Berlin 2005 – scientific programme
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ST: Strahlen- und Medizinphysik
ST 5: Medizinphysik: Strahlentherapie mit Ionen II
ST 5.3: Fachvortrag
Tuesday, March 8, 2005, 11:45–12:00, TU HL1
Measurement and calculation of energy spectra of nuclear fragments from 200 MeV/u 3He stopping in a thick water target — •Hiroshi Iwase and Dieter Schardt — Biophysik, Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt
The new clinical ion-therapy unit HIT presently under construction at the Radiological University Clinics in Heidelberg will provide beams of protons, helium-, carbon- and oxygen-ions for the treatment of deep-seated tumours. For an unambiguous discrimination of these different ions in the low-energy section of the accelerator the isotope 3He is preferred over 4He because of its unique charge/mass ratio. For the physical characterisation of 3He as a therapy beam the nuclear fragmentation in water (used as tissue-equivalent) was investigated experimentally. The measurements were performed in the biophysics cave at GSI Darmstadt using 200 MeV/u 3He beams delivered by the sysnchrotron SIS-18 which were stopped in a 12.78 cm thick water target. Secondary fragments were identified by a telescope detector consisting of a plastic scintillator and a 14 cm thick BaF2 crystal which was placed at angles from 0 to 30 degrees with respect to the beam axis. Another thin plastic scintillator located in front of the target provided the counting of primary ions and the start signal for time-of-flight measurements. The data include energy spectra of neutrons, protons, and deuterons which are produced in nuclear interactions and emerge from the thick water target in forward direction. The results are compared with a calculation by the PHITS code[1], a general-use Monte Carlo transport calculation for particles/heavy ions.
[1] K. Niita et al., JAERI-Conf2004-005, 33, 2004