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Signal map for the front central cell generated by a muon beam parallel to the prototype main axis. The X and Y coordinates are given by the DWCs, whereas the color scale represents the energy deposited inside the prototype in ADC channels.
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The LHCb experiment is one of the four main particle detectors located at the Large Hadron Collider. After the High-Luminosity upgrade of the accelerator, the expected radiation dose faced by the LHCb electromagnetic calorimeter will reach peak values of 1 MGy in the centremost part, an amount not tolerable by the currently-employed shashlik techno...
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... Muon beam parallel to the prototype axis: At first, the prototype was placed with its main axis parallel to the beam pipe in order to assess the uniformity of the response on the orthogonal plane. In Fig. 6 the signal map for the front central GAGG cell is shown, where the coordinates of the particle are determined by the third DWC, the one closest to Fig. 7. Maps of the measured signal for the front cells before (a) and after (b) calibration, selecting only events above 10 GeV. The particle position is given by the DWCs. It can be seen ...
Context 2
... series of measurements with electron beams at 20 GeV was performed. Fig. 6 demonstrates how, in case of particles at small incidence angles, the signal produced is heavily dependent on the entrance point at the prototype surface: a MIP hitting a fibre produces a clear signal, much stronger than hitting the absorber. Such phenomenon, although mitigated by the transverse development of the cascade in case of ...
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Scintillating bolometer is a powerful tool to search neutrinoless double beta decay. We established a large scintillating bolometer using a 312 g CaF 2 (Eu) crystal with a readout technology of metallic magnetic calorimeters. A set of successful measurements were carried out for simultaneous detection for heat and light signals at 10-40 mK in an ab...
Citations
... The evaluation of different SpaCal module prototypes has been conducted through test beams at DESY and SPS, covering energy ranges of 1 to 5 GeV and 20 to 100 GeV, respectively [12]. In the subsequent discussion, we will not only address the performance in terms of energy resolution, considered the most pertinent parameter for LS3 enhancement, but also delve into the timing capability to demonstrate the alignment of SpaCal technology with the given requirements for Upgrade II. ...
The aim of the LHCb Upgrade II is to be able to operate at a luminosity of 1.5×10 ³⁴ cm ⁻² s ⁻¹ to collect a data set of 300 fb ⁻¹ . The required substantial modifications of the current LHCb electromagnetic calorimeter due to high radiation doses in the central region and increased particle densities are referred to as LHCb ECAL Upgrade II. A consolidation of the ECAL already during the long shutdown 3 will reduce the occupancy and mitigate the effects of substantial ageing in the central region after Run 3. Several scintillating sampling ECAL technologies are being investigated in an ongoing R&D campaign: Spaghetti Calorimeter (SpaCal) with garnet scintillating crystals and tungsten absorber, SpaCal with scintillating plastic fibres and tungsten or lead absorber, and Shashlik with polystyrene tiles, lead absorber and fast WLS fibres. Timing capabilities with tens of picoseconds precision for neutral electromagnetic particles and increased granularity with a denser absorber in the central region are needed for pile-up mitigation. Time resolutions of better than 20 ps at high energy were observed in test beam measurements of prototype SpaCal and Shashlik modules. Energy resolutions with sampling contributions of about 10%/√ E , in line with the requirements, were observed.
... For neutron rejection in addition the calorimeter shower properties and the time of arrival can be explored. It can be shown that the required background reduction is achievable with existing detector (calorimeter) technologies: time resolution 1 of ∼Oð10-100Þ ps [49][50][51], energy resolution of a few percent and finally, position and angular resolutions of ∼Oð100Þ μm and ∼Oð100Þ mrad respectively [49,[51][52][53]. We note that even a subset of these specifications is sufficient to meet our minimal requirements for the search. ...
... For neutron rejection in addition the calorimeter shower properties and the time of arrival can be explored. It can be shown that the required background reduction is achievable with existing detector (calorimeter) technologies: time resolution 1 of ∼Oð10-100Þ ps [49][50][51], energy resolution of a few percent and finally, position and angular resolutions of ∼Oð100Þ μm and ∼Oð100Þ mrad respectively [49,[51][52][53]. We note that even a subset of these specifications is sufficient to meet our minimal requirements for the search. ...
We propose a novel way to search for feebly interacting massive particles, exploiting two properties of systems involving collisions between high energy electrons and intense laser pulses. The first property is that the electron-laser collision results in a large flux of hard photons, as the laser behaves effectively as a thick medium. The second property is that the emitted photons free-stream inside the laser and thus for them the laser behaves effectively as a very thin medium. Combining these two features implies that the electron-intense-laser collision is an apparatus, which can efficiently convert O(10 GeV) electrons to a large flux of hard, collinear photons. The photons are directed onto a solid dump in which feebly interacting massive particles may be produced. With the much smaller backgrounds induced by the photon beam compared to those expected in electron- or proton-beam dump experiments and combined with a relatively shorter dump used here, the sensitivity to short lifetimes is unparalleled. We denote this novel apparatus as “optical dump” or NPOD (new physics search with optical dump). The proposed LUXE experiment at the European XFEL has all the basic required ingredients to realize this experimental concept for the first time. Moreover, the NPOD extension of LUXE is essentially parasitic to the main experiment and thus, practically it does not have any bearing on its main program. We discuss how the NPOD concept can be realized in practice by adding a detector after the last physical dump of the experiment to reconstruct the two-photon decay of a new spin-0 particle. We show that even with a relatively short dump, the search can still be background-free. Remarkably, even with a few days of data taking with a 40 TW laser corresponding to its initial run, LUXE-NPOD will be able to probe an uncharted territory of models with pseudoscalars and scalars. Furthermore, with a 350 TW laser of the main run, LUXE-NPOD will have a unique reach for these models. In particular it can probe natural scalar theories for masses above 100 MeV. We note that the new NPOD concept may be ported to other existing or future facilities worldwide, including, e.g., future lepton colliders.
