448 research outputs found
Two Proton Emission with Electromagnetic Probes
A model to study two-proton emission from nuclei induced by electromagnetic
probes is developed. The process is due to one-body electromagnetic operators,
acting together with short-range correlations, and two-body currents.
The model includes all the diagrams containing a single correlation function.
The sensitivity of the cross section to the details of the correlation function
is studied by using realistic and schematic correlations. Results for the
O nucleus are presented.Comment: 9 pages, 8 figures, Contribution to the 6th. Workshop on
"Electromagnetic Induced Two-Hadron Emission",Pavia, 200
Computation of the electron beam quality factors for the NE2571, NE2571A and NE2581A thimble ionization chambers using PENELOPE
The quality correction factor for electron beams was calculated
for three thimble ionization chambers, namely, NE2571, NE2571A and NE2581A. The
Monte Carlo code PENELOPE was used to estimate the overall correction factor
of these chambers for electron beams with nominal energies
ranging between 6 and 22 MeV, corresponding to a Varian Clinac 2100 C/D. A
Co beam was used as reference quality . Also eight
monoenergetic electron beams reproducing the quality index of the
Clinac beams were considered. The factors were calculated as the
ratio between and . Those obtained for the
NE2571 ionization chamber show a nice agreement with those calculated by Muir
and Rogers with EGSnrc. As it occurred to other ionization chambers analyzed in
previous works, the factors found for the monoenergetic beams
are larger (smaller) than those corresponding to the Clinac beams at low (high)
values, the differences being slightly above . Finally, the
factors obtained in the case of the NE2571A chamber are
systematically ~0.5% below those of its predecessor chamber, the NE2571.Comment: 8 pages, 2 figures, 3 table
Photo-emission of two protons from nuclei
The photo-emission of two protons from the C, O and Ca
nuclei is investigated. Aim of the work is the study of the possibilities
offered by this probe to obtain information about the characteristics of the
short-range correlations. We have also evaluated the effects of the two-body
-currents which, in this processes, compete with those produced by the
short-range correlations. Our results show that (,pp) processes could
be more useful than (e,e'pp) for the study of the short-range correlations.Comment: 21 pages, 15 figures, 3 table
Radiative pion capture in nuclei: a continuum shell-model approach
The radiative pion capture process in nuclei is approached by using a
continuum shell-model description of the nucleus, together with a
phenomenological treatment of the two particle-two hole effects. It is found
that these effects play an important role to reproduce the observed
experimental photon energy distribution. This distribution as well as the
integrated one depends significantly on the details of the mean field
potential. This makes this process interesting to investigate the nuclear
structure dynamics.Comment: 21 pages, LateX file + 5 figures, epsf.st
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