A new experiment for the determination of the 18F(p,alpha) reaction rate at nova temperatures

The 18F(p,alpha) reaction was recognized as one of the most important for gamma ray astronomy in novae as it governs the early 511 keV emission. However, its rate remains largely uncertain at nova temperatures. A direct measurement of the cross section over the full range of nova energies is impossible because of its vanishing value at low energy and of the short 18F lifetime. Therefore, in order to better constrain this reaction rate, we have performed an indirect experiment taking advantage of the availability of a high purity and intense radioactive 18F beam at the Louvain La Neuve RIB facility. We present here the first results of the data analysis and discuss the consequences.Comment: Contribution to the Classical Novae Explosions conference, Sitges, Spain, 20-24 May 2002, 5 pages, 3 figure

An injector cyclotron for CYCLONE

A heavy ions facility for CYCLONE (Belgium) is described. It consists of an injector cyclotron, able to accelerate heavy ions to a K value of 70 MeV Q/sup 2//A, with an upgrading possibility of 100 MeV Q/sup 2//A. Expected intensities are large. Some design aspects are described, allowing the cost of the project to be quite low.Anglai

[Precise calibration of quadrature transformer]

The accurate calibration of a quadrature-transformer (or three phase-two phase converter) requires the measurement of amplitude - and phase errors at the output. These errors have to be corrected with a measurement of the three-phase unbalance at the input. Two methods are described. The first one is based on the measurement of RMS value of different voltages, by means of a thermocouple, the second one uses an impedance `bridge'. A critical analysis of both methods gives an accuracy of about 0.5 for each of them.Francai

ECR ion sources and rare isotope beams at Louvain-la-Neuve

Electron cyclotron resonance (ECR) ion sources are used in a variety of applications. A lot of them are put to work to ionize abundant isotopes at high intensity and/or high charge states. But another important field for these kinds of sources is also to ionize, with high efficiency, isotopes which are available only in very small quantities, e.g., radioactive isotopes or stable isotopes with very small abundances. At Louvain-la-Neuve a range of different "exotic" beams are accelerated using two types of ECR ion sources. Each element requires the use of some unique method in preparing, operating, or tuning the source. Examples of the use of ECR sources for gaseous exotic isotope ionization include: the production of low charge state Ar-37 (t(1/2)=35 days) and 170 (natural abundance 0.038%) for implantation purposes and short-lived He-6 (t(1/2)=0.8 s) for postacceleration. The sputtering method has been used for the production of Ni-64 beams (0.91% natural abundance) and Be-7 beams (t(1/2)=53 days). Some aspects of the tuning, preparation, and performance of the ECR sources and the configuration and preparation of the sputtering apparatus will be discussed. (C) 2002 American Institute of Physics

Heavy ion acceleration at CYCLONE (Belgium)

CYCLONE is an isochronous cyclotron in operation in Louvain-la-Neuve (Belgium). It is equipped with a P.I.G. hot cathode heavy ion source and accelerates various ions up to energies of 110 MeV Q/sup 2//A with extracted beam intensities reaching 10 mu A in the 4/sup +/ state. The source is described and some performance parameters are given. In order to reach higher charge states, an injector cyclotron is proposed which will allow a final energy of 27 MeV/nucleon up to neon decreasing to 6 MeV/nucleon for xenon. Extracted intensities vary between 5*10/sup 13/ and 10/sup 9/ pps depending on particle and energy. Some design aspects are described.Anglai