Search results for "Spall"
showing 10 items of 69 documents
Coherent elastic neutrino-nucleus scattering at the European Spallation Source
2020
The European Spallation Source (ESS), presently well on its way to completion, will soon provide the most intense neutron beams for multi-disciplinary science. Fortuitously, it will also generate the largest pulsed neutrino flux suitable for the detection of Coherent Elastic Neutrino-Nucleus Scattering (CE$\nu$NS), a process recently measured for the first time at ORNL's Spallation Neutron Source. We describe innovative detector technologies maximally able to profit from the order-of-magnitude increase in neutrino flux provided by the ESS, along with their sensitivity to a rich particle physics phenomenology accessible through high-statistics, precision CE$\nu$NS measurements.
Mitigation of backgrounds from cosmogenic 137 Xe in xenon gas experiments using 3 He neutron capture
2020
[EN] Xe-136 is used as the target medium for many experiments searching for 0 nu beta beta. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of Xe-137 created by the capture of neutrons on Xe-136. This isotope decays via beta decay with a half-life of 3.8 min and a Q(beta) of similar to 4.16 MeV. This work proposes and explores the concept of adding a small percentage of He-3 to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we f…
Measurements of Spallation Residues Using Inverse Kinematics at GSI
2002
The production cross sections and the kinematical properties of primary residual nuclei have been studied in reactions 197Au + p, 208Pb + p, d, 238U + p, d, and 238U + 208Pb at energies around 1 A GeV. The measured kinematical properties of the residues were also used to disentangle the relevant reaction mechanisms, spallation-evaporation and spallation-fission. The fragment separator FRS at GSI, Darmstadt, was used to separate and identify the reaction products. The measured quantities are important for the design and planning of future radioactive-beam facilities and accelerator-driven systems.
Study of the Ti44(α,p)V47 reaction and implications for core collapse supernovae
2014
The underlying physics triggering core collapse supernovae is not fully understood but observations of material ejected during such events helps to solve this puzzle. In particular, several satellite based γ-ray observations of the isotope 44Ti have been reported recently. Conveniently, the amount of this isotope in stellar ejecta is thought to depend critically on the explosion mechanism. The most influential reaction to the amount of 44Ti in supernovae is Ti44(α,p)V47. Here we report on a direct study of this reaction conducted at the REX-ISOLDE facility, CERN. The experiment was performed with a 44Ti beam at Elab = 2.16MeV/u, corresponding to an energy distribution, for reacting α-partic…
The new neutron-rich isotope228Rn
1989
2 pages, 1 table, 2 figures.-- PACS nrs.: 23.90.+w; 27.90.+b.-- Section: Short Notes.
<title>Studies of the activation background in CsI(Tl) detectors</title>
1993
CsI scintillation crystals are widely used as detection in (gamma) -ray astronomy observations. In the MeV energy region, one of the most important background sources in CsI is the (beta) decays induced in the crystal by cosmic ray protons and their secondaries. One recent idea for reducing this background is to use discrete detector arrays to reject the large amount of localized (beta) decay events. Two experiments were carried out with 1 cm3 CsI crystals bombarded with energetic proton beams and fast/thermal neutrons, with the aim of evaluating the effectiveness of this method in pixelated (1 cm3) CsI detectors. The ratio of the number of decays resulting in single site and multiple site …
He-3 spin filter for neutrons
2005
The strongly spin-dependent absorption of neutrons in nuclear spin-polarized (3)He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This paper gives a report on the neutron spin filter (NSF) development program at Mainz. The polarization technique is based on direct optical pumping of metastable (3)He atoms combined with a polarization preserving mechanical compression of the gas up to a pressure of several bar, necessary to run a NSF. The concept of a remote type of operation using detachable NSF cells is presented which requires long nuclear spin relaxation times of order 100 hours. A sh…
Polycyclic aromatic hydrocarbons (PAHs) in the polychaete Sabella spallanzanii, as a reliable bioindicator, by GCMS
2012
Every year 230.000 tons of PAHs enter the marine environment, resulting ubiquitously distributed worldwide. These compounds are aromatic molecules of special concern because of their toxic and carcinogenic properties. As a consequence of their hydrophobic nature, in aquatic environments, PAHs rapidly tend to associate with particulate matter and sediments represent the most important reservoir. In the present study the level of PAHs in the sessile filter-feeder polychaete Sabella spallanzanii was assessed. In particular, the concentration of PAHs was determined in polychaetes (body and tube) collected from three Sicilian areas, subject to different anthropic pressure. A transplanting experi…
Gamma Ray Spectrum from Thermal Neutron Capture on Gadolinium-157
2018
International audience; We have measured the |$\gamma$|-ray energy spectrum from the thermal neutron capture, |${}^{157}$|Gd|$(n,\gamma)$|, on an enriched |$^{157}$|Gd target (Gd|$_{2}$|O|$_{3}$|) in the energy range from 0.11 MeV up to about 8 MeV. The target was placed inside the germanium spectrometer of the ANNRI detector at J-PARC and exposed to a neutron beam from the Japan Spallation Neutron Source (JSNS). Radioactive sources (|$^{60}$|Co, |$^{137}$|Cs, and |$^{152}$|Eu) and the |$^{35}$|Cl(|$n$|,|$\gamma$|) reaction were used to determine the spectrometer‘s detection efficiency for |$\gamma$| rays at energies from 0.3 to 8.5 MeV. Using a Geant4-based Monte Carlo simulation of …
Internal geometry and coolant choices for solid high power neutron spallation targets
2014
Abstract The next generation of neutron spallation sources envisages high power proton beam interaction with a heavy metal target. Solid targets have potentially higher spallation efficiency due to the possibility to use metals with higher density than used in liquid metal targets, but to realize this potential the solid fraction must be high enough. As the power released in the form of heat can reach several MW in the target volume of typically 10 l, target cooling can be a serious challenge. Heat evacuation efficiency for different solid fraction geometries at high power is analyzed for different coolant options (helium, water and gallium) using empirical correlations for friction factors…