Status of high intensity proton injector for Facility for Antiproton and Ion Research

Abstract

The high intensity proton injector for the international accelerator Facility for Antiproton and Ion Research located at GSI-Darmstadt in Germany consists of a pulsed 2.45 GHz microwave ion source, a Low Energy Beam Transport (LEBT), and an electrostatic chopper matching the proton beam to the radio frequency quadrupole. The ion source is based on electron cyclotron resonance plasma production and it has to provide a proton beam at 95 keV energy and up to 100 mA current. The LEBT system with two short solenoids each including two magnetic steerers will transport the proton beam into the compact proton linac, accelerating it to the energy of 68 MeV and serving as the injector of the upgraded heavy ion synchrotron (SIS18). This paper describes the commissioning of the proton injector including beam characterization measurements that have been done at CEA/Saclay in France and is currently at the final commissioning stage.

The Status and Future of Direct Nuclear Reaction Measurements for Stellar Burning

“…Carbon fusion in stars proceeds primarily through the 12 C( 12 C, α) 20 Ne and the 12 C( 12 C, p) 23 Na reactions. SN progenitor models require the rates of these reactions to be known down to E cm ∼ 1.2 MeV.…”

“…The most efficient urca shells are those associated to the pairs 23 Na↔ 23 Ne and 21 Ne↔ 21 F. There is remarkable feedback with the 12 C+ 12 C reaction [113], as 23 Na is directly produced via the p channel, while 21 Ne is synthesized via n captures on the 20 Ne produced by the α channel. An enhanced value of the 12 C+ 12 C astrophysical factor at E cm < 2 MeV would hasten the C ignition and the C burning will occur at lower density, thus reducing the amount of energy released by the electron captures near the center.…”

“…In the case of the 24 Mg compound nucleus, the 12 C+ 12 C collision represents the entrance channel. Possible asymptotically closed channels are: 23 Na+p, 20 Ne+α, and even 23 Mg+n. In the case of the 22 Ne+α reactions, the asymptotically closed channels may be 21 Ne+n and 22 Ne+γ.…”

Beam dynamics design of the FAIR proton-linac RFQ and design study of a compact 325 MHz RFQ

“…Eine umfassende theoretische Beschreibung der beschleunigenden und fokussierenden elektrischen 20 Felder im RFQ ist ebenfalls unerlässlich für ein tieferes Verständnis der Strahldyna- Ferner werden in diesem Kapitel Simulationsreihen, die auf von der Ionenquellen-Gruppe der GSI zur Verfügung gestellten Messungen im LEBT-Abschnitt am CEA Saclay fußen [25], beschrieben und deren Ergebnisse mit den Simulationsergebnissen verglichen, die auf generischen RFQ-Eingangsverteilungen 33 basieren. Hierzu war es auch erforderlich, die in der LEBT-Sektion von R. Berezov et al gemessen Verteilungen in den TraceWin-Code 34 einzulesen.…”

“…It eventually gave rise to the so-called New Four Section Procedure (NFSP) 25 developed by A. Schempp and C. Zhang at IAP Frankfurt [16]. Its main features are [67]: variation of focusing strength B in accordance with the changes in the space-charge forces along the RFQ and an according retuning of the synchronous phases' evolution speed for an improved bunching process [16].…”