The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive ...signature of a monoenergetic 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 electromagnetic 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 a harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach at these energies: 1) a time resolution better than 0.5 ns; 2) an energy resolution <10%; and 3) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674-undoped cesium iodine crystals read by two large area arrays of UV-extended silicon photomultipliers (SiPMs). We report here the construction and the 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.
The fast component of the barium fluoride (BaF2) crystal luminescence with the emission peak at 220 nm allows those crystals to be employed in fast calorimeters operating in harsh radiation ...environment. However, the slow component with the emission peak at 330 nm and about 85% of the total emission light could create big problems when working at a high radiation rate. In this work we report results of tests of multilayer filters that can suppress luminescence in the range from 250 nm to 400 nm, which covers most of the BaF2 slow component luminescence. The filters are made by spraying layers of rare earth oxides on a quartz glass substrate. Filters typically comprise 200-220 layers. A few filters were prepared by spraying thin layers on quartz glass. The filters have a peak transmittance of about 70-80% in the range of 200-250 nm. Measurements of the light output of the BaF2 crystal with and without a filter between the crystal readout end and the PMT demonstrate substancial suppression of the slow component. To our knowledge, this kind of filters are produced and tested for the first time.
The results of developing a compact version of the Precision Laser Inclinometer (CPLI) with the reduced overall dimensions of 20 × 20 × 20 cm and weight of 10 kg are presented. Experimental data on ...detected angular oscillations of the Earth’s surface at the JINR site are obtained. The achieved sensitivity is 6 × 10
–11
rad/Hz
1/2
in the frequency range 1.4 × 10
–3
–10 Hz. The CPLI can be used in modern physical experiments for seismic isolation of large-scale installations. Reduction of the impact of microseismic angular oscillations of the Earth’s surface on the sensitive elements of the VIRGO Interference Gravitational Antenna, the Large Hadron Collider, and NICA will increase the accuracy of the experiments.
This paper presents the results of measuring the parameters of scintillation cubes, which are elements of the active target of the upgraded near detector of the T2K experiment, with the scintillation ...of a polystyrene-based organic scintillator being excited by an ultraviolet LED. Most attention is paid to the study of light leaks through the side faces of the cubes. The measurement results show that an average value of the coefficient characterizing light leaks through one face of the cube is 0.026. The effect of heating scintillation cubes on the light collection from them and light leaks are studied. After keeping the cubes at a temperature of 60°C for 72 h, the light collection from the cubes and the light leaks remained at the same level.
This study compares seasonal and spatial variations in methane fluxes as sources of uncertainty in regional CH4 flux upscaling from the wetlands of West Siberia. The study examined variability in ...summertime CH4 emissions from boreal peatlands, with a focus on two subtaiga fen sites in the southern part of West Siberia (Novosibirskaya oblast). We measured CH4 flux, water table depth, air and peat temperature, pH and electric conductivity of peat water during three field campaigns in summer 2011 (9-12 July, 26-28 July and 20-21 August). Fluxes were measured with static chambers at sites chosen to represent two of the most widespread types of wetlands for this climatic zone: soligenous poor fens and topogenous fens. In both sites the water table level acts as the primary control on fluxes. For the poor fen site with good drainage, water table controls CH4 fluxes on the seasonal scale but not on a local spatial scale; for the fen site with weak drainage and microtopographic relief, the water table controls fluxes on the local spatial scale, but does not drive seasonal variations in the flux magnitude. This difference in hydrology shows the necessity of including detailed wetland type classification schemes into large-scale modeling efforts. From these three measurement periods, we estimated the relative seasonal variation in CH4 emissions as 8% for the fen site and 26% for the poor fen site. These results were compared to estimates of other sources of uncertainty (such as interannual variation and spatial heterogeneity) to show that quantifying seasonal variability is less critical than these other variations for an improved estimate of regional CH4 fluxes. This research demonstrates and ranks the challenges in upscaling measured wetland CH4 fluxes across West Siberia and can guide future field campaigns.
The differential cross sections of the charge exchange reaction
d
p
→
(
p
p
)
n
has been measured at 1.75 GeV/c per nucleon for small transferred momenta using the one arm magnetic spectrometer ...STRELA at the Nuclotron accelerator in JINR Dubna. The ratio of the differential cross section of the charge exchange reaction
d
p
→
(
p
p
)
n
to that of the
n
p
→
p
n
elementary process is discussed in order to estimate the spin-dependent part of the
n
p
→
p
n
charge exchange amplitude. The
n
p
→
p
n
amplitude turned out to be predominantly spin-dependent.
The Mu2e experiment is constructing a calorimeter consisting of 1348 undoped cesium iodide (CsI) crystals in two disks. Each crystal has a dimension of 34 × 34 × 200 mm3 and is readout by a ...large-area silicon photomultipliers array. A series of technical specifications on mechanical and optical parameters was defined according to the calorimeter 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 about 30 ns and a light output of more than 100 p.e./MeV measured by a bialkali photomultiplier tube, undoped CsI crystals provide a cost-effective solution for Mu2e.
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