Microchannel avalanche photodiode with wide linearity range

Design and physical operation principles of new microchannel avalanche photodiode (MC APD) with gain up to 10^5 and linearity range improved an order of magnitude compared to known similar devices. A distinctive feature of the new device is a directly biased p-n junction under each pixel which plays role of an individual quenching resistor. This allows increasing pixel density up to 40000 per mm^2 and making entire device area sensitive.Comment: Submitted to Journal of Technical Physic

Transverse-momentum-dependent Multiplicities of Charged Hadrons in Muon-Deuteron Deep Inelastic Scattering

A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality $Q^{2}>1$ (GeV/$c$)$^2$, invariant mass of the hadronic system $W > 5$ GeV/$c^2$, Bjorken scaling variable in the range $0.003 < x < 0.4$, fraction of the virtual photon energy carried by the hadron in the range $0.2 < z < 0.8$, square of the hadron transverse momentum with respect to the virtual photon direction in the range 0.02 (GeV/$c)^2 < P_{\rm{hT}}^{2} < 3$ (GeV/$c$)$^2$. The multiplicities are presented as a function of $P_{\rm{hT}}^{2}$ in three-dimensional bins of $x$, $Q^2$, $z$ and compared to previous semi-inclusive measurements. We explore the small-$P_{\rm{hT}}^{2}$ region, i.e. $P_{\rm{hT}}^{2} < 1$ (GeV/$c$)$^2$, where hadron transverse momenta are expected to arise from non-perturbative effects, and also the domain of larger $P_{\rm{hT}}^{2}$, where contributions from higher-order perturbative QCD are expected to dominate. The multiplicities are fitted using a single-exponential function at small $P_{\rm{hT}}^{2}$ to study the dependence of the average transverse momentum $\langle P_{\rm{hT}}^{2}\rangle$ on $x$, $Q^2$ and $z$. The power-law behaviour of the multiplicities at large $P_{\rm{hT}}^{2}$ is investigated using various functional forms. The fits describe the data reasonably well over the full measured range.Comment: 28 pages, 20 figure

Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality $Q^2>1~({\rm GeV}/c)^2$. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/$c$ polarised muon beam impinging on a polarised $^6$LiD target. By analysing the full range in hadron transverse momentum $p_{\rm T}$, the different $p_{\rm T}$-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation $\Delta g/g$ is evaluated at leading order in pQCD at a hard scale of $\mu^2= \langle Q^2 \rangle = 3 ({\rm GeV}/c)^2$. It is determined in three intervals of the nucleon momentum fraction carried by gluons, $x_{\rm g}$, covering the range $0.04 \!<\! x_{ \rm g}\! <\! 0.28$~ and does not exhibit a significant dependence on $x_{\rm g}$. The average over the three intervals, $\langle \Delta g/g \rangle = 0.113 \pm 0.038_{\rm (stat.)}\pm 0.036_{\rm (syst.)}$ at $\langle x_{\rm g} \rangle \approx 0.10$, suggests that the gluon polarisation is positive in the measured $x_{\rm g}$ range.Comment: 14 pages, 6 figure

Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target

Multiplicities of charged pions and unidentified hadrons produced in deep-inelastic scattering were measured in bins of the Bjorken scaling variable $x$, the relative virtual-photon energy $y$ and the relative hadron energy $z$. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target ($^6$LiD). They cover the kinematic domain in the photon virtuality $Q^2$ > 1(GeV/c$)^2$, $0.004 < x < 0.4$, $0.2 < z < 0.85$ and $0.1 < y < 0.7$. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions

First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA.

The NOvA experiment has seen a 4.4σ signal of ν[over ¯]_{e} appearance in a 2&nbsp;GeV ν[over ¯]_{μ} beam at a distance of 810&nbsp;km. Using 12.33×10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ¯]_{μ}→ν[over ¯]_{e} candidates with a background of 10.3 and 102 ν[over ¯]_{μ}→ν[over ¯]_{μ} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm_{32}^{2}|=2.48_{-0.06}^{+0.11}×10^{-3}  eV^{2}/c^{4} and sin^{2}θ_{23} in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ_{CP}=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ_{23} values in the upper octant by 1.6σ

Стандартные образцы времени жизни неравновесных носителей заряда в монокристаллическом кремнии

A comparison of two methods for measurement of the free carrier recombination lifetime in the unpassivated samples of high resistivity n-type silicon single crystalls (reference samples of "GIREDMET") was made. The methods were based on the photoconductivity decay measurements (High frequence and /-PCD). Effective recombination lifetime value in the range 1-1500 /is were achieved by changes of the sample thickness from 0,4 to 10 mm. Bulk recombination lifetime was calculated using the relation between the effective recombination lifetime and the sample thickness. It was shown that random and systematic errors for two methods are of the same order.Проведено сравнение результатов измерения эффективного времени жизни неравновесных носителей заряда на непассивированных пластинах высокоомного монокристаллического кремния в интервале эффективного времени жизни 10-1500 мкс и толщины 0,4-10 мм (СОП «ГИРЕДМЕТ») бесконтактными ВЧ- и СВЧ-мето-дами. Проведены оценки времени жизни в объеме материала по зависимости обратного эффективного времени жизни от квадрата обратной толщины в интервале толщины 1-4 мм. Показано, что приведенная в паспорте СОП погрешность результатов измерения ВЧ-методом в 10 % характеризует случайную погрешность измерения, величина которой одного порядка со случайной погрешностью измерения СВЧ-методом на установке с кольцевым зазором. Показано, что ВЧ- и СВЧ-методы имеют систематическую погрешность одного порядка

