1. IX th International Conference on Hypernuclear and Strange Particle Physics (HYP06) - Mainz, Germany, 10 -14 October, 2006 Hall A Experimental setup modification The Septum Magnets Optics of new High Resolution Spectrometer setup The Jlab Hall A RICH Layout Electronics Read Out and DAQ Performance and results during experiment e94-107 – electroproduction of Hypernuclei Rich upgrade for higher momenta and faster acquisition Conclusions Francesco Cusanno, INFN Gruppo Sanità, Sezione di Roma

2. J efferson L AB Site Location and the CEBAF facility Hall A Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

3. O ptimization of Optics: the Database

4. Four Optical Elements (QQDQ) Design Resolution 10 -4 FWHM momentum resolution Previously best obtained 2.5  10 -4 FWHM momentum resolution Multiple Coulomb Scattering is the reason for the difference Typical HRS System Both Spectrometers Have Demonstrated ~ 10 -4 FWHM  Resolution Old D.B. Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006 New D.B. P erformances of New Setup and Database

5. H adron Identification through Aerogel AERO1 n=1.015 AERO2 n=1.055 p k  KAONS = AERO1 AERO2 p k All events p h = 1.7 : 2.5 GeV/c  Pions = AERO1 AERO2 Protons = AERO1 AERO2 Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

6. K AON Id Requirements – Physics case ProcessRates signal(e,e’K) bound state 10 -4 – 10- 2 accidentals (e,e’)(e,  ) (e,e’)(e,p) (e,e’)(e,k) 100 0.1 Very forward angle  high background of  and p  TOF and 2 threshold Cherenkov aerogel are NOT sufficient for unambiguous K identification  RICH DETECTOR Signal Vs. Background Hypernuclear spectroscopy Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

7. Freon Radiator: 1800x400x15 mm 3 single box with quartz windows glued on neoceram housing Grid plane: 100  m positive wires (collects electrons ionized in the gap) Wire chamber : composed by 20  m anode wires plane sandwitched between a cathode plane formed by 100  m wires and the cathode plane formed by the photocathodes Three Photocathodes : 403x640 mm 2 each, divided in 8.4 x 8 mm 2 size pads evaporated with a 300 nm CsI layer J LAB Hall A RICH layout – similar to ALICE HMPID RICH Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

8. J LAB Hall A RICH M onte C arlo Simulations , K Separated by  –  K = 30 mrad , K Separated by  6.8  Separation power N. of detected photoelectrons N. of detected photoelectrons 20sin370 2..   ELN i icep  Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

9. J LAB Hall A RICH: some components Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

10. P hoto c athode positioning in the glove box Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

11. J LAB Hall A RICH: the evaporation system Photocathode 110 cm 120 cm 10 -6 mbar vacuum 2 nm/s CsI deposition at T = 60ºC (CERN experts indications). Vacuum - heating conditions starts 15 – 24 h before evaporation. A post-evaporation heat treatment is done for 12 hours. crucibles Quantum Efficiency Measurement System details in : F.Cusanno et al. NIM A502(2003)251 Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

12. R ICH front end electronics and D AQ system  3 PhotoCathode each divided in 80*48=3840 pads  11520 tot. channels  FEE arranged in 8*6 = 48 rows each each rows handling 240 channels with 15 GASSIPLEX chips (for amplification, holding and multiplexing analogue signals – 16 pads per gassiplex chip)  Readout using CAEN System with CAEN V550 CRAMS and V551 Sequencer  240 pads (15 Gassiplex chips multiplexed signal with zero suppression) per CRAM channel (10 bit FADC) total number of 24 VME modules + 2 VME V551 Sequencer in two VME CRATES.  2 MHz clock speed  no data buffering foreseen in CRAMS - CRAM memory read out for each trigger  Achieved performance :  sampling 120  s (clock) + 10  s = 130  s  VME (60 hits) 54  s  overhead 16  s  200  s deadtime per trigger  Experience : 20 – 25 % deadtime with 1kHz random trigger Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

