Re: Neutron yields for 10 MeV proton on Cu and Al

Dear Yuanjie,

10 MeV are quite down close to the limit of the proton interaction range,
where cross section high derivative, channel thresholds, nuclear
structure details, subbarrier effects play together and make hard a very
accurate account within a much more extended Monte Carlo model.

More specifically, consider that for Cu the code samples the target
isotope accordind to the natural composition and this way tends to
preferentially choose Cu63, with a (p,n) threshold of about 4 MeV and
consequently a reduced probability of emitting neutrons with respect to
Cu65, for which the neutron production, with a (p,n) threshold of 2 MeV,
turns out to be dominant. Therefore, an underestimation factor of 2-3 can
be logical.
On the other hand, note also that for Al the experimental yield you quote
seems to be extrapolated and not measured.

Cheers

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854
Received on Tue Jan 18 2011 - 12:03:18 CET