B. Rossi

NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary 7Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area. The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility - the beams and the detector system - before the CERN Long Shutdown I, which started in March 2013.

In this paper, we report on the clinical application of fully automated three-dimensional intensity modulated proton therapy, as applied to a 34-year-old patient presenting with a thoracic chordoma. Due to the anatomically challenging position of the lesion, a three-field technique was adopted in which fields incident through the lungs and heart, as well as beams directed directly at the spinal cord, could be avoided. A homogeneous target dose and sparing of the spinal cord was achieved through field patching and computer optimization of the 3D fluence of each field. Sensitivity of the resultant plan to delivery and calculational errors was determined through both the assessment of the potential effects of range and patient setup errors, and by the application of Monte Carlo dose calculation methods. Ionization chamber profile measurements and 2D dosimetry using a scintillator/CCD camera arrangement were performed to verify the calculated fields in water. Modeling of a 10% overshoot of proton range showed that the maximum dose to the spinal cord remained unchanged, but setup error analysis showed that dose homogeneity in the target volume could be sensitive to offsets in the AP direction. No significant difference between the MC and analytic dose calculations was found and the measured dosimetry for all fields was accurate to 3% for all measured points. Over the course of the treatment, a setup accuracy of +/-4 mm (2 s.d.) could be achieved, with a mean offset in the AP direction of 0.1 mm. Inhalation/exhalation CT scans indicated that organ motion in the region of the target volume was negligible. We conclude that 3D IMPT plans can be applied clinically and safely without modification to our existing delivery system. However, analysis of the calculated intensity matrices should be performed to assess the practicality, or otherwise, of the plan.

Plasma measurements were made with a detector aboard the Explorer 10 satellite, launched on a highly elongated elliptical trajectory with the line of apsides about 33° to the antisolar direction. Magnetic field measurements were also carried out on Explorer 10 by the Goddard Space Flight Center of NASA. A plasma moving with a velocity of about 300 km sec−1 was first observed when the satellite reached a distance of about 22 earth radii. During the rest of the observations (which terminated about 40 hours later, at a distance of 42 earth radius, periods in which substantial plasma fluxes were recorded alternated with shorter periods in which the plasma flux was below or just above the detection limit. There was a striking correlation between the plasma flux and the magnetic field: in the absence of plasma the magnetic field direction was nearly radial from the earth, whereas in the presence of plasma, the field was irregular and generally formed large angles with the earth-satellite direction. The plasma probe did not provide accurate information on the direction of the plasma flow, but placed the direction within a ‘window’ of about 20° by 80°. This window includes the direction pointing radially away from the sun. The flux densities of the positive ions (presumably protons) corresponding to the observed currents were of the order of a few times 108 cm−2 sec−1. They fluctuated over a range of about a factor of 2 during the periods when plasma was observed.

The ArgoNeuT liquid argon time projection chamber has collected thousands of neutrino and anti-neutrino events during an extended run period in the NuMI beam-line at Fermilab. This paper focuses on the main aspects of the detector layout and related technical features, including the cryogenic equipment, time projection chamber, read-out electronics, and off-line data treatment. The detector commissioning phase, physics run, and first neutrino event displays are also reported. The characterization of the main working parameters of the detector during data-taking, the ionization electron drift velocity and lifetime in liquid argon, as obtained from through-going muon data complete the present report.

We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics.Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei.We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm.For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm.We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils.Assuming that the energy loss partitions into excitons and ion pairs from 83m Kr internal conversion electrons is comparable to that from 207 Bi conversion electrons, we obtained the numbers of excitons (N ex ) and ion pairs (N i ) and their ratio (N ex /N i ) produced by nuclear recoils from 16.9 to 57.3 keV.Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large-scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatus employ three different and, to some extent, complementary detection techniques: GLACIER (liquid Argon TPC), LENA (liquid scintillator) and MEMPHYS (\WC), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical- and geo-neutrinos and to the possible use of these detectors in future high-intensity neutrino beams.

Spectra of positively charged kaons in $p+\text{C}$ interactions at 31 GeV/$c$ were measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2007 with a graphite target with a thickness of 4$%$ of a nuclear interaction length. Interaction cross sections and charged pion spectra were already measured using the same set of data. These new measurements in combination with the published ones are required to improve predictions of the neutrino flux for the T2K long-baseline neutrino oscillation experiment in Japan. In particular, the knowledge of kaon production is crucial for precisely predicting the intrinsic electron neutrino component and the high-energy tail of the T2K beam. The results are presented as a function of laboratory momentum in two intervals of the laboratory polar angle covering the range from 20 to 240 mrad. The kaon spectra are compared with predictions of several hadron production models. Using the published pion results and the new kaon data, the ${K}^{+}$/${\ensuremath{\pi}}^{+}$ ratios are computed.

