(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES ...will perform a calorimetric measurement of the energy released in the decay of ...Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted ...Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Fusion for Energy (F4E), the European Domestic Agency for the International Thermonuclear Experimental Reactor (ITER) is responsible for the manufacturing, test and delivery of 5 out of 6 Poloidal ...Field Coils of ITER. F4E has currently delivered 4 coils: PF2, PF4, PF5 and PF6, the last two are installed in the Tokamak pit in temporary positions while PF2 and PF4 are stored awaiting the Tokamak torus completion. At the PF coils manufacturing production site in Cadarache, France, few meters away from the ITER Tokamak assembly building, F4E is currently finalizing the manufacturing and testing of the largest coil: PF3, with 24 m diameter and a weight of 384 t, approaching to the end of an endeavor that started back in 2013. This article describes all electrical tests the PF coils underwent to meet the ITER technical requirements during their lengthy manufacturing process, and which lasted several years. Tests performed at key points of the manufacturing process avoided discovering non-conformities at later stages that could otherwise become critical for the project accomplition. The main electrical tests consisted of high voltage DC/AC, partial discharge tests, and local and global Paschen tests. The experimental setups and procedures are presented and discussed in more detail. We also summarize the acceptance test results for the finalized coils i.e., 80 K forced flow pressure drop testing, leak tightness in vacuum before, during and after the thermal cycle to 80 K.
In the last years organic scintillators have been largely investigated in order to achieve high light yield together with good time response. Pure organic compound with high quality crystalline ...structure can achieve both this goals. Among a large type of organic compound, para-terphenyl (C18H14) have proven to have practical applications as detector medium for particle physics. In this work, the characterization of different sizes high quality mono-crystal p-terphenyl samples is presented. The optical and scintillation properties (emission spectrum, light yield, attenuation length, and decay time) are investigated. Coupling a Silicon PhotoMultiplier-based readout system to the crystal, a small prototype for a high resolution TOF detector was built; the preliminary results, obtained on a 20×30×3mm3 sample, with dual-side read-out (Hamamatsu S10931-050P SiPMs) and irradiated with 90Sr source, show a time resolution of 35ps.
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4.
A high resolution Timing Counter for the MEG II experiment De Gerone, M.; Bevilacqua, A.; Biasotti, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Volume:
824
Journal Article
Peer reviewed
The development of a Timing Counter detector designed for the MEGII upgrade of the MEG experiment, which strives to improve the sensitivity on the μ+→e+γ decay of an order of magnitude, is presented. ...It is based on two sets of counters (sectors) arranged on a semi-cylindrical structure; each sector consists of 256 counters. Each counter consists of tile of fast scintillator with a dual-side read-out based on SiPM arrays in series connection. The high granularity has two advantages: optimized size for achieving high resolution (75ps) for the single counter, and a signal e+ crosses several counters, so that resolution improves by averaging multiple time measurements. A prototype has been built and tested both in BTF and PSI facilities in order to prove the multi-hit scheme in MEG-like beam conditions. A 35ps resolution with eight hits has been obtained with a e+ beam at 100kHz. The first sector will be tested in the MEG II pre-engineering run planned at the end of 2015.
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The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from ...AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximise the pixel resolution. Gain measurements have also been performed.
•Characterisation of SiPMs for MEG-II Timing Counter is illustrated.•SiPMs breakdown voltage and gain measurement are reported.•The criterion for the choice of each single pixel SiPMs is explained.
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The main goal in the HOLMES experiment is the neutrino mass measurement using an array of 1000micro-calorimeters with standard metallic absorber. A good isotope for such measurement is the 163Ho, ...those isotopes embedded in the metallic absorber will be 1011–1013. Since 163Ho is not available in nature, a dedicated process must be set up to produce the amount needed for this neutrino mass experiment. The process with the highest born-up cross-section is the neutron irradiation of Er2O3 enriched in 162Er: 162Er(n,γ)163Er →163Ho+νe, where the decay is an EC with half-life of about 75min and the (n,γ) is about 20barns for thermal neutron. After the neutron irradiation in the oxide powder there are several radioactive isotopes which are potentially disturbing because of the background that they cause below 5keV. The chemical separation of holmium from the irradiation enriched Er2O3 powder is therefore mandatory and will be performed by means of ion exchange chromatography. On the end of those processes the oxide powder enriched in 162Er will have the 163Ho isotope number required. The holmium chemical state influences the end point of the EC spectrum, in order to avoid such effect it is necessary to embed in the absorber only the metallic isotope. Reduction and distillation technique allowed us to obtain a pure metallic holmium, starting from natural oxide holmium. This technique will be applied on the irradiated oxide powder to obtain the metallic 163Ho, ready to be embedded in the micro-calorimeter absorber.
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7.
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, Volume:
824
Journal Article
Peer reviewed
Open access
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.
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Preliminary Results of the MARE Experiment Ferri, E.; Bagliani, D.; Biassotti, M. ...
Journal of low temperature physics,
09/2014, Volume:
176, Issue:
5-6
Journal Article
Peer reviewed
The microcalorimeter array for a rhenium experiment (MARE) project aims at the direct and calorimetric measurement of the electron neutrino mass with sub-eV sensitivity. The design is based on large ...arrays of thermal detectors to study the beta decay of
187
Re and the electron capture of
163
Ho. One of the activities of the project, MARE 1 in Milan, has started in Milan using one array of 6
×
6 silicon implanted thermistors equipped with AgReO
4
absorbers. The purposes of MARE 1 in Milan are to achieve a sensitivity on the neutrino mass of a few eV and to investigate the systematics of
187
Re neutrino mass measurements, focusing on those caused by the beta environmental fine structure and the beta spectrum theoretical shape. In parallel, the MARE collaboration is performing an R&D work for producing absorbers embedded with radioactive metal
163
Ho. We report here the status of MARE using Re as beta source and the preliminary results obtained with
163
Ho.
The final results of the search for the lepton flavour violating decay
μ
+
→
e
+
γ
based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013 and ...totalling
7.5
×
10
14
stopped muons on target are presented. No significant excess of events is observed in the dataset with respect to the expected background and a new upper limit on the branching ratio of this decay of
B
(
μ
+
→
e
+
γ
)
<
4.2
×
10
-
13
(90 % confidence level) is established, which represents the most stringent limit on the existence of this decay to date.
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Low temperature detectors operated at about 0.1K have achieved excellent spectral performances in the soft X-rays, becoming appealing for new challenging measurements with space missions in ...Astrophysics. In order to exploit their full sensitivity, it is necessary to minimize the background signals generated by the cosmic rays, i.e., high energy protons and light nuclei, that leave sizable amounts of energy in the same spectral window of the astrophysics signals. Detectors for GeV protons and nuclei operating few millimeters from the X-ray detector at 0.1K can act as anti-coincidence to disentangle the fake signal of cosmics. Fast and large detectors are designed and fabricated. These operate by mixing the fast a-thermal phonon signal with the slow diffusive thermal ones. A greater uniformity in the response should be obtained using large shaped superconducting aluminium films that acts as phonon collectors: the quasi-particles created by high energy phonons diffuse along the film toward a small Ir TES sensor giving out to a fast rise time. Here we present the measurement of an operating prototype of a superconducting anticoincidence detector for the proposed space mission ATHENA+.
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