Darmstadt 2008 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 12: Instrumentation und Anwendungen II
HK 12.4: Talk
Monday, March 10, 2008, 17:30–17:45, 2D
Trigger design for HypHI project — •Christophe Rappold for the HypHI collaboration — GSI, Darmstadt, Germany — Univ. Louis Pasteur, Strasbourg, France
The HypHI project aims to study hypernuclei by means of collisions of stable heavy ion and rare-isotope beams on stable target materials. Thanks to this production mechanism, hypernuclei are produced around at the projectile rapidity with a projectile fragmentation and a coalescence of a Λ-hyperon in the fragment, thus giving an opportunity to investigate hypernuclei at extreme isospins and to measure directly hypernuclear magnetic moments.
As the first step (Phase 0), the feasibility of hypernuclear spectroscopy with heavy ion beams will be demonstrated with a 6Li beam at 2 A GeV impinged on a 12C target by identifying Λ 3H, Λ 4H and Λ 5He hypernuclei from their mesonic decay modes.
The yield is expected to be a few thousands per week for a 107/s beam intensity on a target with a thickness of 8 g/cm2. An effective trigger system is crucial for feasibility of Phase 0 experiment since the hypernuclear production cross section is seven order of magnitude lower than the cross section for background events. The proposed trigger system consists of three simultaneous stages: a tracking trigger for secondary vertexes selections for Λ and hypernuclear decay, a π− trigger to select π − with high momenta from the decay of hypernuclei and a Z=2 trigger to select residues of hypernuclear decay.
In this presentation, the design study and performance of the trigger system will be discussed.