Status of the HOLMES detector development Nucciotti, A.; Alpert, B.; Becker, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
Odprti dostop
HOLMES is a new experiment to directly measure the neutrino mass with a sensitivity as low as 0.4eV. HOLMES will perform a calorimetric measurement of the energy released in the electron capture ...decay of 163Ho. HOLMES will deploy a large array of low temperature microcalorimeters with implanted 163Ho nuclei. HOLMES baseline detector is an array of 1000 microcalorimeters each with an implanted 163Ho activity of about 300 Bq, an energy resolution FWHM of about 1eV at the spectrum end-point (Q≈2.5 keV), and a time resolution of about 1μs. Matching these performances requires a careful optimization of all components, from the microcalorimeters to the signal processing algorithms. We outline here the project technical challenges and the present status of the development.
Measurement of the .sup.171Tm half-life Kajan, I; S. Pommé; Heinitz, S
Journal of radioanalytical and nuclear chemistry,
01/2022, Letnik:
331, Številka:
1
Journal Article
Recenzirano
The half-life of .sup.171Tm was measured by gamma-ray spectrometry, using the reference source method. The measured point-like source was prepared by homogenous mixing of .sup.44Ti with .sup.171Tm in ...order to obtain an identical detection geometry for both nuclides. The half-life of .sup.171Tm was determined by following the count-rate ratio between the gamma-ray emissions at 66.73 keV (.sup.171Tm) and 67.9/78.3 keV (.sup.44Ti). The measurement campaign consisted of 280 measurements acquired over a period of 449 days, corresponding to about 60% of the half-life value. The result for the .sup.171Tm half-life, 702.4 (70) d, is consistent with the currently recommended value, however the uncertainty assessment of the latter is poorly documented.
The accurate calculations of neutron-induced reaction cross sections are relevant for many nuclear applications. The photon strength functions and nuclear level densities are essential inputs for ...such calculations. These quantities for 235U are studied using the measurement of the gamma de-excitation cascades in radiative capture on 234U with the Total Absorption Calorimeter at n_TOF at CERN. This segmented 4π gamma calorimeter is designed to detect gamma rays emitted from the nucleus with high efficiency. This experiment provides information on gamma multiplicity and gamma spectra that can be compared with numerical simulations. The code DICEBOXC is used to simulate the gamma cascades while GEANT4 is used for the simulation of the interaction of these gammas with the TAC materials. Available models and their parameters are being tested using the present data. Some preliminary results of this ongoing study are presented and discussed.
A 10Be beam having intensities up to 3 enA has been accelerated at the Tandem of the Laboratori Nazionali del Sud in Catania. The used 10Be was chemically extracted from a proton irradiated graphite ...target used for muon production at the Paul Scherrer Institute. In order to maximise the extracted current using a minimum amount of isotope, several preparatory tests, needed to optimise the preparation of the Tandem sputter source cathodes, were performed. The acceleration tests and accelerated beam characteristics will be discussed and examples of beam use for nuclear structure investigations will be presented.
At the neutron time-of-flight facility n_TOF at CERN a new vertical beam line was constructed in 2014, in order to extend the experimental possibilities at this facility to an even wider range of ...challenging cross-section measurements of interest in astrophysics, nuclear technology and medical physics. The design of the beam line and the experimental hall was based on FLUKA Monte Carlo simulations, aiming at maximizing the neutron flux, reducing the beam halo and minimizing the background from neutrons interacting with the collimator or back-scattered in the beam dump.
The present paper gives an overview on the design of the beam line and the relevant elements and provides an outlook on the expected performance regarding the neutron beam intensity, shape and energy resolution, as well as the neutron and photon backgrounds.
This work presents the first direct measurement of the
Mo half-life. The measurement is a combination of high-resolution mass spectrometry for the determination of the
Mo concentration and liquid ...scintillation counting for determining the specific activity. A
Mo sample of high purity was obtained from proton irradiated niobium by chemical separation of molybdenum with a decontamination factor larger than 1.6 × 10
with respect to Nb. The half-life of
Mo was deduced to be 4839(63) years, which is more than 20% longer than the currently adopted value, whereas the relative uncertainty could be reduced by a factor of 15. The probability that the
Mo decays to the metastable state
Nb was determined to be 95.7(16)%. This value is a factor of 8 more precise than previous estimations. Due to the man-made production of
Mo in nuclear facilities, the result leads to significantly increased precision for modelling the low-level nuclear waste composition. The presented work demonstrates the importance of chemical separations in combination with state-of-the-art analysis techniques, which are inevitable for precise and accurate determinations of nuclear decay data.
This paper describes the production and chemical separation of the .sup.163 Ho isotope that will be used in several nuclear physics experiments aiming at measuring the neutrino mass as well as the ...neutron cross section of the .sup.163 Ho isotope. For this purpose, several batches of enriched .sup.162 Er have been irradiated at the Institut Laue-Langevin high flux reactor to finally produce 6 mg or 100 MBq of the desired .sup.163 Ho isotope. A portion of the Er/Ho mixture is then subjected to a sophisticated chemical separation involving ion exchange chromatography to isolate the Ho product from the Er target material. Before irradiation, a thorough analysis of the impurity content was performed and its implication on the produced nuclide inventory will be discussed.
PDF
