A Polarimetry concept for the EDM experiment at COSY

Transcription

1 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

2 Outline Introduction Detector concept Simulation studies Summary & Outlook 2/15 Paul Maanen

3 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

4 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

5 Target choice Analyzing Power 2 FOM = σ A y A y MeV FOM MeV MeV MeV Θ [degree] Θ [degree] Cross-section dσ /dω [mb/sr] MeV MeV 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

6 Target concept 6/15 Paul Maanen

7 Detector concept Fast HCAL Target chamber PL Sci PMT Vacuum pipe COSY beam 7/15 Paul Maanen

8 ucpu ucpu Readout Concept Crystal PMT SADC FPGA FIFO Struck SIS 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

9 Candidate Layout First Step 4x12=48 LYSO 4x15=60 BGO Final Version LYSO & BGO 9/15 Paul Maanen

10 Simulation studies (cont d) elastic [MeV] E k elastic_theta_ek Entries Mean x Mean y RMS x RMS y elsetic [deg] ϑ lab 0 Elastically scattered deuterons retain almost complete beam energy. /15 Paul Maanen

11 Simulation studies (cont d) elastic [MeV] ϑ proton (break-up) lab proton_theta_ek Entries Mean x Mean y RMS x RMS y elastic [MeV] ϑ lab neutron neutron_theta_ek Entries Mean x Mean y RMS x RMS y E k E k ϑ (d C p X) inelsetic [deg] lab ϑ (d C n X) inelsetic [deg] lab elastic [MeV] E k deuteron ϑ lab deuteron_theta_ek Entries Mean x 72.5 Mean y.91 RMS x RMS y num. of events number of secondaries (inelastic) num_secondaries Entries Mean 6.06 RMS ϑ (d C d X) inelsetic [deg] lab 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

12 Simulation studies (cont d) deuteron path length in LYSO depth [mm] σ = 0.1 σ = 0.6 Fully stopped deuterons [%] deuteron kinetic energy [MeV] deuteron kinetic energy [MeV] 12/15 Paul Maanen

13 Simulation studies 1cm Plastic Scintillator Tracker C target 3x3xcm LYSO 0.5mm Stainless Steel 13/15 Paul Maanen

14 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

15 Thank you for your attention Any questions?