The PADME experiment, hosted at the Laboratori Nazionali di Frascati in Italy, is dedicated to the dark photon search. It looks for the reaction e+e−arrowA′γ, where A′ indicates the dark photon. The ...550MeV positrons beam that impinges on electrons, coming from an active diamond target, allows to scan A′ masses up to 23.7MeV. In this context, the segmented electromagnetic calorimeter plays a fundamental role, since it measures the final photon four-momentum. It consists of 616 BGO crystals displaced in a cylindrical shape of ≈29cm radius with a central square hole of 5 crystals side, to let Bremsstrahlung radiation pass, to limit the calorimeter trigger rate. Each crystal is read by a HZC XP1911 type B photomultipliers and their signal is digitised by means of a CAEN V1742 board, taking 1024 samples at 1GS/S. Here we report in detail the solutions adopted for the calorimeter together with the results obtained in tests performed on a small prototype and on single scintillating units.
The projected background for the CUORE experiment Alduino, C.; Avignone, F. T.; Azzolini, O. ...
European physical journal. C, Particles and fields,
08/2017, Letnik:
77, Številka:
8
Journal Article
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The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of
130
Te with an array of 988 TeO
2
bolometers operating at temperatures ...around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the
130
Te decay half-life of 9
×
10
25
years after 5 years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10
-
2
counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of
130
Te is expected.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The PADME beam line Monte Carlo simulation Bossi, F.; Branchini, P.; Buonomo, B. ...
The journal of high energy physics,
09/2022, Letnik:
2022, Številka:
9
Journal Article
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A
bstract
The PADME experiment at the DAΦNE Beam-Test Facility (BTF) of the INFN Laboratory of Frascati is designed to search for invisible decays of dark sector particles produced in ...electron-positron annihilation events with a positron beam and a thin fixed target, by measuring the missing mass of single-photon final states. The presence of backgrounds originating from beam halo particles can significantly reduce the sensitivity of the experiment. To thoroughly understand the origin of the beam background contribution, a detailed G
eant
4-based Monte Carlo simulation has been developed, containing a full description of the detector together with the beam line and its optical elements. This simulation allows the full interactions of each particle to be described, both during beam line transport and during detection, a possibility which represents an innovative way to obtain reliable background predictions.
We present the performances of a 330 g zinc molybdate (ZnMoO
4
) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double ...beta decay of
100
Mo. The energy resolution, evaluated at the 2615 keV
γ
-line of
208
Tl, is 6.3 keV FWHM. The internal radioactive contaminations of the ZnMoO
4
were evaluated as <6 μBq/kg (
228
Th) and 27±6 μBq/kg (
226
Ra). We also present the results of the
α
vs
β
/
γ
discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Neutrinoless double-beta (0vββ) decay is a hypothesized lepton-number-violating process that offers the only known means of asserting the possible Majorana nature of neutrino mass. The Cryogenic ...Underground Observatory for Rare Events (CUORE) is an upcoming experiment designed to search for 0vββ decay of sup.130Te using an array of 988 TeO.sub.2 crystal bolometers operated at 10 mK. The detector will contain 206 kg of sup.130Te and have an average energy resolution of 5 keV; the projected 0vββ decay half-life sensitivity after five years of livetime is 1.6 x 10.sup.26 γ at 1σ (9.5 x 10.sup.25 γ at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40-100 meV (50-130 meV). In this paper, we review the experimental techniques used in CUORE as well as its current status and anticipated physics reach.
CUORE, an array of 988 TeO
2
bolometers, is about to be one of the most sensitive experiments searching for neutrinoless double-beta decay. Its sensitivity could be further improved by removing the ...background from
α
radioactivity. A few years ago it was pointed out that the signal from
β
s can be tagged by detecting the emitted Cherenkov light, which is not produced by
α
s. In this paper we confirm this possibility. For the first time we measured the Cherenkov light emitted by a CUORE crystal, and found it to be 100 eV at the
Q
-value of the decay. To completely reject the
α
background, we compute that one needs light detectors with baseline noise below 20 eV RMS, a value which is 3–4 times smaller than the average noise of the bolometric light detectors we are using. We point out that an improved light detector technology must be developed to obtain TeO
2
bolometric experiments able to probe the inverted hierarchy of neutrino masses.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of Formula: see textSe. The matrix which embeds the ...source is an array of ZnSe crystals, where enriched Formula: see textSe is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3 % enriched Formula: see textSe metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of Formula: see textTh, Formula: see textU and Formula: see textU are respectively: Formula: see text61, Formula: see text110 and Formula: see text74 Formula: see textBq/kg at 90 % C.L. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the Formula: see textSe allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of Formula: see textSe to 0Formula: see text, 2Formula: see text and 2Formula: see text excited states of Formula: see textKr of 3.4Formula: see text10Formula: see text, 1.3Formula: see text10Formula: see text and 1.0Formula: see text10Formula: see text y, respectively, with a 90 % C.L.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose:
To evaluate the geometric and dosimetric accuracies of the CyberKnife Synchrony respiratory tracking system (RTS) and to validate a method for pretreatment patient-specific delivery quality ...assurance (DQA).