... This paper studies a SPACAL with radiation-hard crystal fibres and tungsten absorber. Proof of concepts of this technology obtained promising results in the past years [6,7], but for the first time a novel prototype was assembled with pure tungsten absorber, garnet crystal fibres, and photomultipliers developed for picosecond timing. It was tested in the TB24 area of the DESY II testbeam facility with 1 to 5 GeV electron beams [8] Pictures of the Tungsten-Crystal SPACAL prototype without readout. ...
... Therefore, the back section was calibrated stand-alone, i.e. removing the front one, being sufficiently deep to achieve a reasonable containment of 3 GeV electron showers. Selecting only events hitting in a 20 × 20 mm 2 square in the centre of the back section, a set of 9 calibration coefficients for the back cells was found by minimising the residuals [7]: ...
A spaghetti calorimeter (SPACAL) prototype with scintillating crystal fibres was assembled and tested with electron beams of energy from 1 to 5 GeV. The prototype comprised radiation-hard Cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) and Y3Al5O12 (YAG:Ce) embedded in a pure tungsten absorber. The energy resolution was studied as a function of the incidence angle of the beam and found to be of the order of 10%/E⊕1%, in line with the LHCb Shashlik technology. The time resolution was measured with metal channel dynode photomultipliers placed in contact with the fibres or coupled via a light guide, additionally testing an optical tape to glue the components. Time resolution of a few tens of picosecond was achieved for all the energies reaching down to (18.5 ± 0.2) ps at 5 GeV.
... Nowadays, both the academic and industrial laboratories are focusing on the development and optimization of scintillation materials to fulfil increasingly demanding requirements of high energy physics (HEP) experiments. One of the most attractive potential applications for scintillators is the upcoming upgrade of LHCb experiment electromagnetic calorimeter [1]. Given the large volume of scintillators needed for HEP applications, in addition to high radiation hardness, fast scintillation response and reasonable light yield, the price is a factor of critical importance. ...
In this work we study the technological limits in the industrial scale growth of YAG:Ce by Czochralski method in hydrogen-reducing atmosphere to speed-up its scintillation response using heavy codoping by magnesium. We present correlated experiments to characterize luminescence and scintillation properties focusing on light yield, scintillation decay incl. its rise time, and afterglow, and their dependence on magnesium content in the crystals. We show that an optimum amount of magnesium in combination with thermal treatment significantly improve the light yield, decrease afterglow and accelerate scintillation decay and its rise time.
... This paper studies a SPACAL with radiation-hard crystal fibres and tungsten absorber. Proof of concepts of this technology obtained promising results in the past years [6,7], but for the first time a novel prototype was assembled with pure tungsten absorber, garnet crystal fibres, and photomultipliers developed for picosecond timing. It was tested at the DESY II test beam facility with 1 to 5 GeV electron beams [8], measuring the energy resolution at different incidence angles of the beam and studying the time resolution with particular emphasis on the role of optical coupling. ...
... Afterwards, the front section was removed and the same procedure was repeated for the back section. Then, by selecting only events hitting in a 20×20 mm 2 square in the centre of the back section, a set of 9 calibration coefficients c j for the back cells was found by minimising the residuals [17,7]: ...
A spaghetti calorimeter (SPACAL) prototype with scintillating crystal fibres was assembled and tested with electron beams of energy from 1 to 5 GeV. The prototype comprised radiation-hard Cerium-doped Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG:Ce) and Y$_3$Al$_5$O$_{12}$ (YAG:Ce) embedded in a pure tungsten absorber. The energy resolution was studied as a function of the incidence angle of the beam and found to be of the order of $10\% / \sqrt{E} \oplus1\%$, in line with the LHCb Shashlik technology. The time resolution was measured with metal channel dynodes photomultipliers placed in contact with the fibres or coupled via a light guide, additionally testing an optical tape to glue the components. Time resolution of a few tens of picosecond was achieved for all the energies reaching down to (18.5 $\pm$ 0.2) ps at 5 GeV.
... Nowadays, properties of a variety of garnet structure crystalline scintillators doped with rare earth ions are well studied and the materials are considered to be possible candidates for future scintillator-based detectors in highenergy physics experiments [1][2][3][4]. The brightest scintillations were obtained in compositionally disordered crystals having a mixture of Al and Ga in the matrix and a partial substitution of the rare earth cation Gd with Y: Y3Al2Ga3O12 (YAGG), Gd3Al2Ga3O12 (GAGG), (Gd, Y)3(Al, Ga)5O12 [5][6][7][8][9][10]. ...