The ArgoNeuT Collaboration presents the first measurements of inclusive muon neutrino charged current differential cross sections on argon. Obtained in the NuMI neutrino beam line at Fermilab, the flux-integrated results are reported in terms of outgoing muon angle and momentum. The data are consistent with the Monte Carlo expectation across the full range of kinematics sampled, 0°<θμ<36° and 0<Pμ<25 GeV/c. Along with confirming the viability of liquid argon time projection chamber technology for neutrino detection, the measurements allow tests of low-energy neutrino scattering models important for interpreting results from long baseline neutrino oscillation experiments designed to investigate CP violation and the orientation of the neutrino mass hierarchy.Received 2 November 2011DOI:https://doi.org/10.1103/PhysRevLett.108.161802© 2012 American Physical Society

A liquid argon time projection chamber, constructed for the Argon Response to Ionization and Scintillation (ARIS) experiment, is exposed to the highly collimated and quasimonoenergetic LICORNE neutron beam at the Institut de Physique Nucl\'eaire d'Orsay (IPNO) in order to study the scintillation response to nuclear and electronic recoils. An array of liquid scintillator detectors, arranged around the apparatus, tag scattered neutrons and select nuclear recoil energies in the [7, 120] keV energy range. The relative scintillation efficiency of nuclear recoils is measured to high precision at null field, and the ion-electron recombination probability is extracted for a range of applied electric fields. Single-scattered Compton electrons, produced by gammas emitted from the deexcitation of $^{7}{\mathrm{Li}}^{*}$ in coincidence with the beam pulse, along with calibration gamma sources, are used to extract the recombination probability as a function of energy and electron drift field. The ARIS results are compared with three recombination probability parametrizations (Thomas-Imel, Doke-Birks, and PARIS), allowing for the definition of a fully comprehensive model of the liquid argon response to nuclear and electronic recoils down to the few-keV range. The constraints provided by ARIS to the liquid argon response at low energy allow the reduction of systematics affecting the sensitivity of dark matter search experiments based on liquid argon.

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.

We have exposed a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow-band neutron beam, produced at the Notre Dame Institute for Structure and Nuclear Astrophysics, to study the scintillation light yield of recoiling nuclei. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the LAr-TPC and to select the energy of the recoiling nuclei. We report the observation of a significant dependence (up to 32%) on the drift field of liquid argon scintillation from nuclear recoils of energies between 10.8 and 49.9 keV. The field dependence is stronger at lower energies. Since it is the first measurement of such an effect in liquid argon, this observation is important because, to date, estimates of the sensitivity of LAr-TPC dark matter searches are based on the assumption that the electric field has only a small effect on the light yield from nuclear recoils.

The instrument is designed to determine the density, direction, and magnitude of the bulk velocity of the protons of the interplanetary plasma. It is essentially a Faraday cup containing four grids which serve (a) to keep the electrons of the plasma from reaching the collector and (b) to suppress the photoelectric current by modulating the incoming protons without modulating the photoelectrons produced when the cup faces the sun. A transistorized electronic system amplifies, compresses, and demodulates the a-c signal from the collector before transmitting it to the telemetry system of the vehicle. Current densities from 10−12 to 10−8 amp/cm2, and proton kinetic energies from 10 to 3000 ev, can be measured.

The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid argon time projection chambers is now mature. The study of rare events, not contemplated in the standard model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the νμ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrates that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the multiple Coulomb scattering along the particle’s path. Moreover, we show that momentum resolution can be improved by almost a factor two using an algorithm based on the Kalman filtering technique.

Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne-yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the ``neutrino floor'' (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events.

The Liquid Argon Time Projection Chamber (LArTPC) is a prime type of detector for future large-mass neutrino observatories and proton decay searches. In this paper we present the design and operation, as well as experimental results from ARGONTUBE, a LArTPC being operated at the AEC-LHEP, University of Bern. The main goal of this detector is to prove the feasibility of charge drift over very long distances in liquid argon. Many other aspects of the LArTPC technology are also investigated, such as a voltage multiplier to generate high voltage in liquid argon (Greinacher circuit), a cryogenic purification system and the application of multi-photon ionization of liquid argon by a UV laser. For the first time, tracks induced by cosmic muons and UV laser beam pulses have been observed and studied at drift distances of up to 5m, the longest reached to date.

This paper reports on laser-induced multiphoton ionization at 266 nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: σex=(1.24±0.10stat±0.30syst)×10− 56 cm4 s− 1.

ArgoNeuT, or Argon Neutrino Test, is a 170 liter liquid argon time projection chamber designed to collect neutrino interactions from the NuMI beam at Fermi National Accelerator Laboratory. ArgoNeuT operated in the NuMI low-energy beam line directly upstream of the MINOS Near Detector from September 2009 to February 2010, during which thousands of neutrino and anti-neutrino events were collected. The MINOS Near Detector was used to measure muons downstream of ArgoNeuT. Though ArgoNeuT is primarily an R&D project, the data collected provide a unique opportunity to measure neutrino cross sections in the 0.1–10 GeV energy range. Fully reconstructing the muon from these interactions is imperative for these measurements. This paper focuses on the complete kinematic reconstruction of neutrino-induced through-going muons tracks. Analysis of this high statistics sample of minimum ionizing tracks demonstrates the reliability of the geometric and calorimetric reconstruction in the ArgoNeuT detector.

