24-28 May, 2010 S. Mastroianni - 17th Real-Time Conference, Lisboa, Portugal

•ARGO-YBJ is a cosmic ray air shower detector based on a single layer of RPC covering a total instrumented area of ~ 10,000 m2

High altitude site (YBJ, 4300 m a.s.l.)Layer of RPC covering 5800 m2 ( 92% active surface) with 0.5 cm lead converter + sampling guard ring Central Carpet: 130 Clusters, 1560 RPCs, 124800 Strips

•High space-time resolution (time1 ns; space (strip) 6.5 ×62 cm2)•In stable data taking since Nov. 2007 (d.c. > 90%)•Low Multiplicity trigger with 20 fired pads on the central carpet

Trigger rate ~ 3.7 kHz, dead time ~ 4%, data acq. rate 3 MB/s;•Aims:

cosmic-ray physics (~1 TeV a few PeV)VHE γ-astronomy (above ~300 GeV)

S. Mastroianni INFN sez. di Napoli On behalf of the ARGO-YBJ Collaboration

The RPC charge Read-Out system of the ARGO-YBJ detector

To investigate the PeV energy region, we must have the ability to detect air showers with a secondary charged particles density of

~ 103 particles/m2

the charge read out has been implemented by instrumenting each RPC with two Big Pads (BP 140125 cm2 ) 1 Cluster = 24 BPs

~1.7103particles/BigPad

Sat

ura

tion

of

digi

tal r

ead

out BigPad dens

1000/m2

STRIP dens

22/m2

Det

ecto

r

Longitude 90° 31’ 50” EastLatitude 30° 06’ 38” North

4300 m above the sea level90 Km North from Lhasa (Tibet)

Collaboration Institutes: Chinese Academy of Science (CAS) Istituto Nazionale di Fisica Nucleare (INFN)

24-28 May, 2010 S. Mastroianni - 17th Real-Time Conference, Lisboa, Portugal

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Rise time ~ 20-30 ns, Amplitude mV tens of Volts; duration ~ 10 μs Filter/Linear Amplifier/ Shaper/Peak&Hold/12-bit ADC/Buffer

Conversion enabled by a local density trigger (16, 32, 64 hit particles for Cluster)

The data read-out is managed by the Control Module that provides an interface with the Trigger and the main DAQ systems

…. and each Control Module

is connected in a daisy-chain network (link of 1Mbit/s) for control and monitoring purposes

handles the calibration (~ 4000 BPs on a very huge surface with an extreme variation of the environmental parameters) by means of a 12-bit DAC on each CM board.

Typical m.i.p. signals in the Big Pad with the detector operated at 9.5 kV with a gas

mixture made of 15% Ar, 10% I-C4H10 and

75% R143a.

Amplitude

mV40 V

Duration: > 10s

Rise Time :

20-30 ns

The charge read-out system is based on a custom crate (MINICRATE)- two independent sections each one manages 24 BP signals form Cluster module

3 Charge Meter cards 1 Control Module for the data read-out

The Charge Meter system

Input signal adapted to 50 Ω with a coaxial cable (12.5 m, attenuation of ~ 5%)a voltage filter cuts out spikes greater than 40 V linear amplifier with variable gain (VGA: 0.33, 0.66, 1.3, 2.5, 5, 10, 20 and 40 V)constant fraction amplifier cuts the long tail of the input signal in order to realize the coincidences on the same shower (in about 500 ns); Peak&Hold with a tilt time of 4mV/μs, for 2 μs. ADC digitalization within 1.4 μs data collection managed via a custom bus protocol operated on the backplane lines.

24-28 May, 2010 S. Mastroianni - 17th Real-Time Conference, Lisboa, Portugal

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The central carpet (130 Clusters) has been instrumented with all the charge read-out electronics at the YangBaJing Laboratory since November 2009.The gain of the electronics was set at he moment in order to operate in the amplitude range 0-300 mV of the input signals allowing the overlap between digital and analog readout which is another way to calibrate the analog system. Three local trigger configurations were successfully tested (16, 32 and 64 particles on at least one Cluster). In about six months of data taking, a few ten million showers have been reconstructed with the analog system.

The Event selection

Test results and data recorded by the charge read-out Test results and data recorded by the charge read-out system confirm the design expectations, thus the ARGO-YBJ system confirm the design expectations, thus the ARGO-YBJ

capability to operate at a very high particle density capability to operate at a very high particle density (> 10(> 1033 particles/m particles/m22).).

~ Contained events

Central carpet saturated

~ localized event

24-28 May, 2010 S. Mastroianni - 17th Real-Time Conference, Lisboa, Portugal

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Thank you for Thank you for your attention!your attention!

POSTER –PDAQ 26POSTER –PDAQ 26