The scintillation properties and radiation hardness of undoped and Ce doped YAG crystals, which were grown from tungsten crucibles in the Ar + CO atmosphere and annealed under different conditions, have been evaluated. The scintillation crystals obtained under such conditions have a high scintillation yield, demonstrate short scintillation kinetics with the major component of ∼60 ns, and demonstrate high radiation resistance when irradiated with both γ-quanta and high energy protons. The obtained results open up the opportunity to produce high-temperature garnet crystals using iridium-free technology, which forms the basis for a technology for mass production at an affordable price.
... For neutron rejection in addition the calorimeter shower properties and the time of arrival can be explored. It can be shown that the required background reduction is achievable with existing detector (calorimeter) technologies: time resolution 2 of [57,[59][60][61]. To conclude this discussion, we note that even a subset of these specifications is sufficient to meet our minimal requirements for the search. ...
... The natural region for the scalar model is below the brown dashed-dotted line.∼ O(10 − 100) ps[57][58][59], energy resolution of a few percent and finally, position and angular resolutions of ∼ O(100) µm and ∼ O(100) mrad respectively ...
We propose a novel way to search for feebly interacting massive particles, exploiting two properties of systems involving collisions between high energy electrons and intense laser pulses. The first property is that the electron-intense-laser collision results in a large flux of hard photons, as the laser behaves effectively as a thick medium. The second property is that the emitted photons free-stream inside the laser and thus for them the laser behaves effectively as a very thin medium. Combining these two features implies that the electron-intense-laser collision is an apparatus which can efficiently convert UV electrons to a large flux of hard, co-linear photons. We further propose to direct this unique large and hard flux of photons onto a physical dump which in turn is capable of producing feebly interacting massive particles, in a region of parameters that has never been probed before. We denote this novel apparatus as ``optical dump'' or NPOD (new physics search with optical dump). The proposed LUXE experiment at Eu.XFEL has all the required basic ingredients of the above experimental concept. We discuss how this concept can be realized in practice by adding a detector after the last physical dump of the experiment to reconstruct the two-photon decay product of a new spin-0 particle. We show that even with a relatively short dump, the search can still be background free. Remarkably, even with a 40 TW laser, which corresponds to the initial run, and definitely with a 350 TW laser, of the main run with one year of data taking, LUXE-NPOD will be able to probe uncharted territory of both models of pseudo-scalar and scalar fields, and in particular probe natural of scalar theories for masses above 100 MeV.
... Their relative ease of machining and handling, also thanks to the lack of hygroscopicity, combined with their transparency and long attenuation length facilitates employment in high aspect-ratio geometry detectors. One prominent example are fibres in spaghetti calorimeters (SPACAL) [12], which are being considered for the upgrade of the LHCb experiment electromagnetic calorimeter [13]. ...
Future colliders will set stringent requirements on the performance of detector materials in terms of timing and radiation hardness. Scintillating garnet crystals proved to satisfy the latter, while the former can be improved through technological developments. In this work, optical and scintillation properties of Cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) single crystals were studied upon gamma radiation excitation. Several 2x2x3 mm3 and 2x2x10 mm3 samples from various producers were characterised in terms of light output, transmission, scintillation kinetics and coincidence time resolution (CTR). Light output was measured using a ¹³⁷Cs radioactive source, ranging between 27900 and 49500 photons per MeV. Scintillation emission time profiles were measured with 511 keV gamma excitation, and the fastest samples displayed components below 70 ps rise time and 50 ns decay time. CTR was measured employing silicon photomultipliers (SiPMs) obtaining a best value of 87 ± 2 ps full width at half maximum, significantly improving on past state-of-the-art GAGG.
... This document explains the performance of the application of CNN for image classification with an upgraded calorimeter of LHCb for Run 5 of the LHC. In particular, the study has been done with simulation of a SPACAL module [8], a new technology that increases the image definition with smaller cells (one cell every 15 mm) and with separate front and rear sections, being the front 4 cm long and 10 cm the rear. Note that the final design of the upgraded calorimeter is still under discussion and that the small granularity used here would be implemented only in the innermost region of ECAL, with three other regions of increasing granularity. ...
The LHCb’s Electromagentic Calorimeter (ECAL) measures the energy that any particle leaves behind when it travels through its sensors. However, with the current granularity, it is not possible to exploit the shape of the shower produced by the particle when it interacts with the ECAL, which is an information that could be enough to conclude what particle is being detected. In an attempt to find out whether it would be possible to classify them in future runs of the LHC, simulated data is generated with Geant4, giving an idea of what SPACAL, an updated version of the current calorimeter with better resolution, is capable of. Convolutional Neural Networks are applied so that the algorithm can understand the shapes and energy deposits produced by each kind of particle. Results obtained demonstrate that bigger resolution in ECAL allows over 95% precision in some classifications such as photons against neutrons.
