Search

The Mu2e experiment at Fermilab will search for the charged lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus [1] , [2] . The Mu2e detector is comprised of a tracker, an electromagnetic calorimeter, and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast and online trigger filter while aiding the track reconstruction capabilities. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach: 1) a time resolution better than 0.5 ns at 100 MeV; 2) an energy resolution O(10%) at 100 MeV; and 3) a position resolution of about 1 cm. The calorimeter consists of two disks, each one made of 674 pure CsI crystals readout by two large-area $2 \times 3$ array of UV-extended silicon photomultipliers (Mu2e SiPMs) of $6\,\,\times6$ mm2 dimensions. A large-scale prototype has been constructed with 51 preproduction crystals readout by 102 Mu2e SiPMs. It has been tested at the beam test facility in Frascati, demonstrating satisfying results compared to the Mu2e requirements. At the moment of writing, the crystals production phase is halfway through the work, while the SiPM production has been completed. An overview of the characterization tests is also reported, together with a description of the final calorimeter design.

The Mu2e experiment at Fermilab will search for the CLFV neutrino-less coherent conversion of a muon into an electron in the field of an aluminum nucleus. The observation of this process would be the evidence of physics beyond the Standard Model. Mu2e comprises a straw-tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter provides electron identification, a fast trigger and aids track reconstruction. It is a state-of-the-art crystal calorimeter and employs 1340 pure CsI crystals readout by UV-extended SiPM and fast electronics. The design consists of two identical annular disks positioned at the relative distance of 70 cm downstream the target.The hostile Mu2e conditions (total ionizing dose of 12 krad and a neutron fluence of 5 × 1010 n/cm2 @ 1 MeVeq (Si)/y, 1 T magnetic field and vacuum level of 10−4 Torr) posed tight constraints on the mechanical structures and materials choice. The support structure of the two crystal matrices employs two aluminum hollow rings and parts made of open-cell vacuum-compatible carbon fiber. SiPMs and front-end electronics for each crystal are assembled in one mechanical unit inserted in a machined copper holder. The units are supported by a plate made of vacuum-compatible material. The plate integrates the cooling system made of a network of copper lines flowing a low temperature fluid and placed in thermal contact with the copper holders. The DAQ is hosted in aluminum crates positioned on the lateral surface of the disks. The crates also integrate the DAQ electronics cooling system. We review the constraints on the calorimeter structures design, the development of all the structural components, including the simulations that have determined the materials and technological choices and the specifications of the cooling station, components production and quality assurance tests, the procedures for detector assembly, transportation and installation in the experimental area.

Currently, special attention is paid to the development of human capital. The article focuses on the assessment of the differentiation of human capital in the regions of Russia and the analysis of the mutual influence of human capital on socioeconomic development. For these purposes, a data set of 19 parameters of 2018 for 84 regions of the Russian Federation was formed. Special technical tools were used for factor and cluster analysis including Python and SciPy library. Interregional differentiation in the development of human capital leads to a strengthening of the positions of the leading regions and an increase in the backlog of “outsiders”. The concentration of human capital is observed in regions where large industrial enterprises, strong universities and scientific organizations have historically coexisted.

