573 research outputs found
Pion Compton scattering and bremsstrahlung
The pion-polarizability functions are structure functions of pion-Compton
scattering. They can be assessed in high-energy pion-nucleus bremsstrahlung
reactions, . We present numerical expectations for
pion-nucleus bremsstrahlung cross sections in the Coulomb region, i.e. the
small-angle region where the nuclear scattering is dominated by the Coulomb
interaction. We investigate the prospects of measuring the polarizability
functions for pion-Compton c.m. energies from threshold up to 1 GeV. A
meson-exchange model is used for the pion-Compton amplitude.Comment: 20 pages, 11 figure
Hard pion bremsstrahlung in the Coulomb region
Hard high-energy pion-nucleus bremsstrahlung, ,
is studied in the Coulomb region, i.e. the small-angle region where the nuclear
scattering is dominated by the Coulomb interaction. Special attention is
focussed on the possibility of measuring the pion polarizability in such
reactions. We study the sensitivity to the structure of the underlying the
pion-Compton amplitude through a model with , , and a_1
exchanges. It is found that the effective energy in the virtual pion-Compton
scattering is often so large that the threshold approximation does not apply.Comment: 18 pages, 5 figure
Coulomb-nuclear interference in pion-nucleus bremsstrahlung
Pion-nucleus bremsstrahlung offers a possibility of measuring the structure
functions of pion-Compton scattering from a study of the
small-momentum-transfer region where the bremsstrahlung reaction is dominated
by the single-photon-exchange mechanism. The corresponding cross-section
distribution is characterized by a sharp peak at small momentum transfers. But
there is also a hadronic contribution which is smooth and constitutes an
undesired background. In this communication the modification of the
single-photon exchange amplitude by multiple-Coulomb scattering is investigated
as well as the Coulomb-nuclear interference term.Comment: 21 pages, 5 figures. Eqs.(51,52) corrected; some new figure
Resonance Excitations in Be 7 (d,p) Beâ 8 to Address the Cosmological Lithium Problem
6 pags., 5 figs., 3 tabs.The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial Li7 abundance in standard big-bang nucleosynthesis. Prior measurements of the Be7(d,p)Beâ8 reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at Ec.m.=7.8 MeV, populating excitations up to 22 MeV in Be8 for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the talys code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy.D. G. acknowledges research funding from the European Unionâs Horizon 2020 research and innovation programme
under Grant Agreement No. 654002 (ENSAR2) and ISRO, Government of India under Grant No. ISRO/RES/2/378/
15â16. O. T. would like to acknowledge the support by the Spanish Funding Agency (AEI/FEDER, EU) under
the project PID2019â104390GB-I00. I. M. would like to acknowledge the support by the Ministry of Science,
Innovation and Universities of Spain (Grant No. PGC2018-095640-B-I00). J. C. acknowledges grants
from the Swedish Research Council (VR) under Contracts No. VR-2017-00637 and No. VR-2017-03986 as well as
grants from the Royal Physiographical Society. J. P. would like to acknowledge the support by Institute for Basic
Science (IBS-R031-D1). S. S. acknowledges support by the Academy of Finland (Grant No. 307685)
Deformation of the N=Z nucleus 76Sr using beta-decay studies
A novel method of deducing the deformation of the N=Z nucleus 76Sr is
presented. It is based on the comparison of the experimental Gamow-Teller
strength distribution B(GT) from its beta decay with the results of QRPA
calculations. This method confirms previous indications of the strong prolate
deformation of this nucleus in a totally independent way. The measurement has
been carried out with a large Total Absorption gamma Spectrometer, "Lucrecia",
newly installed at CERN-ISOLDE.Comment: Accepted in Phys. Rev. Letter
Positron-neutrino correlation in the 0^+ \to 0^+ decay of ^{32}Ar
The positron-neutrino correlation in the decay of
Ar was measured at ISOLDE by analyzing the effect of lepton recoil on
the shape of the narrow proton group following the superallowed decay. Our
result is consistent with the Standard Model prediction. For vanishing Fierz
interference we find , which yields improved
constraints on scalar weak interactions
Study of elastic and inelastic scattering of 7Be + 12C at 35 MeV
