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IXth 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
Jefferson LAB Site Location and the CEBAF facility
Hall A
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Optimization of Optics: the Database
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 δ Resolution
Old D.B.
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
New D.B.
Performances of New Setup and Database
Hadron Identification through Aerogel
AERO1 n=1.015
AERO2 n=1.055
p
k
KAONS = AERO1 • AERO2
p k
All events
ph = 1.7 : 2.5 GeV/c
Pions = AERO1 • AERO2
Protons = AERO1 • AERO2
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
KAON Id Requirements – Physics case
Process Rates
signal (e,e’K) bound state
10-4 – 10-2
accidentals (e,e’)(e,)
(e,e’)(e,p)(e,e’)(e,k)
1001000.1
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. BackgroundHypernuclear spectroscopy
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Freon Radiator: 1800x400x15 mm3 single box with quartzwindows 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 photocathodesThree Photocathodes :
403x640 mm2 each, divided in 8.4 x 8 mm2 size pads evaporated with a 300 nm CsI layer
JLAB Hall A RICH layout – similar to ALICE HMPID RICH
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
JLAB Hall A RICH MonteCarlo Simulations
, K Separated by , K Separated by
– K = 30 mrad
mrC
4.4
, K Separated by , K Separated by 6.8 6.8
Separation powerSeparation power
c n12
N. of detected N. of detected photoelectronsphotoelectrons
20sin370 2.. ELN
iicep
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
JLAB Hall A RICH: some components
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Photocathode positioning in the glove box
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
JLAB Hall A RICH: the evaporation system
Photocathode
110 cm
120
cm
10-6 mbar vacuum2 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
MeasurementSystem
details in : F.Cusanno et al.NIM A502(2003)251
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
RICH front end electronics and DAQ 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 – HYP06 – Mainz, Germany, 10 – 14 October 2006
JLAB Hall A RICH Event Display during data taking
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
JLAB Hall A RICH OPERATING conditions
Gas: Pure Methane (Minimize Photon Feedback, High Q.E.)
High Voltage: ~ 2100 Volts for a gain of 8x104
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 – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich Performances – key parameters :
mrad c
5
Angular resolution :Npe /p ratio :
66.01
122
22
n
n
N
N P
clus
Pclus
Npe for and P Cherenkov angle reconstruction
Cherenkov average angle (rad)Nclusters
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Aero Selected
Aero Selected P
Aero Selected K (!)
Aero Selected Kon a large sample of filtered data
Separation power
cK 6
mrad c
5Angular resolution
/K population ratio
100
Kaon selection:cK 3
This would accept ~ 10-4 pions x /K ratio
1/100 pion contamination
…. But NON GAUSSIAN TAILS GIVE AN
IMPORTANT CONTRIBUTION !
Rich Performances – PID :
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich – PID – Kaon selection results :
P
K
Time of coincidence for Aerogel Selected Kaons w/o and w/ rich :
AERO K AERO K && RICH K
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich – PID – Pion rejection factor :
Time of coincidence for Aerogel Selected Pions: effect of Rich Kaon selection
N.Evts in the peakBackgnd subtr. =
64656
N.Evts in the peakBackgnd subtr. =
63
Pion rejection~ 1000
AERO && RICH KAERO
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich 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 studiedfor high rates running
However running at reduced gain with moderately goodperformance seems to be feasable
• /K separation for p>2.5 GeV/c
Doable “just” replacing the radiator C5F12 in liquid phase (<24°C)
• DAQ rate bottleneck (~1kHz) can be overcome replacing front-end
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich /K separation for p > 2.5 GeV/c
Radiator C6F14 n=1.29 Ch ~ 5mr
Radiator C5F12 n=1.24 Ch ~ 5mr
4 separation at ~ 2.5 GeV/c 4 separation at ~ 3.0 GeV/c
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich /K separation Vs. proximity Gap lengthwith C5F12 (n=1.24) radiator - MonteCarlo Simulations
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich /K separation with C5F12 (n=1.24) radiator (14 cm proximity gap)
>20 separation at ~ 2 GeV/c ~ 4 separation at 3.0 GeV/c
MonteCarlo Simulations
Francesco Cusanno – HYP06 – Mainz, Germany, 10 – 14 October 2006
Rich electronics upgrade :
VMEto
Local BusInterface
SegmentController
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 BOARDSEGMENT
GA
SS
IPL
EX
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 – HYP06 – Mainz, Germany, 10 – 14 October 2006
Conclusions:
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 – HYP06 – Mainz, Germany, 10 – 14 October 2006