A High-Granularity Timing Detector (HGTD) is proposed based on the Low-Gain Avalanche Detector (LGAD) for the ATLAS experiment to satisfy the time resolution requirement for the up-coming High Luminosity at LHC (HL-LHC). We report on beam test results for two proto-types LGADs (BV60 and BV170) developed for the HGTD. Such modules were manufactured by the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences (CAS) collaborated with Novel Device Laboratory (NDL) of the Beijing Normal University. The beam tests were performed with 5 GeV electron beam at DESY. The timing performance of the LGADs was compared to a trigger counter consisting of a quartz bar coupled to a SiPM readout while extracting reference SiPM by fitting with a Gaussian function. The time resolution was obtained as 41 ps and 63 ps for the BV60 and the BV170, respectively. To meet the timing resolution requirement of up-coming High Luminosity LHC (HL-LHC), a new detector based on the Low-Gain Avalanche Detector(LGAD), High-Granularity Timing Detector (HGTD), is under intensive research in ATLAS. Two types of IHEP-NDL LGADs(BV60 and BV170) for this update is being developed by Institute of High Energy Physics (IHEP) of Chinese Academic of Sciences (CAS) cooperated with Novel Device Laboratory (NDL) of Beijing Normal University and they are now under detailed study. These detectors are tested with $5GeV$ electron beam at DESY. A SiPM detector is chosen as a reference detector to get the timing resolution of LGADs. The fluctuation of time difference between LGAD and SiPM is extracted by fitting with a Gaussian function. Constant fraction discriminator (CFD) method is used to mitigate the effect of time walk. The timing resolution of $41 \pm 1 ps$ and $63 \pm 1 ps$ are obtained for BV60 and BV170 respectively.

We report on the results of a radiation campaign with neutrons and protons of Low Gain Avalanche Detectors (LGAD) produced by Hamamatsu (HPK) as prototypes for the High-Granularity Timing Detector (HGTD) in ATLAS. Sensors with an active thickness of 50μm were irradiated in steps of roughly 2 × up to a fluence of 3 ×1015neqcm−2 . As a function of the fluence, the collected charge and time resolution of the irradiated sensors will be reported for operation at −30 °C. We report on the results of a radiation campaign with neutrons and protons of Low Gain Avalanche Detectors (LGAD) produced by Hamamatsu (HPK) as prototypes for the High-Granularity Timing Detector (HGTD) in ATLAS. Sensors with an active thickness of 50~$\mu$m were irradiated in steps of roughly 2$\times$ up to a fluence of $3\times10^{15}~\mathrm{n_{eq}cm^{-2}}$. As a function of the fluence, the collected charge and time resolution of the irradiated sensors will be reported for operation at $-30^{\circ}$.

The High-Granularity Timing Detector is a detector proposed for the ATLAS Phase II upgrade. The detector, based on the Low-Gain Avalanche Detector (LGAD) technology will cover the pseudo-rapidity region of $2.4, Comment: 17 pages, 20 figures

Приведены результаты исследований питьевой воды системы централизованного водоснабжения г. Самары. При определении органолептических показателей качества воды было выявлено увеличение цветности исходных проб на 13 град в пределах погрешности метода измерения. Это может быть связано с высоким содержанием железа и его соединений или гуминовых веществ в пробах в дни проведения эксперимента, а также с высоким физическим износом водопроводных сетей (как уличных, так и внутри здания) и общим ростом цветности воды в Саратовском водохранилище в районе г. Самары за последние годы. Установлена зависимость -потенциала от величины окислительно-восстановительного потенциала и ионного состава воды. Определен физико-химический состав изучаемой воды, сделан анализ полученных результатов. В ходе исследований дополнительно определялись такие показатели, как pH, температура, мутность и щелочность для получения полной картины качества воды. Установлено соответствие всех изучаемых показателей воды нормам СанПиН 2.1.4.1074-01 Питьевая вода. Гигиенические требования к качеству воды централизованных систем питьевого водоснабжения. Контроль качества . Приведены математические зависимости между -потенциалом, жесткостью, содержанием анионов и катионов в исследуемой воде с достоверностью аппроксимации R2 не ниже 0,83. Это позволяет рассчитать ионный состав и мутность питьевой воды г. Самары только по величине -потенциала или окислительно-восстановительного потенциала без проведения дорогостоящих трудоемких химических анализов. Предлагаемый метод рекомендуется использовать в качестве экспресс-анализа питьевой воды.The results of studies of drinking water in the public water supply system of the city of Samara are presented. While determining the organoleptic indicators of the water quality, an increase in color of the initial samples by 13 degrees within the procedural error was revealed. This may be due to the high concentration of iron and its compounds or humic substances in the samples on the days of the experiment, as well as to the high physical deterioration of the water distribution networks (both street networks and plumbing in the buildings), and the general increase in water color in the Saratov water reservoir in the city of Samara in recent years. The dependence of the -potential on the redox potential value and ion composition of water is established. The physicochemical composition of the studied water is determined, an analysis of the results is carried out. In the course of the research, such indicators as pH, temperature, turbidity and alkalinity were additionally determined to obtain an aggregate picture of the water quality. The compliance of all studied water indicators with the requirements of SanPiN 2.1.4.1074-01 Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control was confirmed. Mathematical dependences between the -potential, hardness, and the concentration of anions and cations in the water under study are given with an approximation authenticity R2 higher than 0.83. This allows calculating the ion composition and turbidity of drinking water in Samara only by the value of the -potential or redox potential without expensive labor-intensive chemical analyzes. The proposed method is recommended to be used as an express analysis of drinking water.

