ARGO-YBJ: Italy (INFN) - China (CAS) collaboration

Collaboration:

- Italy: INFN and Dipartimento di Fisica dell'Universita', Lecce; INFN and Dipartimento di Fisica dell'Universita', Napoli; INFN and Dipartimento di Fisica dell'Universita' "Tor Vergata", Roma; INFN and Dipartimento di Fisica dell'Universita' "Roma Tre", Roma; INFN and Istituto di Cosmogeofisica del CNR, Torino; INFN, Sezione di Catania and IFCAI/CNR Palermo; INFN, Sezione di Pavia
- China: IHEP, Beijing; Hong Kong University, Hong Kong; Shandong University, JiNan; South West Jiaotong University, Chengdu; Tibet University, Lhasa; Yunnan University, Kunming; Zhenghou University, Henan

Location: Yangbajing Cosmic Ray Laboratory, 4300 m a.s.l., Tibet (China)

1. Goal of the experiment

The ARGO-YBJ experiment is devoted to the search of cosmic ray sources by means of the observation of galactic and extragalactic neutral and charged radiation in the energy range 100 GeV - 1000 TeV with a detector based on Resistive Plate Chambers (RPC's) covering an area of 6500 m2 and providing a detailed space-time picture of the cosmic ray shower front. The detector is under construction at the Yangbajing Cosmic Ray Laboratory.

More on the experiment...

2.

Activities during the 2001

- Installation of about 80% of the gas distribution network at YBJ.
- Construction of the HV system for 50 clusters.
- Trigger, Trigger Supervisor and DAQ systems put in operation successfully at YBJ.
- Construction of 20 Local Station, 6 of them installated and put in operation at YBJ.
- Construction of more than 600 gas volumes.
- Assembly of 300 RPCs {75%}.
- Transportation to YBJ of 235 RPCs and installation of 16 clusters (192 RPCs) {40%}.
- 6 clusters validated and put in data taking for debugging runs {38%}.

Milestones 2002

Construction of 600 RPCs | 31-12-2002
60 clusters installed by the end of 2002 | 31-12-2002
50 clusters in data taking | 31-12-2002

3. INFN contribution to the experiment in terms of manpower and financial support

Manpower:

47 researchers (27.7 FTE), 2 technologists (1.1 FTE), 7 technicians (3.8 FTE) plus support from the mechanics and electronics workshops of Napoli and Roma-2.

Budget for the Year 2002: 639 kEuro

4. Publications in refereed journal: 4
5. Conference talks: 6

6. Number of undergraduate and doctoral thesis on the experiment:

- n. 7 Ph.D.;
- n. 4 Laurea diplomas.

7. Leadership roles and primary responsibilities in the experiment

- Spokesperson (italian side) B. D'Ettorre Piazzoli [Napoli University]
- Main commitments

> Lecce: Local Station electronics and trigger.

> Napoli: DAQ, gas distribution system, analog read-out, trigger.

> Roma-2: Front-End electronics, detector control system

> Roma-3: Detector assembling, experiment layout, HV system, trigger distribution.

8. Innovative instruments

The ARGO-YBJ experiment has developed

- a solid large area RPC detector [280x125 cm2, active area ~ 98 % ] with both digital (linearity up to ~ 10 p/m2) and analog (up to 104 p/m2) read-out, 1.3 ns time resolution (measured at YangBaJing Laboratory), current read-out for control of the detector operation
- electronics to handle the RPCs signal (custom design)
- DAQ system with 10 MB/s capability

Many of the technical solutions could be of general interest for experiments aiming to fully exploit the RPCs performance

9. Competing experiments

A similar approach to the g -astronomy ("full coverage" detector at high altitude, large field of view, ~ 100 % duty cycle) is already operating (MILAGRO (USA), 2600 m a.s.l., 4800 m2 water pool instrumented with PM tubes + array). The performance of ARGO-YBJ is expected to be definitely better, due to the high space-time granularity as well as to the higher elevation of the experimental site. However, a fast completion and commissioning of the detector is needed.

10. International committee which has reviewed the experiment

The ARGO-YBJ project has been examined and approved by the INFN Committee II and by the CAS Scientific Committee.