1,037 research outputs found
Production cross-sections and momentum distributions of fragments from neutron-deficient 36Ar at 1.05 A.GeV
We have measured production cross sections and longitudinal momentum
distributions of fragments from neutron-deficient 36Ar at 1.05 A.GeV. The
production cross-sections show excellent agreement with the predictions of the
semiempirical formula EPAX. We have compared these results, involving extremly
neutron deficient nuclei, with model calculations to extract informa tion about
the response of these models close to the driplines. The longitudinal momentum
distributions have also been extracted and are compared with the Goldhaber and
Morrissey systematics.Comment: 16 pages, 6 figure
Towards portable muography with small-area, gas-tight glass Resistive Plate Chambers
Imaging techniques that use atmospheric muons, collectively named under the
neologism "muography", have seen a tremendous growth in recent times, mainly
due to their diverse range of applications. The most well-known ones include
but are not limited to: volcanology, archaeology, civil engineering, nuclear
reactor monitoring, nuclear waste characterization, underground mapping, etc.
These methods are based on the attenuation or deviation of muons to image large
and/or dense objects where conventional techniques cannot work or their use
becomes challenging.
In this context, we have constructed a muography telescope based on "mini
glass-RPC planes" following a design similar to the glass-RPC detectors
developed by the CALICE Collaboration and used by the TOMUVOL experiment in the
context of volcano radiography, but with smaller active area (16 16
cm). The compact size makes it an attractive choice with respect to other
detectors previously employed for imaging on similar scales. An important
innovation in this design is that the detectors are sealed. This makes the
detector more portable and solves the usual safety and logistic issues for gas
detectors operated underground and/or inside small rooms. This paper provides
an overview on our guiding principles, the detector development and our
operational experiences. Drawing on the lessons learnt from the first
prototype, we also discuss our future direction for an improved second
prototype, focusing primarily on a recently adopted serigraphy technique for
the resistive coating of the glass plates.Comment: 8 pages, 7 figures, XV Workshop on Resistive Plate Chambers and
Related Detectors (RPC2020
Charge density distributions and related form factors in neutron-rich light exotic nuclei
Charge form factors corresponding to proton density distributions in exotic
nuclei, such as He, Li, B and Be are calculated
and compared. The results can be used as tests of various theoretical models
for the exotic nuclei structure in possible future experiments using a
colliding electron-exotic nucleus storage ring. The result of such a comparison
would show the effect of the neutron halo or skin on the proton distributions
in exotic nuclei.Comment: 11 pages, 4 figures, to be published in International Journal of
Modern Physics
Production of new neutron-rich isotopes of heavy elements in fragmentation reactions of U projectiles at 1 A GeV
The production of heavy neutron-rich nuclei has been investigated using cold
fragmentation reactions of U projectiles at relativistic energies. The
experiment performed at the high-resolving-power magnetic spectrometer FRS at
GSI allowed to identify 45 new heavy neutron-rich nuclei: Pt,
Au, Hg, Tl, Pb, Bi,
Po, At, Rn and Fr. The production
cross sections of these nuclei were also determined and used to benchmark
reaction codes that predict the production of nuclei far from stability.Comment: 5 pages, 2 figure
Calculations of He+p elastic scattering cross sections using folding approach and high-energy approximation for the optical potential
Calculations of microscopic optical potentials (OP's) (their real and
imaginary parts) are performed to analyze the He+p elastic scattering data
at a few tens of MeV/nucleon (MeV/N). The OP's and the cross sections are
calculated using three model densities of He. Effects of the regularization
of the NN forces and their dependence on nuclear density are investigated.
Also, the role of the spin-orbit terms and of the non-linearity in the
calculations of the OP's, as well as effects of their renormalization are
studied. The sensitivity of the cross sections to the nuclear densities was
tested and one of them that gives a better agreement with the data was chosen.Comment: 13 pages, 11 figures, to be published in Eur. Phys. J.