Methods:
An EasyCube phantom was mounted on the ExacTrac gating phantom, which can move along the superior–inferior (SI) axis of a patient to simulate a moving target. The authors compared dynamic and static measurements. For each case, a Gafchromic EBT3 film was positioned between two slabs of the EasyCube, while a PinPoint ionization chamber was placed in the appropriate space. There were three steps to their evaluation: (1) the field size, the penumbra, and the symmetry of six secondary collimators were measured along the two main orthogonal axes. Dynamic measurements with deliberately simulated errors were also taken. (2) The delivered dose distributions (from step 1) were compared with the planned ones, using the gamma analysis method. The local gamma passing rates were evaluated using three acceptance criteria: 3% local dose difference (LDD)/3 mm, 2%LDD/2 mm, and 3%LDD/1 mm. (3) The DQA plans for six clinical patients were irradiated in different dynamic conditions, to give a total of 19 cases. The measured and planned dose distributions were evaluated with the same gamma-index criteria used in step 2 and the measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber.
Results:
(1) A very slight enlargement of the field size and of the penumbra was observed in the SI direction (on average <1 mm), in line with the overall average CyberKnife system error for tracking treatments. (2) Comparison between the planned and the correctly delivered dose distributions confirmed the dosimetric accuracy of the RTS for simple plans. The multicriteria gamma analysis was able to detect the simulated errors, proving the robustness of their method of analysis. (3) All of the DQA clinical plans passed the tests, both in static and dynamic conditions. No statistically significant differences were found between static and dynamic cases, confirming the high degree of accuracy of the Synchrony RTS.
Conclusions:
The presented methods and measurements verified the mechanical and dosimetric accuracy of the Synchrony RTS. Their method confirms the fact that the RTS, if used properly, is able to treat a moving target with great precision. By combining PinPoint ion chamber, EBT3 films, and gamma evaluation of dose distributions, their DQA method robustly validated the effectiveness of CyberKnife and Synchrony system.
The PADME experiment will search for the <inline-formula> <tex-math notation="LaTeX">e^{+} e^{-} \rightarrow \gamma A^{\prime } </tex-math></inline-formula> process in a positron-on-target ...experiment, assuming a decay of the <inline-formula> <tex-math notation="LaTeX">A^{\prime } </tex-math></inline-formula> into invisible particles of the hidden sector. The 550-MeV positron beam of the DA<inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula>NE beam-test facility (BTF), at Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, will be used. The suppression of the background, due to bremsstrahlung emission from the beam positrons, requires highly efficient charged-particle detectors with optimized geometry. A fine-grained plastic scintillator veto composed of three stations operating in vacuum is proposed. Two stations, placed inside a dipole magnet with 0.6-T magnetic field, will also provide momentum measurement at the percent level. Different prototypes for the design of the detector elements, the photosensor, and the front-end electronics were studied with single electron beam at the DA<inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula>NE BTF to choose the optimal technologies and construction solutions. PADME is currently under construction, and it is planned to begin data collection in 2018. The design of the charged-particle vetoes and the test beam performance of the prototypes are reviewed.
A possible solution to the Dark Matter problem postulates that it interacts with Standard Model particles through a new force mediated by a "portal". If the new force has a U(1) gauge structure, the ..."portal" is a massive photon-like vector particle, called dark photon or A'. The PADME experiment at the DAΦNE Beam-Test Facility (BTF) in Frascati is designed to detect dark photons produced in positron on fixed target annihilations decaying to dark matter (e+e-→γA′) by measuring the final state missing mass. One of the key roles of the experiment will be played by the electromagnetic calorimeter, which will be used to measure the properties of the final state recoil γ. The calorimeter will be composed by 616 21×21×230 mm3 BGO crystals oriented with the long axis parallel to the beam direction and disposed in a roughly circular shape with a central hole to avoid the pile up due to the large number of low angle Bremsstrahlung photons. The total energy and position of the electromagnetic shower generated by a photon impacting on the calorimeter can be reconstructed by collecting the energy deposits in the cluster of crystals interested by the shower. In PADME we are testing two different clustering algorithms, PADME-Radius and PADME-Island, based on two complementary strategies. In this paper we will describe the two algorithms, with the respective implementations, and report on the results obtained with them at the PADME energy scale (< 1 GeV), both with a GEANT4 based simulation and with an existing 5×5 matrix of BGO crystals tested at the DAΦNE BTF.
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