189 research outputs found
Double Giant Dipole Resonance in ^{208}Pb
Double-dipole excitations in ^{208}Pb are analyzed within a microscopic model
explicitly treating 2p2h-excitations. Collective states built from such
2p2h-excitations are shown to appear at about twice the energy of the isovector
giant dipole resonance, in agreement with the experimental findings. The
calculated cross section for Coulomb excitation at relativistic energies cannot
explain simultaneously the measured single-dipole and double-dipole cross
sections, however.Comment: 7 pages, Latex, 5 postscript figure
Coherent photonuclear reactions for isotope transmutation
Coherent photonuclear isotope transmutation (CPIT) produces exclusively
radioactive isotopes (RIs) by coherent photonuclear reactions via E1 giant
resonances. Photons to be used are medium energy photons produced by laser
photons backscattered off GeV electrons. The cross sections are as large as 0.2
- 0.6 b, being independent of individual nuclides. A large fraction of photons
is effectively used for the photonuclear reactions, while the scattered GeV
electrons remain in the storage ring to be re-used. CPIT with medium energy
photons provides specific/desired RIs with the high rate and the high density
for nuclear science, molecular biology and for nuclear medicines.Comment: 8 pages, 2 figure
Elastic and Raman scattering of 9.0 and 11.4 MeV photons from Au, Dy and In
Monoenergetic photons between 8.8 and 11.4 MeV were scattered elastically and
in elastically (Raman) from natural targets of Au, Dy and In.15 new cross
sections were measured. Evidence is presented for a slight deformation in the
197Au nucleus, generally believed to be spherical. It is predicted, on the
basis of these measurements, that the Giant Dipole Resonance of Dy is very
similar to that of 160Gd. A narrow isolated resonance at 9.0 MeV is observed in
In.Comment: 31 pages, 11 figure
White paper: CeLAND - Investigation of the reactor antineutrino anomaly with an intense 144Ce-144Pr antineutrino source in KamLAND
We propose to test for short baseline neutrino oscillations, implied by the
recent reevaluation of the reactor antineutrino flux and by anomalous results
from the gallium solar neutrino detectors. The test will consist of producing a
75 kCi 144Ce - 144Pr antineutrino source to be deployed in the Kamioka Liquid
Scintillator Anti-Neutrino Detector (KamLAND). KamLAND's 13m diameter target
volume provides a suitable environment to measure energy and position
dependence of the detected neutrino flux. A characteristic oscillation pattern
would be visible for a baseline of about 10 m or less, providing a very clean
signal of neutrino disappearance into a yet-unknown, "sterile" state. Such a
measurement will be free of any reactor-related uncertainties. After 1.5 years
of data taking the Reactor Antineutrino Anomaly parameter space will be tested
at > 95% C.L.Comment: White paper prepared for Snowmass-2013; slightly different author
lis
CeLAND: search for a 4th light neutrino state with a 3 PBq 144Ce-144Pr electron antineutrino generator in KamLAND
The reactor neutrino and gallium anomalies can be tested with a 3-4 PBq
(75-100 kCi scale) 144Ce-144Pr antineutrino beta-source deployed at the center
or next to a large low-background liquid scintillator detector. The
antineutrino generator will be produced by the Russian reprocessing plant PA
Mayak as early as 2014, transported to Japan, and deployed in the Kamioka
Liquid Scintillator Anti-Neutrino Detector (KamLAND) as early as 2015.
KamLAND's 13 m diameter target volume provides a suitable environment to
measure the energy and position dependence of the detected neutrino flux. A
characteristic oscillation pattern would be visible for a baseline of about 10
m or less, providing a very clean signal of neutrino disappearance into a
yet-unknown, sterile neutrino state. This will provide a comprehensive test of
the electron dissaperance neutrino anomalies and could lead to the discovery of
a 4th neutrino state for Delta_m^2 > 0.1 eV^2 and sin^2(2theta) > 0.05.Comment: 67 pages, 50 figures. Th. Lasserre thanks the European Research
Council for support under the Starting Grant StG-30718
A FABRY-PEROT CAVITY FOR COMPTON POLARIMETRY
A new kind of Compton polarimeter using a resonant Fabry—Pe« rot cavity as a power buildup for the photon beam is proposed. A prototype of such a cavity is described, along with the results obtained in terms of source to be used in a Compton scattering polarimeter. ( 1998 Elsevier Science B.V. All rights reserved
Measurement of Mutual Coulomb Dissociation in GeV Au+Au collisions at RHIC
We report on the first measurement of Mutual Coulomb Dissociation in heavy
ion collisions. We employ forward calorimeters to measure neutron multiplicity
at beam rapidity in peripheral collisions. The cross-section for simultaneous
electromagnetic breakup of Au nuclei at GeV is
barns in good agreement with calculations.Comment: This paper has been submitted for publication in Phys. Rev. Let
SPIRAL II Project (electron option) - Preliminary Design Study
This document presents a Preliminary Design Study (PDS) of the electron option of the SPIRAL II project
Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
The Double Chooz Experiment presents an indication of reactor electron
antineutrino disappearance consistent with neutrino oscillations. A ratio of
0.944 0.016 (stat) 0.040 (syst) observed to predicted events was
obtained in 101 days of running at the Chooz Nuclear Power Plant in France,
with two 4.25 GW reactors. The results were obtained from a single 10
m fiducial volume detector located 1050 m from the two reactor cores. The
reactor antineutrino flux prediction used the Bugey4 measurement as an anchor
point. The deficit can be interpreted as an indication of a non-zero value of
the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate
of the prompt positrons and their energy spectrum we find \sang = 0.086
0.041 (stat) 0.030 (syst), or, at 90% CL, 0.015 \sang 0.16.Comment: 7 pages, 4 figures, (new version after PRL referee's comments
Site testing for submillimetre astronomy at Dome C, Antarctica
Over the past few years a major effort has been put into the exploration of
potential sites for the deployment of submillimetre astronomical facilities.
Amongst the most important sites are Dome C and Dome A on the Antarctic
Plateau, and the Chajnantor area in Chile. In this context, we report on
measurements of the sky opacity at 200 um over a period of three years at the
French-Italian station, Concordia, at Dome C, Antarctica. We also present some
solutions to the challenges of operating in the harsh polar environ- ment. Dome
C offers exceptional conditions in terms of absolute atmospheric transmission
and stability for submillimetre astron- omy. Over the austral winter the PWV
exhibits long periods during which it is stable and at a very low level (0.1 to
0.3 mm). Higher values (0.2 to 0.8 mm) of PWV are observed during the short
summer period. Based on observations over three years, a transmission of around
50% at 350 um is achieved for 75% of the time. The 200-um window opens with a
typical transmission of 10% to 15% for 25% of the time. Dome C is one of the
best accessible sites on Earth for submillimetre astronomy. Observations at 350
or 450 {\mu}m are possible all year round, and the 200-um window opens long
enough and with a sufficient transparency to be useful. Although the polar
environment severely constrains hardware design, a permanent observatory with
appropriate technical capabilities is feasible. Because of the very good
astronomical conditions, high angular resolution and time series (multi-year)
observations at Dome C with a medium size single dish telescope would enable
unique studies to be conducted, some of which are not otherwise feasible even
from space
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