Fragmentation of 132Sn

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Fragmentation of 132Sn
238U E950 Mev/u
Fission Fragments
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Requirements of SC1
Time Resolution for ToF 1
?B?/ B? 3 10-4 ?A/A 4.5 10-3 L 18 m
?ToF150 ps
Size of Scintillator
GICO matrix 1st order (only X Y)
X Y
X -0.508 0
A 0 0
Y 0 -5.407
B 0 -0.152
P 2.149 0
?x ?y 1mm ?p4 ?a ?b 40 mrad
x 8.09 cm y 6.58 cm
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MOCADI Simulation
TA
S1
5 cm
8 cm
S2
132Sn _at_ 1Gev/u ?x ?y 1mm ?p4 ?a40 mrad
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Requirements of SC1 (II)
Count rate at S2
Beam intensity 108 ions/s Target Pb Thickness
1.5 g/cm2
132Sn 103 ions/s Others2.6 104 ions/s
The very high counting rate at S1 requires a high
counting rate photomultiplier tube
HAMAMATSU H2431-50MOD assembly
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H2431-50MOD

• Very fast response (Tr0.7 ns)
• Booster base --gt higher rates allowed

Insterstage voltage of last dynodes supplied by
independent HV power supplies (PS). Even if the
output current of PMT is increased, no voltage
losses. (Each HV PS keeps a constant voltage)
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H2431-50MOD (II)
R2083 tube
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Improved VME Data Acquisition (DAQ) for the FRS

• VME Data Acquisition (Single Event)
• VME Data Acquisition (Multi event)
• Implementation of Multi Event DAQ
• Present Status
• Next steps

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Fragmentation of 132Sn
238U E950 Mev/u
Expected rate 2.6 104 ions/s

• Rate at S2 is limited by the DAQ,
• (1 kHz presently)
• With Multi Event DAQ ?3-4 kHz
• Degrader at S1 for reducing rate

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Single Event DAQ

• Present DAQ system _at_ FRS
• Each Event trigger corresponds to a readout
  trigger.
• VME modules are read sequentially in single cycle
  mode. (Address is sent with each data transfer)
• Rate limited 1kHz

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Multi event DAQ

• Collect up to 32 event in the multi-event buffer
  of CAEN modules (drawback only valid for these
  modules).
• They are read in a VME block transfer (faster).
  Readout is performed after 32 events or end of
  spill
• Each MBS event contains up to 32 event triggers

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Implementation Multi event DAQ

• Three Different working fields
• VME block readout
• Setting up new trigger electronics
• New analysis routines

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Present Status

• Readout function already written and working for
  2 CAEN V775 TDC modules (col. C. Nociforo, N.
  Kurz)
• Trigger Scheme reproduced in a test rack in the
  Electronics Lab of FRS
• Preliminary GO4 unpacking routines ready

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Next Steps

• Extend the Readout function to all modules of FRS
  VME crates
• Implement the new trigger electronics
• Continue with the GO4 routines for analysis.