This is a proceeding of 12th international "Hiroshima" Symposium on the Development and Application of Semiconductor Tracking Detectors. This paper studied the radiation hardness of low gain avalanche detector (LGAD) developed by the Novel Device Laboratory (NDL) in Beijing and The Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences. NDL LGAD sensors with different layouts, epitaxial resistivity, doping profile were irradiated up to 1.02E15 N_eq/cm^2 by 70MeV proton at Cyclotron and Radioisotope Center (CYRIC). The timing resolution of NDL LGAD reached 40-50$ps$ and the collected charge reached 3-4$fC$ after irradiation This is a proceeding of 12th international "Hiroshima" Symposium on the Development and Application of Semiconductor Tracking Detectors. This paper studied the radiation hardness of low gain avalanche detector (LGAD) developed by the Novel Device Laboratory (NDL) in Beijing and The Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences. NDL LGAD sensors with different layouts, epitaxial resistivity, doping profile were irradiated up to 1.02E15 N_eq/cm^2 by 70MeV proton at Cyclotron and Radioisotope Center (CYRIC). The timing resolution of NDL LGAD reached 40-50$ps$ and the collected charge reached 3-4$fC$ after irradiation

BaF 2 crystals are considered as a perspective scintillator to create detectors for high-energy physics. An attention of physicist is attracted by its high radiation strength and short decay time ( 2 crystals and suppress the slow component are presented.

The Mu2e calorimeter is composed of two disks each containing 1348 pure CsI crystals, each crystal read out by two arrays of 6x6 mm2 monolithic SiPMs. The experimental requirements have been translated in a series of technical specifications for both crystals and SiPMs. Quality assurance tests, on first crystal and then SiPM production batches, confirm the performances of preproduction samples previously assembled in a calorimeter prototype and tested with an electron beam. The production yield is sufficient to allow the construction of a calorimeter of the required quality in the expected times., Comment: 2 pages, 2 figures, 14th meeting on Advanced Detectors

The Mu2e experiment at Fermilab will search for the charged-lepton flavour violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The calorimeter plays an important role in providing a fast trigger filter, excellent particle identification and a seeding for track reconstruction. Its requirements are to provide an energy (timing) resolution better than 10% (0.5 ns) and a position resolution below 1 cm, for 100 MeV electrons. The calorimeter consists of two disks, each one made of 674 un-doped CsI crystals readout by two large area arrays of 2 × 3 UV-extended SiPMs of 6 × 6 mm^2 dimensions. A large scale prototype (Module-0) has been constructed and tested with an electron beam in the energy range between 60 and 120 MeV at the BTF of Frascati National Laboratories. Results demonstrated that this calorimeter satisfies the Mu2e requirements.

