Scintillation Light Detection with MAPD-3NK and MPPC-S12572-010P Readout

The linearity and energy resolution of two different solid-state photomultipliers (SiPMs) has been studied with reading out the LFS-8 scintillator (3x3x10 mm3). First SiPM (MAPD-3NK) from Zecotek Photonics consists of deeply burned pixels (cells) and has an active area of 3.7x3.7 mm2. The second one (MPPC-S12572-010P) from Hamamatsu has a surface cell structure and an active area of 3x3 mm2. Both SiPMs have the same pixel density of 10000 mm−2. Energy resolution and linearity of the SiPMs has been studied in the energy range of 59.6-1275 keV. It is found that both SiPMs demonstrate good linearity of signal amplitude as a function of the gamma ray energy in the studied energy range. The detector based on the MAPD-3NK provides significantly good energy resolution in comparison to the detector based on the MPPC-S12572-010P

Discrimination of SUSY breaking models using single-photon processes at future e+e- linear colliders

We examine the single-photon processes in the frame work of supersymmetric models at future e+e- linear colliders. According to the recent experimental achievement, the optimistic polarization degrees for both electron and positron beams are taken into account to enhance the signal-to-noise ratio revealing the observable difference between supersymmetry breaking models. The minimal supergravity model and the minimal SU(5) grand unified model in gaugino mediation have been examined as examples. We see that after several years of accummulating data, the difference of the number of single-photon events between the two models received from the collider would be in excess of three times the statistical error, providing us the possibility to probe which model would be realized in nature. The result is well suitable for the future running of the International Linear Collider.Comment: 14 pages, 4 figures, version to be published in Mod. Phys. Lett.

Investigation of the nuetralino pair production at LHC

In this article, we investigate the Drell-Yan process of the light neutralino pair $\widetilde{\chi}_{i}^{0}\widetilde{\chi}_{j}^{0}$ ($i,j=1,2$) productions at proton-proton collisions and we present the general formulate for the differential cross sections. We conduct an extensive examination of the dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0}\widetilde\chi_{j}^{0}$ on the beam energy, on the mass of the squarks and also on the $M_2$ gaugino for the three extremely different scenarios. For all three cases, the outcomes are as follows. The dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0} \widetilde \chi_{j}^{0}$ on the beam energy is dominated by one of the subprocesses, $q \bar q \to \widetilde \chi_{1}^{0} \widetilde \chi_{2}^{0}$. On the other hand, the dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0} \widetilde \chi_{j}^{0}$ on the mass of the squarks is dominated by one of the subprocesses, $q \bar q \to \widetilde \chi_{1}^{0} \widetilde \chi_{2}^{0}$. We derive there from that our findings may lead to new insights relating to experimental investigations and these dependencies may be used as bases of an experimental research for the neutralino pair at LHC.Comment: 38pp, 22 figures, ReVTeX4, (Baku State University, Azerbaijan, and Erciyes University, Kayseri, Turkey

The Meson Production in Proton-Proton Collisions in Next-To-Leading Order and Infrared Renormalons

In this article, we investigate the next-to-leading order contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions and present the general formulae for the higher-twist differential cross sections in the case of the running coupling and frozen coupling approaches. We compared the resummed next-to-leading order higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression (the Borel sum) are found. It is shown that the resummed result depends on the choice of the meson wave functions used in the calculations. We discuss the phenomenological consequences of possible higher-twist contributions to the meson production in proton-proton collisions in next-to-leading order at RHIC.Comment: 33 pages, 15 figures, 4 table

Portable neutron/gamma scintillation detector for status monitoring of accelerator-driven neutron source IREN

Accelerator-driven system (ADS) facilities world-wide opens new opportunities for nuclear physics investigations, so that a high flux of neutrons through spallation reactions can be produced at these facilities. It is known that the measurement, continuous monitoring and optimization of the particle accelerator beam intensity are among the most important actions in the operation of such facilities. Considering this point of view, this paper presents a neutron/gamma counter based on a micropixel avalanche photodiode (MAPD) and a plastic scintillator that monitors the status of the accelerator-driven intense resonance neutron source (IREN) facility by measuring the neutron-gamma intensity in the target hall. The electronics of the modular neutron counter has been designed and developed, including a bias voltage source (up to 130 V), a preamplifier (36 gain) and discriminator (>10 mV) circuit. The last product of MAPD (operation voltage- 55 V, PDE- 33 %, total number of pixels- 136900) was used as a photon readout from a plastic scintillator. The sensitive area of MAPD was 3.7*3.7 mm2 and the size of the plastic scintillator 3.7*3.7*30 mm3. The measurement was carried out in the IREN target hall, where it was necessary to monitor not only high neutron fluxes, but also gamma quanta. The experimental results demonstrated a dependence between the count rate of the detector and the frequency of the accelerator, which ranges from 2 to 50 Hz.Comment: 8 pages, 7 figure

Pion wave functions from holographic QCD and the role of infrared renormalons in photon-photon collisions

In this article, we calculate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single pion production cross section in photon-photon collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. Also, we show that in the context of frozen coupling approach a higher-twist contribution to the photon-photon collisions cross section is normalized in terms of the pion electromagnetic form factor.Comment: 21 pages, 15 figures. arXiv admin note: text overlap with arXiv:0709.2072 by other author

QED peripheral mechanism of pair production at colliders

Cross section of the processes of neutral pion production as well as pairs of charged fermions and bosons in peripherical interaction of leptons, photons are calculated in main logarithmical approximation. We investigate the phase volumes and differential cross sections. The differential cross section of few neutral pions and a few pairs production are written down explicitly. Considering the academic problem of summation on the number of pairs for the case of massless particles we reproduce the known results obtained in seventies of last century. The possibility to construct the generator for Monte-Carlo modeling of this processes basing of this results are discussed.Comment: 25 pages, 5 figure