The large barrel-shaped, shashlyk-type electromagnetic calorimeter (ECal) is an important part of the Multi-Purpose Detector (MPD) of the heavy-ion NICA experiment, and is designed to provide spatial ...and energy measurements for photons and electrons in the energy range from 40 MeV to 2-3 GeV. To deal with the high multiplicity, the ECal is finely segmented and made up of 38,400 cells ('towers') which are grouped into modules of 16 'towers' each. ECal projective geometry of the 'towers' oriented towards the beam interaction zone results in 8 different types of modules depending on their position in the ECal. As beam calibration of each individual 'tower' is time and resource expensive, we discuss our strategy of calibration for the ECal modules with cosmic muons and present some preliminary results.
A projective geometry description of the MPD Electromagnetic Calorimeter (ECal) has been developed and implemented within the MpdRoot software framework. Using this package, characteristics of the ...detector were studied by Monte Carlo methods. Information about energy and spatial resolution as well as registration efficiency was obtained for different clustering procedures. One module of the detector, developed at JINR, was tested using electron beam at DESY. Energy scan for this prototype was carried out to estimate detector linearity. Results of the simulations and beam tests are presented.
In the frame of the GEANT4 toolkit, a numerical simulation of light collection from the tower of the EMC MPD / NICA detector was carried out. The influence of reflective coatings of the scintillator ...surface, the propagation of light in fibers, taking into account their multilayer structure and light reflection from their ends, as well as the effects of joining a fiber bundle with an MPPC photodetector are considered. The temporal forms of the light signal at the MPPC input were obtained taking into account only geometric effects.
The report describes the Monte-Carlo simulation software developed for the projective geometry version of the electromagnetic calorimeter of the MPD detector. The results of software tests and some ...characteristics of the calorimeter are presented.
Novel micropixel avalanche photodiodes (MAPD) with super high pixel density Anfimov, N.; Chirikov-Zorin, I.; Dovlatov, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
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In many detectors based on scintillators the photomultiplier tubes (PMTs) are used as photodetectors. At present photodiodes are finding wide application. Solid state photodetectors allow operation ...in strong magnetic fields that are often present in applications, e.g. some calorimeters operating near magnets, combined PET and MRT, etc. The photon detection efficiency (PDE) of photodiodes may reach values a few times higher than that of PMTs. Also, they are rigid, compact and have relatively low operating voltage. In the last few years Micropixel Avalanche PhotoDiodes (MAPD) have been developed and started to be used. The MAPD combines a lot of advantages of semiconductor photodetectors and has a high gain, which is close to that of the PMT. Yet, they have some disadvantages, and one of them is a limited dynamic range that corresponds to a total number of pixels. The novel deep microwell MAPD with high pixel density produced by the Zecotek Company partially avoids this disadvantage. In this paper characteristics of these photodetectors are presented in comparison with the PMT characteristics. The results refer to measurements of the gain, PDE, cross-talks, photon counting and applications: beam test results of two different “Shashlyk” EM calorimeters for COMPASS (CERN) and NICA-MPD (JINR) with the MAPD readout and a possibility of using the MAPD in PET.
Prostate cancer (PCa) is one of the most common oncological diseases, which passes through two stages in its development: localized PCa and castration-resistant PCa (CR-PCa). The first ...stage—localized prostate cancer—can proceed indefinitely in a dormant form that does not require active medical intervention, or suddenly turn into an aggressive metastatic form (CR-PCa)
,
ending in rapid death. The pathogenesis of the transition of the dormant form of PCa to the metastatic form remains not fully understood. The signaling pathways of tumor suppressor pRb and proto-oncogene β-catenin are probably the most involved in the pathogenesis of prostate cancer, but the role of their interaction has not been studied. The publication on the pathogenesis of tumors in other tissues suggests that pRb may lose some properties of a tumor suppressor at the initial stage of PCa development due to its interaction with β-catenin that enables tumor cells to gain competitive advantages for reproduction. In this work, we showed that the genes
RB
and β-catenin (
CTNNB1
) are expressed in tumor and normal prostate tissue. Unlike β-catenin, pRb is not detected by immunoblotting in tumor and normal prostate tissue, but is easily detected in this way in extracts of control T98G cells. Co-immunoprecipitation with antibodies to pRb from extracts of tumor and normal prostate tissue makes it possible to detect this protein and β-catenin by subsequent immunoblotting, which indicates the physical interaction of these proteins in prostate tissue. On the other hand, immunoprecipitation of β-catenin with antibodies to its C-terminal fragment does not make it possible to detect this protein in prostate extracts by subsequent immunoblotting using the same antibodies. In contrast to prostate tissue, β-catenin was readily detected by immunoprecipitation coupled with immunoblotting in extracts of control T98G cells. The obtained data suggest that pRb and β-catenin physically interact with each other in cells of different tissue specificity. In T98G cells, this interaction probably occurs through the C-terminal fragment of β-catenin, but in prostate cells it occurs in a different way, since the C fragment of β-catenin is shielded from such interaction, possibly due to its physical association with pRb.
The main properties of two different Shashlyk EM calorimeter modules readout by novel micropixel avalanche photodiodes (MAPD) with microwell structure and very high density of pixels were studied at ...the T9 CERN PS test-beam facility. A MAPD-3A with density of pixels 1.5×10
4
mm
−2 and area 3×3
mm
2 manufactured by Zecotek Company was used in our test.
A brief description of the calorimeter and its original design is given. The main attention is paid to the development of the simulation code and its testing, as well as to the assessment of the ...influence of structural elements on the characteristics of the calorimeter. First results on the way of simulating its time response are presented.
The 60-ton cylindrical electromagnetic calorimeter of the MPD facility of the NICA project with a diameter of 3.45 m and a length of 6 m under construction is assembled from 50 half-sectors, each ...containing 768 “Shashlik” towers of different sizes and different spatial orientations. The paper proposes methods for calibrating half-sector towers using cosmic muons passing both along and across the axes of the towers. The results of testing these methods on the first manufactured half-sector are presented.
A
bstract
First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on
π
+
and
K
+
meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn ...and Pb at 3.2 A GeV. Transverse momentum distributions, rapidity spectra and multiplicities of
π
+
and
K
+
mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.
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