Анализ диффузионных профилей фосфора в легированном галлием германии методом координатно-зависимой диффузии

The phosphorus concentration profiles in germanium in In0,01Ga0,99As/In0,56Ga0,44P/Ge heterostructures with gallium co-diffusion, that were obtained during first cascade of a multicascade solar cell formation were analyzed. The diffusion of phosphorus took place from the layer In0,56Ga0,44P together with the diffusion of gallium in a strongly gallium-doped germanium substrate, which determined the features of the diffusion process. First of all, co-diffusion of gallium and phosphorus leads to formation of two p—n junctions. Fick’s laws cannot be used for diffusion description. Distribution of the P diffusivity (DP) in the depth of the sample was determined by two methods —Boltzmann—Matano (version of Sauer—Freise) and the coordinate-dependent diffusion method. It is shown that when we have used the coordinate-dependent diffusion method, the DP values are more consistent with the known literature data due to taking into account the drift component of diffusion. The tendency of DP to increase at the heterostructure boundary and to decrease at approaching to the main p—n junction is observed for both calculation methods. DP increase in the near-surface region of the p—n-junction, whose field is directed to the interface of the heterostructure, and the decrease in the region of the main p-n junction, whose field is directed in the opposite direction, as well as the observed growth of DP with the electron concentration, leads to the conclusion that diffusion in this case takes place as the part of negatively charged VGeP complexes, as in the case of P diffusion alone.В связи с развитием технологии многокаскадных солнечных элементов (МК СЭ) возрос интерес к германию как к подложке и материалу первого каскада МК СЭ на основе соединений АIIIВV. Фосфор и галлий являются основными легирующими элементами в германии, поэтому интерес к процессам их диффузии проявлялся с момента начала разработок технологии изготовления p—n-переходов в германии. Дан анализ профилей распределения фосфора в германии в структуре In0,01Ga0,99As/In0,56Ga0,44P/Ge в условиях содиффузии с галлием, полученные при формировании первого каскада МК СЭ. Диффузия фосфора проходила из слоя In0,56Ga0,44P вместе с диффузией галлия в сильно легированную галлием подложку германия, что определило особенности процесса диффузии. В первую очередь совместная диффузия галлия и фосфора приводит к формированию не одного, а двух p—n-переходов. Диффузионные профили фосфора не могут быть описаны законами Фика. Распределение коэффициента диффузии фосфора DP по глубине образца определяли двумя методами: Больцмана—Матано в варианте Зауэра—Фрейзе и методом координатно-зависимой диффузии. Показано, что учет дрейфовой компоненты в методе координатно-зависимой диффузии дает значения DP, более соответствующие известным литературным данным. Тенденция увеличения DP у границы гетероструктуры и уменьшения при приближении к основному переходу наблюдается для обоих методов расчета. Поле приповерхностного p—n-перехода, направлено к границе раздела гетероструктуры, а поле основного p—n-перехода — в противоположную сторону, также, как и наблюдаемый рост DP с концентрацией электронов. Увеличение DP в области приповерхностного p—n-перехода и уменьшение в области основного p—n-перехода позволяют сделать вывод, что диффузия в гетероструктуре идет в составе отрицательно заряженных комплексов VGeP, как и в случае диффузии одного компонента

ВЛИЯНИЕ УСЛОВИЙ ФОРМИРОВАНИЯ ПЕРВОГО КАСКАДА ТРЕХКАСКАДНОГО СОЛНЕЧНОГО ЭЛЕМЕНТА НА РАСПРЕДЕЛЕНИЕ ФОСФОРА В ГЕРМАНИИ

In0,01Ga0,99As/In0,56Ga0,44P /Ge structures for the first tandem of three−tandem A3B5/Ge solar cells were synthesized using MOS hydride epitaxy. The p—n–junction was formed by boron diffusion into gallium doped germanium. Phosphorus and gallium profiles in germanium were measured using SIMS. We show thatchanges in the phosphine flow do not affect the phosphorus distribution and the p—n–junction depth in the germanium stage.Методом МОС−гидридной эпитаксии изготовлены структуры In0,01Ga0,99As/In0,56Ga0,44P/Ge, представляющие собой первый каскад трехкаскадных солнечных элементов AIIIBV/Ge.P—n−переход сформирован диффузией фосфора в германий, легированный галлием. Методом ВИМС получены профили фосфора и галлия в германии. Показано, что изменение потока фосфина не влияет на характер распределения фосфора и глубину p—n−перехода в германиевом каскаде

Observation of seasonal variation of atmospheric multiple-muon events in the NOvA Near Detector

Using two years of data from the NOvA Near Detector at Fermilab, we report a seasonal variation of cosmic ray induced multiple-muon (Nμ≥2) event rates which has an opposite phase to the seasonal variation in the atmospheric temperature. The strength of the seasonal multiple-muon variation is shown to increase as a function of the muon multiplicity. However, no significant dependence of the strength of the seasonal variation of the multiple-muon variation is seen as a function of the muon zenith angle, or the spatial or angular separation between the correlated muons