g2 production run
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Introduction

The g2 experiment uses a high energy tagged photon beam (up to 3.2 GeV) on a liquid deuterium target. The trigger signal is quite lousy being a single charged particle in CLAS (TOF, Time Of Flight) in coincidence with the tagging system (MOR, Master Or).
G2 is composed by four experiments, running concurrently:

• Study of kaon photoproduction on deuterium, (B. Mecking)
• Photoproduction of Eta mesons from deuterium, (B. Ritchie)
• Inclusive Eta photoproduction in nuclei, (M.F. Vineyard)
• Deuteron photodisintegration at high energy and low momentum transfers  ( E. De Sanctis, P.Rossi)

G2 has collected 2.8 billion events in its first run period during year 1999 (from 08/13/99 -> 08/31/1999 and from 09/13/99 -> 09/27/99). The first run period has covered 75% of the available beam time. The second run for g2 will happen during year 2002 and will collect data for the remaining 25% of the assigned beam time.

Running conditions for the first period of g2 (1999)

• current intensity:10-13 nA;
• Photon energy0.5 -> 3.2 GeV;
• Target: Cilyndrical with length 10 cm and radius2 cm (liquid deuterium);
• First level trigger: [1 charged hit ] (80%) OR [ 2 neutral hits in opposite sectors](20%);
• Beam availability: 85%, Readiness od the experiment : 78%
• List of the August and September runs

Deuteron photodisintegration at high energy

The forth experiment in the above list, aims at measuring the differential cross section for the (gamma d -> p n ) and (gamma d -> p delta0) reactions in the region of small momentum transfers and over the energy range from 0.5 to 3.2 GeV, in order to check the predictions of the Regge phenomenology and the Quark Gluon String (QGS) model [1]. It uses the photon tagger and the CLAS detector at Jefferson Lab  which  allow to obtain data with reduced uncertainties over a broad kinematical region (data accumulated in angular bins of about 10 degrees and energy bins of 100 MeV will have 0.7% and 2.5% statistical errors neglecting background, respectively at the lower and higher ends of the energy range).

Preliminary photodisintegration data analysis

• gd -> p X(n) analysis
• Level II trigger efficiency study and additional  gd -> p X(n), and  gd -> p pi-X( p) analysis
• CLAS simulations for the gd -> p X(n) channel
• Photon flux normalization and cross section calculations

click on the images to enlarge them.

References

[1] L.A. Kondratyuk, E. De Sanctis, A. B. Kaidalov et al.,
     Deuteron photodisintegration, quark-gluon string model, and Regge phenomenology, Phys. Rev. C 48, 2491, 1993

last update by F.Ronchetti on Wednesday, July 19, 2000