The CLAS12 large area RICH detector

Abstract A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/ c up to momenta exceeding 8 GeV/ c and to be able to work at the very high design luminosity-up to 10 35 cm 2 s −1 . Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C 6 F 14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported

Global fitting of single spin asymmetry: an attempt

We present an attempt of global analysis of Semi-Inclusive Deep Inelastic Scattering (SIDIS) $\ell p^\uparrow \to \ell' \pi X$ data on single spin asymmetries and data on left-right asymmetry $A_N$ in $p^\uparrow p \to \pi X$ in order to simultaneously extract information on Sivers function and twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman (ETQS) function. We explore different possibilities such as node of Sivers function in $x$ or $k_\perp$ in order to explain "sign mismatch" between these functions. We show that $\pi^\pm$ SIDIS data and $\pi^0$ STAR data can be well described in a combined TMD and twist-3 fit, however $\pi^\pm$ BRAHMS data are not described in a satisfactory way. This leaves open a question to the solution of the "sign mismatch". Possible explanations are then discussed.Comment: 11 pages, 7 figure

The CLAS12 Software Framework and Event Reconstruction

We describe offline event reconstruction for the CEBAF Large Acceptance Spectrometer at 12 GeV (CLAS12), including an overview of the offline reconstruction framework and software tools, a description of the algorithms developed for the individual detector subsystems, and the overall approach for charged and neutral particle identification. We also present the scheme for data processing and the code management procedures

A Method to Polarize Stored Antiprotons to a High Degree

Polarized antiprotons can be produced in a storage ring by spin--dependent interaction in a purely electron--polarized hydrogen gas target. The polarizing process is based on spin transfer from the polarized electrons of the target atoms to the orbiting antiprotons. After spin filtering for about two beam lifetimes at energies $T\approx 40-170$ MeV using a dedicated large acceptance ring, the antiproton beam polarization would reach $P=0.2-0.4$. Polarized antiprotons would open new and unique research opportunities for spin--physics experiments in $\bar{p}p$ interactions

A bulk superconducting MgB2 cylinder for holding transversely polarized targets

An innovative solution is being pursued for the challenging magnetic problem of producing an internal transverse field around a polarized target, while shielding out an external longitudinal field from a detector. A hollow bulk superconductor can trap a transverse field that is present when cooled through its transition temperature, and also shield its interior from any subsequent field changes. A feasibility study with a prototype bulk MgB2 superconducting cylinder is described. Promising measurements taken of the interior field retention and exterior field exclusion, together with the corresponding long-term stability performance, are reported. In the context of an electron scattering experiment, such a solution minimizes beam deflection and the energy loss of reaction products, while also eliminating the heat load to the target cryostat from current leads that would be used with conventional electromagnets

Use of infrared thermography (IRT) in equine assisted interventions: physiological aspects

Infrared imaging thermography (IRT) is a technique widely used in wildlife studies and the assessment of animal welfare is among its fields of application. The heat emitted from superficial capillaries changes as blood flow is under control of the autonomic nervous system. For this reason, cutaneous temperature on selected areas can be considered as a good indicator of the health status and welfare of a particular individual. These changes in heat emitted can be quantified using IRT. The system consists of an infrared camera FLIR A65 (640 512 pixel, uncooled microbolometer detector, thermal sensitivity 0.05 \ub0C) with a 7\ub0 and 13\ub0 angle of view germanium tele lenses and a dedicated laptop. In the case of chimpanzees\u2019 studies, most of the available data derive from subjects kept in small enclosures, with little ecological validity. The aim of this research was to develop an infrared method allowing the acquisition of thermographic videos and images of animals at long distance. The system was tested on a group of eleven chimpanzees, in semi-natural conditions, housed at Parco Natura Viva in Bussolengo (Verona). The study ran between April and December 2016. Images and videos were shot at distance greater than 10 meters, during the everyday chimpanzees\u2019 life. The accuracy and repeatability of measurements was that typically reserved to the image acquisition with closer subjects at indoor conditions. Through this system it was possible to detect temperature variations in face layers by distinguishing the facial features of the subject. Thus, despite the distance from the animals, thanks to the good resolution of the system, the cutaneous temperatures were detected. In conclusion, IRT could be able to non-invasively detect different autonomic responses of the chimpanzees to different situations, suggesting that this system could be a valuable tool to study the chimpanzee\u2019s behavior and welfare at long distance

Test of the CLAS12 RICH large scale prototype in the direct proximity focusing configuration

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed with the hadron beam of the CERN T9 experimental hall for the direct detection configuration. The tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.Comment: 15 pages, 23 figures, to appear on EPJ