Chiral three-nucleon forces and bound excited states in neutron-rich oxygen isotopes
We study the spectra of neutron-rich oxygen isotopes based on chiral two- and
three-nucleon interactions. First, we benchmark our many-body approach by
comparing ground-state energies to coupled-cluster results for the same
two-nucleon interaction, with overall good agreement. We then calculate bound
excited states in 21,22,23O, focusing on the role of three-nucleon forces, in
the standard sd shell and an extended sdf7/2p3/2 valence space. Chiral
three-nucleon forces provide important one- and two-body contributions between
valence neutrons. We find that both these contributions and an extended valence
space are necessary to reproduce key signatures of novel shell evolution, such
as the N = 14 magic number and the low-lying states in 21O and 23O, which are
too compressed with two-nucleon interactions only. For the extended space
calculations, this presents first work based on nuclear forces without
adjustments. Future work is needed and open questions are discussed.Comment: 6 pages, 4 figures, published versio
Breakup of loosely bound nuclei as indirect method in nuclear astrophysics: 8B, 9C, 23Al
We discuss the use of one-nucleon breakup reactions of loosely bound nuclei
at intermediate energies as an indirect method in nuclear astrophysics. These
are peripheral processes, therefore we can extract asymptotic normalization
coefficients (ANC) from which reaction rates of astrophysical interest can be
inferred. To show the usefulness of the method, three different cases are
discussed. In the first, existing experimental data for the breakup of 8B at
energies from 30 to 1000 MeV/u and of 9C at 285 MeV/u on light through heavy
targets are analyzed. Glauber model calculations in the eikonal approximation
and in the optical limit using different effective interactions give
consistent, though slightly different results, showing the limits of the
precision of the method. The results lead to the astrophysical factor
S_17(0)=18.7+/-1.9 eVb for the key reaction for solar neutrino production
7Be(p,\gamma)8B. It is consistent with the values from other indirect methods
and most direct measurements, but one. Breakup reactions can be measured with
radioactive beams as weak as a few particles per second, and therefore can be
used for cases where no direct measurements or other indirect methods for
nuclear astrophysics can be applied. We discuss a proposed use of the breakup
of the proton drip line nucleus 23Al to obtain spectroscopic information and
the stellar reaction rate for 22Mg(p,\gamma)23Al.Comment: 6 pages, 4 figures. Presented at the conference "Nuclear Physics for
Astrophysics 2", Debrecen, Hungary, May 2005. Prepared for the Proceeding
Investigation of the 6He cluster structures
The 4He+2n and t+t clustering of the 6He ground state were investigated by
means of the transfer reaction 6He(p,t)4He at 25 MeV/nucleon. The experiment
was performed in inverse kinematics at GANIL with the SPEG spectrometer coupled
to the MUST array. Experimental data for the transfer reaction were analyzed by
a DWBA calculation including the two neutrons and the triton transfer. The
couplings to the 6He --> 4He + 2n breakup channels were taken into account with
a polarization potential deduced from a coupled-discretized-continuum channels
analysis of the 6He+1H elastic scattering measured at the same time. The
influence on the calculations of the 4He+t exit potential and of the triton
sequential transfer is discussed. The final calculation gives a spectroscopic
factor close to one for the 4He+2n configuration as expected. The spectroscopic
factor obtained for the t+t configuration is much smaller than the theoretical
predictions.Comment: 10 pages, 11 figures, accepted in PR
Elastic and total reaction cross sections of oxygen isotopes in Glauber theory
We systematically calculate the total reaction cross sections of oxygen
isotopes, O, on a C target at high energies using the Glauber
theory. The oxygen isotopes are described with Slater determinants generated
from a phenomenological mean-field potential. The agreement between theory and
experiment is generally good, but a sharp increase of the reaction cross
sections from ^{21}O to ^{23}O remains unresolved. To examine the sensitivity
of the diffraction pattern of elastic scattering to the nuclear surface, we
study the differential elastic-scattering cross sections of proton-^{20,21,23}O
at the incident energy of 300 MeV by calculating the full Glauber amplitude.Comment: 9 pages, 8 figure
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