Grant: Subatomic Physics Envelope - Project

There are many reactions in nuclear physics and astrophysics in which heavy particles are emitted after the reaction has occurred. These are of the type (alpha,p) and (p,alpha) for direct stellar reactions. In addition, nuclear transfer reactions like (^6Li,d) and (^3He,d), as well as the measurement of elastic scattering can provide useful nuclear information to derive stellar reaction rates. In all cases, the detection of charged light ejectiles is required. A special case are (alpha,n) reactions where we plan not to detect the neutron but the heavy reaction partner. For all these types of reactions we have two detector facilities available: Tuda and Tactic. Tuda is a sophisticated vacuum chamber that allows the placement of various kinds of silicon detectors. This year has seen infrastructure at ISAC II been set in place that allows Tuda to be moved between ISAC I for low energy experiments and ISAC II for high energy experiments. In the past three years, we also have developed a gas based time projection chamber named Tactic. This chamber has a non beam-sensible zone in the centre and no windows toward the outer detecting zone. Thus heavy ions from reactions that occur in the central region can be detected with high efficiency once they scatter into the detection region. Frequently, the emission of charged particles is followed by the emission of gamma rays. We have employed the Dragon BGO array. However, the existing BGO array has too few detectors to allow coverage of the Tactic detector. We therefore request the acquisition of two LaBr detectors for test purposes. LaBr detectors have very good time resolution, as well as good energy resolution combined with a high efficiency. Among the reactions we plan to measure with Tuda are those concerning the breakout from the hot CNO cycle via 18Ne. An indirect measurement of the 14C(a,g)18O stellar rate is planned (AV canum veneticorum stars). We also will provide some support for groups coming to Tuda from abroad. For Tactic a measurement of 8Li(a,n)11B reaction is planned. Also measurements of the 7(Be(p,p)7Be and 7Li(3He,a)6Li reactions are planned. The latter reaction requires a separation of the beam and the detection zone in Tactic and thus another gas handling system.