Commissioning and operation of the Cherenkov detector for proton Flux Measurement of the UA9 Experiment

The UA9 Experiment at CERN-SPS investigates channeling processes in bent silicon crystals with the aim to manipulate hadron beams. Monitoring and characterization of channeled beams in the high energy accelerators environment ideally requires in-vacuum and radiation hard detectors. For this purpose the Cherenkov detector for proton Flux Measurement (CpFM) was designed and developed. It is based on thin fused silica bars in the beam pipe vacuum which intercept charged particles and generate Cherenkov light. The first version of the CpFM is installed since 2015 in the crystal-assisted collimation setup of the UA9 experiment. In this paper the procedures to make the detector operational and fully integrated in the UA9 setup are described. The most important standard operations of the detector are presented. They have been used to commission and characterize the detector, providing moreover the measurement of the integrated channeled beam profile and several functionality tests as the determination of the crystal bending angle. The calibration has been performed with Lead (Pb) and Xenon (Xe) beams and the results are applied to the flux measurement discussed here in detail.Comment: 25 pages, 14 figure

Temperature and Bias Voltage Dependence of the MPPC Detectors

to appear in the IEEE Transactions on Nuclear ScienceInternational audienceThis work reports on the characterization of the Multi-Pixel Photon Counter (MPPC) detectors as a function of the temperature and bias voltage. Devices of 1x1 mm2 and 3x3 mm2 total area and 50x50 µm2 µcell size produced by Hamamatsu Photonics have been studied. The temperature has been varied from -110°C to -50°C using a cryostat cooled by liquid nitrogen and from 0 to 38°C using a climatic chamber. Important electrical parameters of the MPPC detectors as gain, breakdown voltage, quenching resistance, capacitance and dark count rate have been measuredsubstrate (on the rear side) and by a metal layer (on the front side). Each µcell is represented by a p+/n junction working in Geiger-mode connected in series with its integrated passive quenching resistance. The detectors are operated with each µcell biased to a bias voltage Vbias above the breakdown voltage VBD. The Vbias exceeds the VBD by an amount called overvoltage ΔV = Vbias – VBD, which has a critical influence on detector performance

PHIL photoinjector test line

LAL is now equiped with its own platform for photoinjectors tests and Research and Developement, named PHIL (PHotoInjectors at LAL). This facility has two main purposes: push the limits of the photoinjectors performances working on both the design and the associated technology and provide a low energy (MeV) short pulses (ps) electron beam for the interested users. Another very important goal of this machine will be to provide an opportunity to form accelerator physics students, working in a high technology environment. To achieve this goal a test line was realised equipped with an RF source, magnets and beam diagnostics. In this article we will desrcibe the PHIL beamline and its characteristics together with the description of the first two photoinjector realised in LAL and tested: the ALPHAX and the PHIN RF Guns

Characteristics of a prototype matrix of Silicon PhotoMultipliers (SiPM)

International audienceThis work reports on the electrical (static and dynamic) as well as on the optical characteristics of a prototype matrix of Silicon Photomultipliers (SiPM). The prototype matrix consists of 4 × 4 SiPM's on the same substrat fabricated at FBK-irst (Trento, Italy). Each SiPM of the matrix has an area of 1 × 1mm2 and it is composed of 625 microcells connected in parallel. Each microcell of the SiPM is a GM-APD (n+/p junction on P+ substrate) with an area of 40 × 40 μm2 connected in series with its integrated polysilicon quenching resistance. The static characteristics as breakdown voltage, quenching resistance, post-breakdown dark current as well as the dynamic characteristics as gain and dark count rate have been analysed. The photon detection efficiency as a function of wavelength and operation voltage has been also estimated

High-efficiency deflection of high energy protons due to channeling along the (110) axis of a bent silicon crystal

A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110) planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles

The Clacton Spear: the last one hundred years

In 1911 an eminent amateur prehistorian pulled the broken end of a pointed wooden shaft from Palaeolithic-age sediments at a seaside town in Essex. This artefact, still the earliest worked wood to be discovered in the world, became known as the Clacton Spear. Over the past 100 years it has variously been interpreted as a projectile weapon, a stave, a digging stick, a snow probe, a lance, a game stake and a prod to ward off rival scavengers. These perspectives have followed academic fashions, as the popular views of early hominins have altered. Since discovery the Clacton spear has also been replicated twice, has undergone physical transformations due to preservation treatments, and has featured in two public exhibitions. Within this article the changing context of the spear, its parallels, and all previous conservation treatments and their impacts are assessed.© 2015 Royal Archaeological Institute. This is an Accepted Manuscript of an article published by Taylor & Francis in The Archaeological Journal on 3rd March 2015, available online: http://www.tandfonline.com/doi.org/10.1080/00665983.2015.1008839.The attached document is the author(’s’) final accepted/submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it

Large scale dynamics in turbulent Rayleigh-Benard convection

The progress in our understanding of several aspects of turbulent Rayleigh-Benard convection is reviewed. The focus is on the question of how the Nusselt number and the Reynolds number depend on the Rayleigh number Ra and the Prandtl number Pr, and on how the thicknesses of the thermal and the kinetic boundary layers scale with Ra and Pr. Non-Oberbeck-Boussinesq effects and the dynamics of the large-scale convection-roll are addressed as well. The review ends with a list of challenges for future research on the turbulent Rayleigh-Benard system.Comment: Review article, 34 pages, 13 figures, Rev. Mod. Phys. 81, in press (2009

The ThomX project status

Work supported by the French Agence Nationale de la recherche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI - http://accelconf.web.cern.ch/AccelConf/IPAC2014/papers/wepro052.pdfA collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay - France. After a period of study and definition of the machine performance, a full description of all the systems has been provided. The infrastructure work has been started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different technical and experimental activities on optical resonators, RF power supplies and on the electron gun