IX th International Conference on Hypernuclear and Strange Particle Physics (HYP06) - Mainz, Germany, 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 e – electroproduction of Hypernuclei Rich upgrade for higher momenta and faster acquisition Conclusions Francesco Cusanno, INFN Gruppo Sanità, Sezione di Roma

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

O ptimization of Optics: the Database

Four Optical Elements (QQDQ) Design Resolution FWHM momentum resolution Previously best obtained 2.5  FWHM momentum resolution Multiple Coulomb Scattering is the reason for the difference Typical HRS System Both Spectrometers Have Demonstrated ~ 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

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

K AON Id Requirements – Physics case ProcessRates signal(e,e’K) bound state – accidentals (e,e’)(e,  ) (e,e’)(e,p) (e,e’)(e,k) 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

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

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 20sin   ELN i icep  Francesco Cusanno – HYP 06 – Mainz, Germany, 10 – 14 October 2006

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

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

J LAB Hall A RICH: the evaporation system Photocathode 110 cm 120 cm 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

R ICH front end electronics and D AQ system  3 PhotoCathode each divided in 80*48=3840 pads  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

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

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: 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

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

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 ~ 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

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

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. =   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

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

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

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

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

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

C onclusions : Septum Magnets has been successfully operated, High Resolution Spectrometers with Septum Magnets provide momentum resolution of 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