6 pags., 5 figs., 2 tabs.The elastic and inelastic scattering of Be from C have been measured at an incident energy of 35 MeV. The inelastic scattering leading to the 4.439 MeV excited state of C has been measured for the first time. The experimental data cover an angular range of Ξ = 15-120. Optical model analyses were carried out with Woods-Saxon and double-folding potential using the density dependent M3Y (DDM3Y) effective interaction. The microscopic analysis of the elastic data indicates breakup channel coupling effect. A coupled-channel analysis of the inelastic scattering, based on collective form factors, shows that mutual excitation of both Be and C is significantly smaller than the single excitation of C. The larger deformation length obtained from the DWBA analysis could be explained by including the excitation of Be in a coupled-channel analysis. The breakup cross section of Be is estimated to be less than 10% of the reaction cross section. The intrinsic deformation length obtained for the C (4.439 MeV) state is ÎŽ = 1.37 fm. The total reaction cross section deduced from the analysis agrees very well with Wong's calculations for similar weakly bound light nuclei on C target.D. Gupta acknowledges research funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654002 (ENSAR2) and ISRO, Government of India under grant no. ISRO/RES/2/378/15-16. O. Tengblad would like to acknowledge the support by the Spanish Funding Agency (AEI / FEDER, EU) under the project PID2019-104390GB-I00. I. Martel would like to acknowledge the support by the Ministry of Science, Innovation and Universities of Spain (Grant No. PGC2018-095640-B-I00). J. Cederkall acknowledges grants from the Swedish Research Council (VR) under contract numbers VR-2017-00637 and VR-2017-03986 as well as grants from the Royal Physiographical Society. J. Park would like to acknowledge the support by Institute for Basic Science (IBS-R031-D1). S. Szwec acknowledges support by the Academy of Finland (Grant No. 307685). A.M.M. is supported by the I+D+i project PID2020-114687GB-I00 funded by MCIN/AEI/10.13039/501100011033, by the grant Group FQM-160 and by project P20_01247, funded by the ConsejerĂa de EconomĂa, Conocimiento, Empresas y Universidad, Junta de AndalucĂa (Spain) and by âERDF A way of making Europeâ
Study of elastic and inelastic scattering of Be + C at 35 MeV
The elastic and inelastic scattering of Be from C have been
measured at an incident energy of 35 MeV. The inelastic scattering leading to
the 4.439 MeV excited state of C has been measured for the first time.
The experimental data cover an angular range of =
15-120. Optical model analyses were carried out with
Woods-Saxon and double-folding potential using the density dependent M3Y
(DDM3Y) effective interaction. The microscopic analysis of the elastic data
indicates breakup channel coupling effect. A coupled-channel analysis of the
inelastic scattering, based on collective form factors, show that mutual
excitation of both Be and C is significantly smaller than the single
excitation of C. The larger deformation length obtained from the DWBA
analysis could be explained by including the excitation of Be in a
coupled-channel analysis. The breakup cross section of Be is estimated to
be less than 10 of the reaction cross section. The intrinsic deformation
length obtained for the C (4.439 MeV) state is = 1.37
fm. The total reaction cross section deduced from the analysis agrees very well
with Wong's calculations for similar weakly bound light nuclei on C
target.Comment: 8 pages, 5 figure
Crossing the Dripline to 11N Using Elastic Resonance Scattering
The level structure of the unbound nucleus 11N has been studied by 10C+p
elastic resonance scattering in inverse geometry with the LISE3 spectrometer at
GANIL, using a 10C beam with an energy of 9.0 MeV/u. An additional measurement
was done at the A1200 spectrometer at MSU. The excitation function above the
10C+p threshold has been determined up to 5 MeV. A potential-model analysis
revealed three resonance states at energies 1.27 (+0.18-0.05) MeV (Gamma=1.44
+-0.2 MeV), 2.01(+0.15-0.05) MeV, (Gamma=0.84 +-$0.2 MeV) and 3.75(+-0.05) MeV,
(Gamma=0.60 +-0.05 MeV) with the spin-parity assignments I(pi) =1/2+, 1/2- and
5/2+, respectively. Hence, 11N is shown to have a ground state parity inversion
completely analogous to its mirror partner, 11Be. A narrow resonance in the
excitation function at 4.33 (+-0.05) MeV was also observed and assigned
spin-parity 3/2-.Comment: 14 pages, 9 figures, twocolumn Accepted for publication in PR
, and the neutrino mass hierarchy at a double baseline Li/B -Beam
We consider a -Beam facility where Li and B ions are
accelerated at , accumulated in a 10 Km storage ring and let
decay, so as to produce intense and beams. These beams
illuminate two iron detectors located at Km and
Km, respectively. The physics potential of this setup is analysed in full
detail as a function of the flux. We find that, for the highest flux ( ion decays per year per baseline), the sensitivity to
reaches ; the sign of
the atmospheric mass difference can be identified, regardless of the true
hierarchy, for ; and, CP-violation
can be discovered in 70% of the -parameter space for , having some sensitivity to CP-violation down to
for .Comment: 35 pages, 20 figures. Minor changes, matches the published versio
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