55 research outputs found
Investigation of decay in Nd and Nd to the excited states of daughter nuclei
Double beta decay of Nd and Nd to the excited states of
daughter nuclei have been studied using a 400 cm low-background HPGe
detector and an external source consisting of 3046 g of natural NdO
powder. The half-life for the two-neutrino double beta decay of Nd to
the excited 0 state in Sm is measured to be
y.
For other transitions to the 2, 2, 2, and
0 levels in Sm, limits are obtained at the level of y. In the case of Nd only limits for the transitions to the 2, 0, and 2 excited states in
Sm were obtained and are at the level of \sim (4-8)\cdot 10^{20}$ y.Comment: 13 pages, 6 figure
Search for EC and ECEC processes in Sn
Limits on EC (here EC denotes electron capture) and ECEC processes
in Sn have been obtained using a 380 cm HPGe detector and an
external source consisting of 53.355 g enriched tin (94.32% of Sn). A
limit with 90% C.L. on the Sn half-life of y for
the ECEC(0) transition to the excited state in Cd (1871.0
keV) has been established. This transition is discussed in the context of a
possible enhancement of the decay rate by several orders of magnitude given
that the ECEC process is nearly degenerate with an excited state in the
daughter nuclide. Prospects for investigating such a process in future
experiments are discussed. The limits on other EC and ECEC processes
in Sn were obtained on the level of y at the
90% C.L.Comment: 14 pages, 4 figure
Search for EC and ECEC processes in Se
For the first time, limits on double-beta processes in Se have been
obtained using a 400 cm HPGe detector and an external source consisting of
natural selenium powder.
At a confidence level of 90%, they are y for the
EC transition to the ground state,
y for the ECEC() transition to the excited state in Ge
(595.8 keV), y for the ECEC() transition to the
excited state in Ge (595.8 keV) and y for
the ECEC() and ECEC() transitions to the excited state in
Ge (1204.2 keV). The last transition is discussed in association with a
possible enhancement of the decay rate, in this case by several orders of
magnitude, because the ECEC process is nearly degenerate with an
excited state in the daughter nuclide. Prospects for investigating such
processes in future experiments are discussed.Comment: 13 pages, 2 figures; presented at the 2-nd Symposium on "Neutrino and
Dark Matter in Nuclear Physics" (Paris, September 3-9, 2006); v3: minor
change
Search for EC and ECEC processes in Sn and decay of Sn to the excited states of Te
Limits on EC and ECEC processes in Sn and on
decay of Sn to the excited states of Te have
been obtained using a 380 cm HPGe detector and an external source
consisting of natural tin. A limit with 90% C.L. on the Sn half-life of
y for the ECEC(0) transition to the excited
state in Cd (1871.0 keV) has been established. This transition is
discussed in the context of a possible enhancement of the decay rate by several
orders of magnitude given that the ECEC process is nearly degenerate
with an excited state in the daughter nuclide. Prospects for investigating such
a process in future experiments are discussed. The decay
limits for Sn to the excited states of Te were obtained on the
level of y at the 90% C.L.Comment: 17 pages, 5 figure
Measurement of double beta decay of ¹⁰⁰Mo to excited states in the NEMO 3 experiment
The double beta decay of ¹⁰⁰Mo to the 0_{1}^{+} and 2_{1}^{+} excited states of ¹⁰⁰Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of ¹⁰⁰Mo to the excited 0_{1}^{+} state is measured to be T_{1/2}^{2v} = [5.7_{-0.9}^{+1.3} (stat.) ± 0.8 (syst.)] x 10²⁰ y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0_{1}^{+} state has been found. The corresponding half-life limit is T_{1/2}^{0v} (0⁺→0_{1}^{+}) > 8.9 x 10²² y (at 90% C.L.). The search for the double beta decay to the 2_{1}^{+} excited state has allowed the determination of limits on the half-life for the two neutrino mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.1 x 10²¹ y (at 90% C.L.) and for the neutrinoless mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.6 x 10²³ y (at 90% C.L.)
Measurement of Th-232(n,5n gamma) cross sections from 29 to 42 MeV
The excitation function of the reaction Th-232(n,5n gamma)Th-228 from 29 to 42 MeV has been measured for the first time at the quasi-monoenergetic neutron beam of the UCL cyclotron CYCLONE employing the Li-7(p,n) source reaction. Taking advantage of the good energy resolution of the planar High Purity Germanium (HPGe) detectors, prompt gamma-ray spectroscopy was used to detect the gamma rays resulting from the decay of excited states of nuclei created by the (n,xn) reactions. The neutron beam was characterized by a combination of time of flight measurements carried out using a liquid scintillation detector and a U-238 fission ionization chamber and fluence measurements carried Out using a proton recoil telescope. The preliminary results are compared with calculations performed using the TALYS-0.72 code.International Conference on Nuclear Data for Science and Technology, Proceedings, Apr 22-27, 2007, Nice, Franc
Probing New Physics Models of Neutrinoless Double Beta Decay with SuperNEMO
The possibility to probe new physics scenarios of light Majorana neutrino
exchange and right-handed currents at the planned next generation neutrinoless
double beta decay experiment SuperNEMO is discussed. Its ability to study
different isotopes and track the outgoing electrons provides the means to
discriminate different underlying mechanisms for the neutrinoless double beta
decay by measuring the decay half-life and the electron angular and energy
distributions.Comment: 17 pages, 14 figures, to be published in E.P.J.
Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils
The development of BiPo detectors is dedicated to the measurement of
extremely high radiopurity in Tl and Bi for the SuperNEMO
double beta decay source foils. A modular prototype, called BiPo-1, with 0.8
of sensitive surface area, has been running in the Modane Underground
Laboratory since February, 2008. The goal of BiPo-1 is to measure the different
components of the background and in particular the surface radiopurity of the
plastic scintillators that make up the detector. The first phase of data
collection has been dedicated to the measurement of the radiopurity in
Tl. After more than one year of background measurement, a surface
activity of the scintillators of (Tl) 1.5
Bq/m is reported here. Given this level of background, a larger BiPo
detector having 12 m of active surface area, is able to qualify the
radiopurity of the SuperNEMO selenium double beta decay foils with the required
sensitivity of (Tl) 2 Bq/kg (90% C.L.) with a six
month measurement.Comment: 24 pages, submitted to N.I.M.
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