The Mu2e electromagnetic calorimeter is made of two disks of un-doped parallelepiped CsI crystals readout by SiPM. There are 674 crystals in one disk and each crystal is readout by an array of two SiPM. The readout electronics is composed of two types of modules: 1) the front-end module hosts the shaping amplifier and the high voltage linear regulator; since one front-end module is interfaced to one SiPM, a total of 2696 modules are needed for the entire calorimeter; 2) a waveform digitizer provides a further level of amplification and digitizes the SiPM signal at the sampling frequency of $200\ \text{M}\text{Hz}$ with 12-bits ADC resolution; since one board digitizes the data received from 20 SiPMs, a total of 136 boards are needed. The readout system operational conditions are hostile: ionization dose of $20\ \text{krads}$, neutron flux of $10^{12}\ \mathrm{n}(1\ \text{MeVeq})/\text{cm}^2$, magnetic field of $1\ \text{T}$ and in vacuum level of $10^{-4}\ \text{Torr}$. A description of the readout system and qualification tests is reported.

In this paper, we present measurements of the energy and the time resolution of the Lutetium–Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The prototype calorimeter matrix consisted of 25, $\hbox{3}\,\hbox{$\times$}\, \hbox{3}\,\hbox{$\times$}\, \hbox{130\ mm}^3$ , LYSO crystals readout by $10\ \times 10\ \hbox{mm}^2$ Hamamatsu APDs. The prototype has been tested both with the tagged photon beam at MAMI, Mainz, Germany, and with the ${e^ -}$ beam of BTF, Frascati. The energy of particles used ranges between 61.3 and 187.1 MeV (80–130 MeV) for photon (electron) beams. While the MAMI data shows a negligible beam energy spread, we observe a 3%–5% contribution related to the beam in BTF sample. After correcting this effect, we obtain a global energy dependence of the energy resolution described by the formula ${\sigma _{E}}/{{E}_{{\rm {dep}}}}= {a}/\sqrt {{{E}_{{\rm {dep}}}}/{\hbox{GeV}}} \oplus {b}$ , with ${a} = ({0.59} \pm {0.12})\%$ and ${b} = ({3.63} \pm {0.21})\% $ . The simulation is in good agreement with data if we add an additional contribution due to the intrinsic LYSO fluctuation of 2.6%. We present also the measurements of the time resolution. The measurements have been performed using the ${e^ -}$ beam BTF in the energy range from 100 to 400 MeV. A resolution of ( ${161} \pm {3}$ ) ps at 100 MeV has been achieved. The energy dependence of the resolution has been fitted with following parametrization: ${\sigma _{\rm t}}{\rm (E)} = {a}/\sqrt {{E}/{\hbox{GeV}}} \oplus {b}$ , where the stochastic term and the constant term are determined to be ${a} = ({50} \pm {1})$ ps and ${b} = ({40} \pm {3})$ ps, respectively.

The Mu2e experiment at Fermilab will search for the charged-lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities and a fast online trigger filter, while aiding the track reconstruction capabilities. Calorimeter requirements are to provide a large acceptance for 0∼10 MeV electrons and reach: I) a time resolution better than 0.5 ns; ii) an energy resolution better than 10%; and iii) a position resolution of 1 cm. The calorimeter consists of two disks, each one made of 674 pure CsI crystals. Each crystal is readout by two large area 2×3 arrays of UV-extended SiPMs of 6×6 mm2 dimensions. A large scale prototype (Module-0) has been tested at an electron beam. We report here the tests done to finalize the calorimeter design, the results obtained with Module-0 and the status of production. At this time, the performance characteristics of 85% of the crystals and all of the SiPMs have been measured. The calorimeter engineering drawings have been completed and the large mechanical components are under fabrication. Analog and digital electronics have been prototyped and tested with irradiation dose. Their serial production is being organized. The calorimeter assembly phase is planned for mid-2020.

The Mu2e experiment at Fermilab searches for the coherent neutrino-less muon to electron conversion in the Coulomb field of an aluminum nucleus. This charged-lepton flavor violating process is characterized by a distinctive signature of a mono-energetic electron ( ∼ 105 MeV/c) and its observation will be a clear signature of new physics beyond the Standard Model. The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast online trigger filter while aiding the track reconstruction capabilities. It consists of 1348 pure CsI crystals divided in two annular disks, each one readout by two large area Silicon Photomultipliers. A large scale prototype has been tested with an electron beam , demonstrating to largely satisfy the Mu2e requirements. At the moment of writing, the crystals and SiPMs production phase is halfway through the completion. An overview of the characterization tests is reported, together with a description of the final mechanical and electronical design.

