41 research outputs found
Absence of low-temperature dependence of the decay of 7Be and 198Au in metallic hosts
The electron-capture (EC) decay rate of 7Be in metallic Cu host and the
beta-decay rate of 198Au in the host alloy Al-Au have been measured
simultaneously at several temperatures, ranging from 0.350 K to 293 K. No
difference of the half-life of 198Au between 12.5 K and 293 K is observed to a
precision of 0.1%. By utilizing the special characteristics of our
double-source assembly, possible geometrical effects that influence the
individual rates could be eliminated. The ratio of 7Be to 198Au activity thus
obtained also remains constant for this temperatures range to the experimental
precision of 0.15(0.16)%. The resulting null temperature dependence is
discussed in terms of the inadequacy of the often-used Debye-Huckel model for
such measurements.Comment: Four pages, three figures. Accepted for publication in Phys. Rev. C
(Rapd Communications
A New Precision Measurement of the 3He(4He,gamma)7Be Cross section
The 3He(4He,gamma)7Be reaction plays an important role in determining the
high energy solar neutrino flux and in understanding the abundances of
primordial 7Li. The present paper reports a new precision measurement of the
cross sections of this direct capture reaction, determined by measuring the
ensuing 7Be activity in the region of Ec.m.=400 keV to 950 keV. Various recent
theoretical fits to our data result in a consistent extrapolated value of
S34(0)=0.53(2)(1).Comment: 10 pages 3 figure
A New Precision Measurement of the 7Be(p,gamma)8B Cross section with an Implanted 7Be Target
The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar
neutrino fluxes. We report on a new precision measurement of the cross section
of this reaction, following our previous experiment with an implanted 7Be
target, a raster scanned beam and the elimination of the backscattering loss.
The new measurement incorporates a more abundant 7Be target and a number of
improvements in design and procedure. The point at Elab=991 keV was measured
several times under varying conditions, yielding a value of S17(Ec.m. =850 keV)
= 24.0(5) eV b. Measurements were carried out at lower energies as well. Due to
the precise knowledge of the implanted 7Be density profile it was possible to
reconstitute both the off- and on resonance parts of the cross section and to
obtain from the entire set of measurements an extrapolated value of
S17(0)=21.2(7) eV b.Comment: 4 Pages, 3 Figure
The SPIRAL2 control system progress towards the commissioning phase
MOCOAAB03, http://accelconf.web.cern.ch/AccelConf/ICALEPCS2013/papers/mocoaab03.pdfInternational audienceThe commissioning of the first phase of the Spiral2 Radioactive Ion Beams facility at Ganil will soon start, so requiring the control system components to be delivered in time. Yet, parts of the system were validated during preliminary tests performed with ions and deuterons beams at low energy. The control system development results from the collaboration between Ganil, CEA-IRFU, CNRS-IPHC laboratories, using appropriate tools and approach. Based on Epics, the control system follows a classical architecture. At the lowest level, Modbus/TCP protocol is considered as a field bus. Then, equipment are handled by IOCs (soft or VME/VxWorks) with a software standardized interface between IOCs and clients applications on top. This last upper layer consists of Epics standard tools, CSS/BOY user interfaces within the socalled CSSop Spiral2 context suited for operation and, for machine tunings, high level applications implemented by Java programs developed within a Spiral2 framework derived from the open-Xal one. Databases are used for equipment data and alarms archiving, to configure equipment and to manage the machine lattice and beam settings. A global overview of the system is therefore here proposed
A Small but Efficient Collaboration for the Spiral2 Control System Development
http://accelconf.web.cern.ch/AccelConf/ICALEPCS2013/papers/tucobab01.pdfThe Spiral2 radioactive ion beam facility to be commissioned in 2014 at Ganil (Caen) is built within international collaborations. This also concerns the control system development shared by three laboratories: Ganil has to coordinate the control and automated systems work packages, CEA/IRFU is in charge of the "injector" (sources and low energy beam lines) and the LLRF, CNRS/IPHC provides the emittancemeters and a beam diagnostics platform. Besides the technology Epics based, this collaboration, although being handled with a few people, nevertheless requires an appropriate and tight organization to reach the objectives given by the project. This contribution describes how, started in 2006, the collaboration for controls has been managed both from the technological point of view and the organizational one, taking into account not only the previous experience, technical background or skill of each partner, but also their existing working practices and "cultural" approaches. A first feedback comes from successful beam tests carried out at Saclay and Grenoble; a next challenge is the migration to operation, Ganil having to run Spiral2 as the other members are moving to new projects
Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies
3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3â8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor
Exposure assessment of radon in the drinking water supplies: a descriptive study in Palestine
<p>Abstract</p> <p>Background</p> <p>Radon gas is considered as a main risk factor for lung cancer and found naturally in rock, soil, and water. The objective of this study was to determine the radon level in the drinking water sources in Nablus city in order to set up a sound policy on water management in Palestine.</p> <p>Methods</p> <p>This was a descriptive study carried out in two phases with a random sampling technique in the second phase. Primarily, samples were taken from 4 wells and 5 springs that supplied Nablus city residents. For each source, 3 samples were taken and each was analyzed in 4 cycles by RAD 7 device manufactured by Durridge Company. Secondly, from the seven regions of the Nablus city, three samples were taken from the residential tap water of each region. Regarding the old city, ten samples were taken. Finally, the mean radon concentration value for each source was calculated.</p> <p>Results</p> <p>The mean (range) concentration of radon in the main sources were 6.9 (1.5-23.4) Becquerel/liter (Bq/L). Separately, springs and wells' means were 4.6 Bq/L and 9.5 Bq/L; respectively. For the residential tap water in the 7 regions, the results of the mean (range) concentration values were found to be 1.0 (0.9-1.3) Bq/L. For the old city, the mean (range) concentration values were 2.3 (0.9-3.9) Bq/L.</p> <p>Conclusions</p> <p>Except for Al-Badan well, radon concentrations in the wells and springs were below the United State Environmental Protection Agency maximum contaminated level (U.S EPA MCL). The level was much lower for tap water. Although the concentration of radon in the tap water of old city were below the MCL, it was higher than other regions in the city. Preventive measures and population awareness on radon's exposure are recommended.</p