13. J LAB Hall A RICH Event Display during data taking Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

14. J LAB Hall A RICH OPERATING conditions Gas: Pure Methane (Minimize Photon Feedback, High Q.E.) High Voltage: ~ 2100 Volts for a gain of 8x10 4 Grid Voltage: 250 - 450 Volts Optimal trigger to read-out delay: ~ 400 ns (peaking time of gassiplex response) MIP charge and hit size cluster charge and hit size Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

15. R ich Performances – key parameters : Angular resolution : N pe  /p ratio : N pe for  and P  Cherenkov angle reconstruction Cherenkov average angle (rad) Nclusters Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

16. Aero Selected  Aero Selected P Aero Selected K (!) Aero Selected K on a large sample of filtered data Separation power Angular resolution  /K population ratio Kaon selection: This would accept ~ 10 -4 pions x  /K ratio 1/100 pion contamination …. But NON GAUSSIAN TAILS GIVE AN IMPORTANT CONTRIBUTION ! R ich Performances – PID : Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

17. R ich – PID – Kaon selection results :  P K Time of coincidence for Aerogel Selected Kaons w/o and w/ rich : AERO KAERO K && RICH K Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

18. R ich – PID – Pion rejection factor : Time of coincidence for Aerogel Selected Pions: effect of Rich Kaon selection N.Evts in the peak Backgnd subtr. = 64656   N.Evts in the peak Backgnd subtr. = 63 Pion rejection ~ 1000 AERO  && RICH K AERO  Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

19. R ich Possible improvements : MWPC stability for high rates For single rates ≤ 60 KHz HV=2100 V is OK In the range 60 KHz – 100 KHz HV=2075 V is OK Above 100 KHz HV must be reduced further  MWPC stability (and mechanics) needs to be studied for high rates running However running at reduced gain with moderately good performance seems to be feasable  /K separation for p>2.5 GeV/c Doable “just” replacing the radiator  C 5 F 12 in liquid phase (<24°C) DAQ rate bottleneck (~1kHz) can be overcome replacing front-end Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

20. R ich  /K separation for p > 2.5 GeV/c Radiator C 6 F 14 n=1.29  Ch ~ 5mr Radiator C 5 F 12 n=1.24  Ch ~ 5mr 4  separation at ~ 2.5 GeV/c4  separation at ~ 3.0 GeV/c Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

21. R ich  /K separation Vs. proximity Gap length with C 5 F 12 (n=1.24) radiator - M onte C arlo Simulations Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

22. R ich  /K separation with C 5 F 12 (n=1.24) radiator (14 cm proximity gap) >20  separation at ~ 2 GeV/c ~ 4  separation at 3.0 GeV/c M onte C arlo Simulations Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

23. R ich electronics upgrade : VME to Local Bus Interface Segment Controller fbD[31..0] LOC_ADD[11..0] LOC_CS LOC_R/Wn fbD[27..0] LOC_CS LOC_R/Wn LOC_ADD[3..0] Column Controller (1 to 8) DILO 5 Boards (ADC and DILOGIC) RCB BOARD SEGMENT GASSIPLEX The HMPID ALICE RICH DAQ scheme Front end digitization/ multiplexing On board 48 multiplexed channels (instead of 240) Clock rate up to 10 MHz Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

24. C onclusions : Septum Magnets has been successfully operated, High Resolution Spectrometers with Septum Magnets provide momentum resolution of 10 -4 FWHM The RICH detector has been successfully operated during the hypernuclear experiment at JLab It is a powerful tool for Particle Identification Average Cherenkov angle resolution   ~ 5 mr in good agreement with Monte Carlo simulations Clean kaon identification is possible with a pion rejection ratio ~1000 Upgrade foreseen both to increase the max DAQ rate limit and to increase momentum range for  /K separation Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006