Since the first version of the Mu2e TDR released at the beginning of 2015, the Mu2e Calorimeter system has undergone a long list of changes to arrive to its final design. These changes were primarily caused by two reasons: (i) the technology choice between the TDR proposed solution of BaF2 crystals readout with solar blind Avalanche Photodiodes (APDs) and the backup option of CsI crystals readout with Silicon Photomultipliers (SiPM) has been completed and (ii) the channels numbering, the mechanical system and the readout electronics were substantially modified while proceeding with engineering towards the final project. This document updates the description of the calorimeter system adding the most recent engineering drawings and tecnical progresses.

The Mu2e experiment is constructing a calorimeter consisting of 1,348 undoped CsI crystals in two disks. Each crystal has a dimension of 34 x 34 x 200 mm, and is readout by a large area silicon PMT array. A series of technical specifications was defined according to physics requirements. Preproduction CsI crystals were procured from three firms: Amcrys, Saint-Gobain and Shanghai Institute of Ceramics. We report the quality assurance on crystal's scintillation properties and their radiation hardness against ionization dose and neutrons. With a fast decay time of 30 ns and a light output of more than 100 p.e./MeV measured with a bi-alkali PMT, undoped CsI crystals provide a cost-effective solution for the Mu2e experiment., Comment: 7 pages, 16 figures, published in IEEE TNS NS (2018)

The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less $��\to e$ coherent conversion in the field of an aluminum nucleus. Mu2e will reach a single event sensitivity of about $2.5\cdot 10^{-17}$ that corresponds to four orders of magnitude improvements with respect to the current best limit. The detector system consists of a straw tube tracker and a crystal calorimeter made of undoped CsI coupled with Silicon Photomultipliers. The calorimeter was designed to be operable in a harsh environment where about 10 krad/year will be delivered in the hottest region and work in presence of 1 T magnetic field. The calorimeter role is to perform $��$/e separation to suppress cosmic muons mimiking the signal, while providing a high level trigger and a seeding the track search in the tracker. In this paper we present the calorimeter design and the latest R$\&$D results., 4 pages, conference proceeding for a presentation held at TIPP'2017. To be published on Springer Proceedings in Physics

The Mu2e experiment at Fermilab will search for Charged Lepton Flavor Violating conversion of a muon to an electron in an atomic field. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external system, surrounding the solenoid, to veto cosmic rays. The calorimeter plays an important role to provide: a) excellent particle identification capabilities; b) a fast trigger filter; c) an easier tracker track reconstruction. Two disks, located downstream of the tracker, contain 674 pure CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs. The choice of the crystals and SiPMs has been finalized after a thorough test campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in Frascati. Although the readout electronics were not the final, results show that the current design is able to meet the timing and energy resolution required by the Mu2e experiment., Comment: 6 pages, 8 figures, proceedings of the "Calorimetry for the high energy frontier (CHEF17)" conference, 2-6 October 2017, Lyon, France

The Mu2e experiment at Fermilab will search for the coherent $\mu \to e$ conversion on aluminum atoms. The detector system consists of a straw tube tracker and a crystal calorimeter. A pre-production of 150 Silicon Photomultiplier arrays for the Mu2e calorimeter has been procured. A detailed quality assur- ance has been carried out on each SiPM for the determination of its own operation voltage, gain, dark current and PDE. The measurement of the mean-time-to-failure for a small random sample of the pro-production group has been also completed as well as the determination of the dark current increase as a function of the ioninizing and non-ioninizing dose., Comment: 4 pages, 10 figures, conference proceeding for NSS-MIC 2017

