 268.1 RMS x 6.864 RMS y 3.038 2500 2000 240 1500 220 200 00 180 500 160 0 20 30 40 50 60 elsetic [deg] ϑ lab 0 Elastically scattered deuterons retain almost complete beam energy. /15 Paul Maanen
Simulation studies (cont d) elastic [MeV] 160 140 120 ϑ proton (break-up) lab proton_theta_ek Entries 3859051 Mean x 47.73 Mean y 57.64 RMS x 35.14 RMS y 48.72 elastic [MeV] 160 140 120 ϑ lab neutron neutron_theta_ek Entries 3757577 Mean x 45.48 Mean y 58.49 RMS x 34.05 RMS y 48.16 E k E k 0 0 80 80 60 60 40 40 20 20 0 0 20 40 60 80 0 120 140 160 180 ϑ (d C p X) inelsetic [deg] lab 0 0 20 40 60 80 0 120 140 160 180 ϑ (d C n X) inelsetic [deg] lab elastic [MeV] E k 160 140 120 deuteron ϑ lab deuteron_theta_ek Entries 360934 Mean x 72.5 Mean y.91 RMS x 36.68 RMS y 9.606 num. of events 7 6 5 number of secondaries (inelastic) num_secondaries Entries 1974048 Mean 6.06 RMS 1.392 0 4 80 60 3 40 2 20 0 0 20 40 60 80 0 120 140 160 180 ϑ (d C d X) inelsetic [deg] lab 1 0 2 4 6 8 12 14 16 18 20 num. of secondaries Break-up has almost no analyzing power, so discard it. Protons and neutrons from break-up are energetically well separated. =)Complete stop of particles provides good signal separation. Inelastic reactions carry some analysing power, so maybe keep these. 11/15 Paul Maanen
Simulation studies (cont d) deuteron path length in LYSO depth [mm] 70 60 50 40 30 20 σ = 0.1 σ = 0.6 Fully stopped deuterons [%] 95 90 85 80 75 70 65 60 0 150 200 250 300 deuteron kinetic energy [MeV] 55 0 150 200 250 300 deuteron kinetic energy [MeV] 12/15 Paul Maanen
Simulation studies 1cm Plastic Scintillator Tracker C target 3x3xcm LYSO 0.5mm Stainless Steel 13/15 Paul Maanen
Summary & Outlook We have a candidate layout for JEDI polarimeter. Crystals and electronics have been ordered for hardware tests. Will explore gain from tracking capabilities. Work on mechanical setup in progress. By the end of 2015, first prototype test is expected... 14/15 Paul Maanen
Thank you for your attention Any questions?