Last Update: October 2000

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

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

Institutions:

> 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

> IHEP, Beijing

> Shandong University, JiNan

> South West Jiaotong University, Chengdu

> Tibet University, Lhasa

> Yunnan University, Kunming

> Zhenghou University, Henan

1. Goal of the experiment

Observation of galactic and extragalactic neutral and charged radiation in the energy range 100 GeV - 20 TeV.

Main Scientific goals:

- g -astronomy,

> search and monitoring of the Northern sky sources (-10° £ d £ 70°) at 100 GeV energy threshold with ~ 1/10 Crab flux sensitivity.

- diffuse g -rays,

> from the Galactic plane, SuperNova Remnants, molecular clouds at energies >=100 GeV (never observed so far).

- GRB physics,

> extending the satellite measurements over the full GeV/TeV range.

- anti-p/p ratio,

> at energies ~ 1 TeV with a sensitivity adequate to distinguish between models of local (galactic) anti-p production and models accounting for an extragalactic origin.

- Primary proton spectrum,

> in the 10 - 200 TeV energy range, with size reconstruction accuracy better than 10 % and sensitivity sufficient to detect a sharp change of the slope of the energy spectrum.

- Solar and Heliospheric physics,

> including cosmic ray modulation phenomena at an energy threshold of ~ 10 GeV, large scale structures of the interplanetary medium, high energy solar gamma-rays and neutrons.

2. Physics achievements during the 2000

The 2000 activity has been addressed to the following technical items:

- Development of the Front-End electronics cards [Roma-2]
- Development of the Receiver card, TDC card for the Local Station electronics (the electronics devoted to handle the signal from the Cluster, the basic logic unit of 12 RPCs) [Lecce]
- Study of the multiplicity card which sends to the Central Station the information concerning the Cluster multiplicity [Lecce]
- Development of the trigger supervisor and construction of part of the I/O cards (ARGO-MEMORY BOX, AMB) of the Central Station [Napoli]
- Final design of the gas distribution system and test of the Cluster gas distribution [Napoli]
- Assembling and test of the final "ARGO" RPC prototype with the gas volume and the read-out strips, including the Front-End electronics, enclosed in a rigid frame [Roma-2, Roma-3]
- Study of the RPC analog read-out by two 140 ´ 125 cm2 "BIG PAD" [Roma-2, Napoli]
- Development of the final layout of the "ARGO" RPC [Roma-3]
- Design of the HV distribution system and test of the distribution box [Roma-3]
- Development of the semi-automatic station for soldering the electronics cards to the strip panel [Roma-2]
- Construction of 40 RPCs
- Start of the installation in November 2000

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

- Manpower: 43 researchers (21.7 FTE), 2 technologists (0.7 FTE), 9 technicians (3.05 FTE).
- Support from the mechanics and electronics workshops of Napoli and Roma-2.
- Financial support (2000): 1812 MLit.

4. Number of publications in refereed journal: 6

5. Number of talks to conferences: 12

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

- n. 2 Ph.D.;
- n. 7 Laurea diplomas.

7. Leadership role 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.