The Mu2e experiment at Fermilab searches for the charged-lepton flavour violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive signature of a mono-energetic electron of energy slightly below the muon rest mass (104.967 MeV). The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. Any observation of a CLFV signal will be a clear indication of new physics. The Mu2e detector is composed of a tracker, an electro- magnetic calorimeter and an external veto for cosmic rays surrounding the solenoid. The calorimeter plays an important role in providing particle identification capabilities, a fast online trigger filter, a seed for track reconstruction while working in vacuum, in the presence of 1 T axial magnetic field and in an harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100 MeV electrons and reach at these energies: (a) a time resolution better than 0.5 ns; (b) an energy resolution < 10% and (c) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674 undoped CsI crystals read by two large area arrays of UV-extended SiPMs. We report here the construction and test of the Module-0 prototype. The Module-0 has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati. Preliminary results of timing and energy resolution at normal incidence are shown. A discussion of the technical aspects of the calorimeter engineering is also reported in this paper., 8 pages, 16 figures, submitted to IEEE

The Mu2e experiment at Fermilab looks for Charged Lepton Flavor Violation (CLFV) improving by 4 orders of magnitude the current experimental sensitivity for the muon to electron conversion in a muonic atom. A positive signal could not be explained in the framework of the current Standard Model of particle interactions and therefore would be a clear indication of new physics. In 3 years of data taking, Mu2e is expected to observe less than one background event mimicking the electron coming from muon conversion. Achieving such a level of background suppression requires a deep knowledge of the experimental apparatus: a straw tube tracker, measuring the electron momentum and time, a cosmic ray veto system rejecting most of cosmic ray background and a pure CsI crystal calorimeter, that will measure time of flight, energy and impact position of the converted electron. The calorimeter has to operate in a harsh radiation environment, in a 10-4 Torr vacuum and inside a 1 T magnetic field. The results of the first qualification tests of the calorimeter components are reported together with the energy and time performances expected from the simulation and measured in beam tests of a small scale prototype., Comment: 11 pages, 7 figures, proceedings of 14th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD16) 3 - 6 October 2016 Siena, Italy, Journal of Instrumentation, Volume 12, January 2017 http://stacks.iop.org/1748-0221/12/i=01/a=C01061

The Mu2e calorimeter is composed by $\sim 1400$ un- doped CsI crystals coupled to large area UV extended Silicon Photomultipliers(SIPMs) arranged intwo annular disks. This calorimeter has to provide precise information on energy, timing and position resolution. It should also be fast enough towithstand the high rate background and it mustoperate and survive in a high radiation environment. All steps done for the construction and test of the Module -0 prototype, that is an array of51 pre-production crystals, are reported. The Module -0 was exposed to an electron beam in the energy range around 100 MeV at the BTF (Beam Test Facility) inFrascati. Preliminary results of timing and energy resolution at normal incidence are shown.

We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60$-$450 MeV. This study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment., 2 pages, 3 figures, 13th Pisa Meeting on Advanced Detectors

The Mu2e experiment at Fermilab aims at measuring the neutrinoless conversion of a negative muon into an electron and reach a single event sensitivity of 2.5x10^{-17} after three years of data taking. The monoenergetic electron produced in the final state, is detected by a high precision tracker and a crystal calorimeter, all embedded in a large superconducting solenoid (SD) surrounded by a cosmic ray veto system. The calorimeter is complementary to the tracker, allowing an independent trigger and powerful particle identification, while seeding the track reconstruction and contributing to remove background tracks mimicking the signal. In order to match these requirements, the calorimeter should have an energy resolution of O(5)% and a time resolution better than 500 ps at 100 MeV. The baseline solution is a calorimeter composed of two disks of BaF2 crystals read by UV extended, solar blind, Avalanche Photodiode (APDs), which are under development from a JPL, Caltech, RMD consortium. In this paper, the calorimeter design, the R&D studies carried out so far and the status of engineering are described. A backup alternative setup consisting of a pure CsI crystal matrix read by UV extended Hamamatsu MPPC's is also presented., 5 pages, 6 figures

