JAEA-Conf 2011-002 - 日本原子力研究開発機構

of MeV region with highest cosmic-ray neutron flux. The data provided from theoretical models, however,
are not reliable enough for prediction of fragment production. Therefore, experimental data on
nucleon-induced fragment production are required to establish theoretical models and its parameters that
can cover various energy, target and products.
Several experimental studies reported DDX data for proton induced fragment production.
R.Green et al. gave fragment DDXs of p+Ag reaction for Ep=210, 300 and 480 MeV [2]. S.J.Yennello et al.
gave DDXs of p+Ag for Ep=161 MeV [3]. Recently, H.Machner et al. gave DDXs of p+Al, Co, Au for
Ep=200 MeV [4]. In addition to these works, K.Katitkowski et al. reported mass distribution and energy
spectra of p+Al reaction for Ep=180 MeV [5]. However, it should be noted that there is no data covering
the energy range for tens of MeV to hundreds of MeV and target mass range for light to medium. The
energy and target mass range are important to study transition of reaction mechanism and applicability
statistical methodology for light nuclei. The data for light target nuclei are required to evaluate radiation
effects on an organ.
To meet the requirements, we have conducted measurement of DDXs for fragment production in
intermediate energy, light target nuclei, proton and neutron incidence [8-15]. We have developed Bragg
Curve Counter (BCC) which has large solid angle and particle identification capability without additional
detectors. The energy dynamic range, however, was limited in conventional BCC. Therefore, we have
developed two new methods [8,9] to extend the energy dynamic range as described in the next section.
In this paper, we report recent fragment DDX measurements using the BCC, for proton-induced
reaction on C, N, O, Al, Ti and Cu targets at 40-300 MeV region. The data of the Al(p,x) reaction for 200
MeV at 30,60,90,120 and the C(p,xLi) for 40-200 MeV at 30 are shown as typical examples of results.
2. Experimental
The present experiments were
performed using the NIRS 930 cyclotron in
National Institute of Radiological Science
(NIRS) for 40-80 MeV protons and the ring
cyclotron in Research Center for Nuclear
Physics (RCNP), Osaka University for
140-300 MeV protons. Details of the BCC
and experimental system employing it were
described in references [8,9]. In this section,
outline of this system is described.
Figure 1 shows plan view of the
experimental setup at RCNP. Proton beam
was focused to 1 mm diameter spot at the
target foil that is mounted on a target
JAEA-Conf 2011-002
Fig.1 Plan view of experimental setup on ENN
beam course in RCNP