Valence Quarks Polarization from COMPASS

A first evaluation of the polarized valence quark distribution $\Delta u_v(x)+\Delta d_v(x)$ from the COMPASS experiment (CERN/SPS) is presented. The data were collected by COMPASS in the years 2002--2004 using a 160 GeV polarized muon beam scattered off a large polarized $^6$LiD target and cover the range $1< Q^2 < 100$ GeV$^2$ and $0.006<x<0.7$. The analysis is based on the difference asymmetry, $A^{h^+ - h^-}$, for hadrons of opposite charges, which gives a direct access to the polarization of valence quarks.Comment: Talk given on XV Internetional Workshop on Deep-Inelastic Scattering and Related Subjects, April 16-20, 2007, Munich, German

Hadron production measurement from NA61/SHINE

New results of NA61/SHINE on determination of charged hadron yields in proton-carbon interactions are presented. They aim to improve predictions of the neutrino flux in the T2K experiment. The data were recorded using a secondary-proton beam of 31 GeV/$c$ momentum from CERN SPS which impinges on a graphite target. To determine the inclusive production cross section for charged pions, kaons and protons the thin ($0.04\, \lambda_I$) target was exploited. Results of this measurement are used in the T2K beam simulation program to reweight hadron yields in the interaction vertex. At the same time, NA61/SHINE results obtained with the T2K replica target ($1.9\, \lambda_I$) allow to constrain hadron yields at the surface of the target. It would correspond to the constraint up to 90% of the neutrino flux, thus reducing significantly a model dependence of the neutrino beam prediction. All measured spectra are compared to predictions of hadron production models. In addition a status of the analysis of data collected by NA61/SHINE for the NuMI target (Fermilab) is reviewed. These data will be used further in neutrino beam calculations for the MINERvA, MINOS(+) and LBNE experiments.Comment: Presented at EPS-HEP 2013 in Stockholm on July 19, 201

Valence Quarks Polarization from COMPASS

A first evaluation of the polarized valence quark distribution ∆uv(x) + ∆dv(x) from the COMPASS experiment (CERN/SPS) is presented. The data were collected by COMPASS in the years 2002-2004 using a 160 GeV polarized muon beam scattered off a large polarized 6 LiD target and cover the range 1 &lt; Q 2 &lt; 100 GeV 2 and 0.006 &lt; x &lt; 0.7. The analysis is based on the difference asymmetry, A h + −h − , for hadrons of opposite charges, which gives a direct access to the polarization of valence quarks

Beam test results of 3D fine-grained scintillator detector prototype for a T2K ND280 neutrino active target

An upgrade of the long baseline neutrino experiment T2K near detector ND280 is currently being developed with the goal to reduce systematic uncertainties in the prediction of number of events at the far detector Super-Kamiokande. The upgrade program includes the design and construction of a new highly granular fully active scintillator detector with 3D WLS fiber readout as a neutrino target. The detector of about $200\times 180\times 60~cm^3$ in size and a mass of $\sim$2.2~tons will be assembled from about $2\times10^6$ plastic scintillator cubes of $1\times1\times1~cm^3$. Each cube is read out by three orthogonal Kuraray Y11 Wave Length Shifting (WLS) fibers threaded through the detector. A detector prototype made of 125 cubes was assembled and tested in a charged particle test beam at CERN in the fall of 2017. This paper presents the results obtained on the light yield and timing as well as on the optical cross-talk between the cubes.Comment: 5 pages, 8 figure

Measurement of the longitudinal spin structure of the proton by COMPASS

The inclusive A_1,p and hadron double-spin asymmetries A_p^pi+, A_p^pi-, A_p^K+, A_p^K- measured at COMPASS (CERN SPS) in deep-inelastic scattering of a polarized muon beam off a polarized NH_3 solid target are presented. The results have been obtained with the full statistics collected in 2007 for the longitudinal target polarization. Proton asymmetries have been combined with the published deuteron ones. An evaluation of the non-singlet spin-dependent structure function g_1^NS(x,Q^2) and its first moment, which confirms the validity of the Bjorken sum-rule, is presented. A LO evaluation of polarized quark densities is also presented. The use of the proton data allows to perform a full flavor separation and to extract individual helicity densities of u, d, anti-u, anti-d and s quarks. All sea quark densities are found to be compatible with zero in the full range of the measurements.Comment: 4 pages, 5 figures, presented at the 3rd joint International HADRON STRUCTURE '09 Conference, Tatranska Strba (Slovak Republic

Application of large area SiPMs for the readout of a plastic scintillator based timing detector

In this study an array of eight 6 mm x 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm x 6 cm x 1 cm and 120 cm x 11 cm x 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results

Application of large area SiPMs for the readout of a plastic scintillator based timing detector

In this study an array of eight 6 mm x 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm x 6 cm x 1 cm and 120 cm x 11 cm x 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results

Study of timing characteristics of a 3 m long plastic scintillator counter using waveform digitizers

A plastic scintillator bar with dimensions 300 cm x 2.5 cm x 11 cm was exposed to a focused muon beam to study its light yield and timing characteristics as a function of position and angle of incidence. The scintillating light was read out at both ends by photomultiplier tubes whose pulse shapes were recorded by waveform digitizers. Results obtained with the WAVECATCHER and SAMPIC digitizers are analyzed and compared. A discussion of the various factors affecting the timing resolution is presented. Prospects for applications of plastic scintillator technology in large-scale particle physics detectors with timing resolution around 100 ps are provided in light of the results

Hadron calorimeter with MAPD readout in the NA61/SHINE experiment

The modular hadron calorimeter with micro-pixel avalanche photodiodes readout for the NA61/SHINE experiment at the CERN SPS is presented. The calorimeter consists of 44 independent modules with lead-scintillator sandwich structure. The light from the scintillator tiles is captured by and transported with WLS-fibers embedded in scintillator grooves. The construction provides a longitudinal segmentation of the module in 10 sections with independent MAPD readout. MAPDs with pixel density of $~10^{4}$/mm$^2$ ensure good linearity of calorimeter response in a wide dynamical range. The performance of the calorimeter prototype in a beam test is reported