In this paper we present the time resolution measurements of the Lutetium-Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the $e^-$ beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30x30x130 mm$^3$, LYSO crystals read out by 10x10 mm$^2$ Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as $\sigma_{t}(E)=a/\sqrt{E/\mathrm{GeV}} \oplus b$, with the stochastic and constant terms $a=(51\pm1)$ ps and $b=(10\pm4)$ ps, respectively. This corresponds to the time resolution of ($162\pm4$) ps at 100 MeV., Comment: 18 pages, 14 figures, accepted for the journal Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The reaction of 6-bromo-7-cyclopropyl-1,4-benzodioxane with N2O4 in methylene chloride does not affect the cyclopropane ring and forms the nitrodebrominated product (ipso-substitution). The same reaction of 6-nitro- and 5,6-dinitro-7-cyclopropyl-1,4-benzodioxanes produces only the products with an modified threemembered ring. The difference in the reaction paths of the studied cyclopropylbenzodioxanes with N2O4 is explained by the different ratio of substrate to one-electron oxidant, the nitrosyl cation.

The reaction of 6-bromo-7-cyclopropyl-1,4-benzodioxane with N2O4 in methylene chloride does not affect the cyclopropane ring and forms the nitrodebrominated product (ipso-substitution). The same reaction of 6-nitro- and 5,6-dinitro-7-cyclopropyl-1,4-benzodioxanes produces only the products with an modified threemembered ring. The difference in the reaction paths of the studied cyclopropylbenzodioxanes with N2O4 is explained by the different ratio of substrate to one-electron oxidant, the nitrosyl cation.

Bromination of 6-cyclopropyl-1,4-benzodioxane occurs with concerted orientation of the ethylenedioxy group and the cyclopropyl radical for the least sterically hindered position of the aromatic ring. Nitration of 6-bromo-7-cyclopropyl-1,4-benzodioxane does not lead to products of substitution of the hydrogen atom in the 5 or 8 position of the 1,4-benzodioxane, but rather to the nitrodebromination product: 7-nitro-6-cyclopropyl-1,4-benzodioxane. The anomalous behavior of the bromo-substituted benzodioxane is explained by the predisposition of the carbon atom bonded to the bromine towardipso attack by an electrophile.

The Mu2e experiment at Fermi National Accelerator Laboratory searches for the charged-lepton flavor violation neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. This decay results in a mono- energetic electron with energy slightly below the muon rest mass. The design of the Mu2e experiment has been studied to reach a single event sensitivity that is four order of magnitudes better than previous experiments.The Mu2e calorimeter plays an important role to provide particle identification and an online trigger filter. After a long period of R&D conducted both at INFN and Caltech on the different components, the final technical choice has been made and the calorimeter now consists of two disks, each one made by about 700 un-doped CsI crystals read out by two large area UV-extended silicon photomultipliers.In this paper, we describe the main components of the detector and the tests performed on a large size calorimeter prototype (Module 0) that has been equipped with final crystals, photosensors, front-end electronics and cooling system.

The Mu2e calorimeter consists of 1348 pure CsI crystals coupled to two large area UV-extended Silicon Photomultipliers (SiPMs) organized in two separate annular disks. An intense R&D phase has been pursued to check if this configuration satisfies the Mu2e requirements. In May 2017, a dedicated test has been performed at the Beam Test Facility (BTF) in Frascati (Italy) where the large calorimeter prototype (Module-0) has been exposed to an electron beam in the energy range between 60 and 120 MeV. The prototype consists of 51 crystals, each one readout by two Mu2e SiPMs. We present results for timing and energy resolution both for electrons at normal incidence (0°) and at a grazing impact angle (50°) more similar to the experiment configuration. At 100 MeV, an energy resolution of 5.4% (7.4%) at normal (grazing) incidence has been achieved in good agreement with Monte Carlo expectation. In the same energy range, a time resolution of ~ XX ps (~ YY ps) has been measured at normal incidence with 1 GHz (250 MHz) sampling rate. Dependence of time and energy resolutions as a function of beam energy and impinging angle are also presented.