Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1682566 | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms | 2009 | 5 Pages |
Abstract
A thin germanium crystal has been irradiated at GANIL by Pb beams of 29 MeV/A (charge state Qin = 56 and 72) and of 5.6 MeV/A (Qin = 28). The induced ion emission from the sample entrance surface was studied, impact per impact, as a function of Qin, velocity vin and energy loss ÎE in the crystal. The Pb ions transmitted through the crystal were analyzed in charge (Qout) and energy using the SPEG spectrometer. The emitted ionized species were detected and analyzed in mass by a time-Of-flight multianode detector (LAG). Channeling was used to select peculiar ÎE values in Ge and hence peculiar Pb ion trajectories close to the emitting entrance surface. The experiment was performed in standard vacuum. No Ge emission was found. The dominating emitted species are H+ and hydrocarbon ions originating from the contamination layer on top of the crystal. The mean value ãMã of the number of detected species per incoming Pb ion (multiplicity) varies as (Qin/vin)p, with p values in agreement with previous results. We have clearly observed an influence of the energy deposition ÎE in Ge on the emission from the top contamination layer. When selecting increasing values of ÎE, we observed a rather slow increase of ãMã. On the contrary, the probabilities of high multiplicity values, which are essentially connected to fragmentation after emission, strongly increase with ÎE.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Surfaces, Coatings and Films
Authors
A. L'Hoir, C. Koumeir, S. Della Negra, P. Boduch, P. Roussel-Chomaz, A. Cassimi, M. Chevallier, C. Cohen, D. Dauvergne, M. Fallavier, D. Jacquet, B. Manil, J.-C. Poizat, C. Ray, H. Rothard, D. Schmaus, M. Toulemonde,