Analog readout of the RPCs in the ARGOYBJ experiment .

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Analog read-out of the RPCs in the ARGO-YBJ
experiment .
Astrophysical Radiation Ground-based Observatory a
t YangBaJing
Michele Iacovacci, VIIth Workshop on
Resistive Plate Chambers and Related
Detectors, Clermont-Ferrand, October 20-22, 2003
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ARGO-YBJ Collaboration Institutes
Spokesman Y.H.Tan
Spokesman B.DEttorre Piazzoli

• INFN and Dipartimento di Fisica dellUniversita,
  Lecce
• INFN and Dipartimento di Fisica
  dellUniversita, Napoli
• INFN and Dipartimento di Fisica dellUniversita
  Roma Tre, Roma
• INFN and Dipartimento di Fisica dellUnivesita
  Tor Vergata, Roma
• Istituto di Cosmogeofisica del CNR and INFN,
  Sezione di Torino
• Istituto di Fisica Cosmica IFCAI/CNR, Palermo and
  INFN,
• Sezione di Catania

• IHEP,Beijing
• Shandong University, Jinan
• South West Jiaotong University, Chengdu
• Tibet University, Lhasa
• Yunnan University, Kunming
• Zhenghou University, Henan

50 Physicists
50 Physicists
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ARGO-YBJ Experiment
A Ground-based g-astronomy experiment
Main goal Observation of galactic and
extragalactic g radiation in the energy range
300 GeV ? 10 TeV.
A new generation EAS array
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The ARGO Detector
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Site Location
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ARGO-YBJ
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High Altitude Cosmic Ray Laboratory _at_
YangBaJing (Site Coordinates longitude 90 31
50 E, latitude 30 06 38 N)
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yak
ARGO-YBJ
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ARGO Layout
SPACE PIXEL 124800 (147840)
111 x 99 m2
78 x 75 m2
6 x 62 cm2
5.7 x 7.7 m2
60 x 62 cm2
1.25 x 2.8 m2
TIME PIXEL 15600 (18480)
1 CLUSTER 12 RPCs 44 m2
CARPET 130 CLUSTER 5850 m2
COVERED AREA 154 CLUSTER 10989 m2
1 RPCs 3.5 m2
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Space view of an event with 512 hits detected by
16 Clusters (pixel Pad)
Projected space-time view of the same event
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View of an event with 800 hits detected by 16
Clusters
Time (ns)
Pad number
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A shower giving 444 hits on 16 Clusters. The
shower core is well contained into the detector
area.
Time (ns)
Pad number
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Inside
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Experimental Hall
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Why the charge read-out
A simulation has been carried out by means of the
CORSIKA/QGSjet code in order to study the
dependence on the energy of the number of fired
strips for quasi-vertical ( lt15) showers with
core in a fiducial area (Af) of 260 m 2 in the
center of the carpet.The average strip size (Nx)
is compared to the total size and to the size
sampled by the central carpet (truncated size)
for proton induced showers. It comes out the
digital response of the detector cannot be used
to study the primary spectrum at energies above a
few hundreds TeV.
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Signal from the Big Pad
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ChargeMeter Circuit
Signal
t 300 ns
Trigger
The Big Pad is read out via a unity gain
Peak-and-Hold (PH) circuit, specifically designed
to fulfill the detector requirements The PH
circuit is able to track the Big Pad signals
starting from a settable threshold (few mV).
When this threshold is exceeded, the PH
generates a timing gate of 2 ms and in this
window it keeps the maximum value of the input
signal. The presence of a trigger during this
hold-and-update phase validates the event and the
PH output level is digitized by a 12-bit ADC
with a conversion time of 135 ns. If in the
elapsed timing gate no trigger is produced, the
PH restarts the operations and clears its output.
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INPUT
1 - channel prototype
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(No Transcript)
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Charge read-out in ARGO-YBJ
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Dt 1.5-2.5 ms
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Study of the m.i.p. signal

• Gas Mixtures
• 15 Ar 10 IsoB 75 C2H2F4
• 15 Ar 20 IsoB 65 C2H2F4 .3SF6
• 15 Ar 30 IsoB 55 C2H2F4 .3SF6

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15/10/75
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15/10/75 Oscilloscope Signals
Oscilloscope
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15/20/65 .3 SF6
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Amplitude Distribution _at_ 15/30/55 .3SF6
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15/30/55 .3 SF6
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Comparison Efficiency
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Comparison Charge
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Charge Angular dependence
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Conclusions

• The Charge Read-out project is going on. The
  circuit which has been realized will allow to
  measure particle density greater then 1000/m2.
• A few gas mixtures have been tested. We found
  that the peak structure of the charge
  distribution gets less and less evident with SF6.
  
• The SF6 reduces the mean amplitude notably (by
  a factor gt 5) .
• The efficiency knee moves on by adding SF6.
• The mixtures with SF6 allow to operate with a
  reduced angle dependence.