The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design we proposed for a revolutionary photon detector. The main idea is to replace the classical dynode chain of a PMT with a SiPM (G-APD), the latter acting as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performance of the SiPM technology. The VSiPMT has many attractive features. In particular, a low power consumption and an excellent photon counting capability. To prove the feasibility of the idea we first tested the performance of a special non-windowed SiPM by Hamamatsu (MPPC) as electron detector and current amplifier. Thanks to this result Hamamatsu realized two VSiPMT industrial prototypes. In this work, we present the results of a full characterization of the VSiPMT prototype.

IN recent years we have witnessed startling developments in the field of fundamental particles. One of the consequences has been the appearance in the scientific literature of a new jargon and of a large number of new symbols. Some symbols (such as π, µ, τ) designate specific kinds of particles. Others (such as ρ, σ) have been used to describe merely a phenomenological behaviour. Various authors have called the same particle by different names or have attached different meanings to the same symbol. Sometimes the meaning of a symbol has changed through the years. To give an example, the Greek letter χ was used initially to describe a heavy meson which stops in the emulsion and afterwards decays, giving rise to a single ionizing particle. Later, the Latin letter K replaced the Greek letter χ as a code for the above phenomenological description, while the letter χ acquired a more definite physical meaning: that of a heavy meson which decays into one charged and two neutral particles. Sometimes, however, the letter K is also used to designate any charged particle, heavier than a π-meson and lighter than a proton, the mode of decay of which is unknown. As another example, the neutral particle of mass about 1,000 m e, which decays into two π-mesons, has been variously named v 0, V 2 0, V 4 0, whereas some authors have used the letter V 2 0 to designate any V 0-particle different from the so-called V 1 0.

This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration play an important role. Results from the first measurements are presented together with some considerations and outlook.

The Liquid Argon Time Projection Chamber (LAr TPC) technique is a promising technology for future neutrino detectors. At LHEP of the University of Bern (Switzerland), an R&D program towards large detectors are on-going. The main goal is to show the feasibility of long drift paths over many meters. Therefore, a liquid Argon TPC with 5 m of drift distance was constructed. Many other aspects of the liquid Argon TPC technology are also investigated, such as a new device to generate high voltage in liquid Argon (Greinacher circuit), a recirculation filtering system and the multi-photon ionization of liquid Argon with a UV laser. Two detectors are built: a medium size prototype for specific detector technology studies, and ARGONTUBE, a 5 m long device.

Motivated by the ongoing study of a possible directional signal in liquid argon dark matter detectors, we introduce a new model describing the recombination of electron-ion pairs in ionizing tracks in liquid argon in the presence of a drift field. The emphasis is on the three-dimensional distribution of electrons and ions and on their orientation relative to that of the electric field. We successfully apply our model to describe the angular dependence of the ionization signal of protons recently reported in measurements performed by the ArgoNeuT Collaboration with a liquid argon time projection chamber.

We examine the sensitivity of a large scale two-phase liquid argon detector to the directionality of the dark matter signal. This study was performed under the assumption that, above 50 keV of recoil energy, one can determine (with some resolution) the direction of the recoil nucleus without head-tail discrimination, as suggested by past studies that proposed to exploit the dependence of columnar recombination on the angle between the recoil nucleus direction and the electric field. In this paper we study the differential interaction recoil rate as a function of the recoil direction angle with respect to the zenith for a detector located at the Laboratori Nazionali del Gran Sasso and we determine its diurnal and seasonal modulation. Using a likelihood-ratio based approach we show that, with the angular information alone, 100 events are enough to reject the isotropic hypothesis at three standard deviation level. For an exposure of 100 tonne years this would correspond to a spin independent WIMP-nucleon cross section of about 10^-46 cm^2 at 200 GeV WIMP mass. The results presented in this paper provide strong motivation for the experimental determination of directional recoil effects in two-phase liquid argon detectors.

In this paper we report on the evidence for ionization track signals from cosmic ray muons and Compton electrons in a Time Projection Chamber (TPC) filled with liquid Argon and doped with different fractions of Nitrogen. This study has been conducted in view of the possible use of liquid Argon/Nitrogen TPCs for the detection of gamma rays in the resonant band of the Nitrogen absorbtion spectrum, a promising technology for security and medical applications.

Pulse-shape discrimination of scintillation from alpha and beta particles with liquid scintillator and Geiger-mode multipixel avalanche diodes, I Kreslo, I Badhrees, S Delaquis, A Ereditato, S Janos, M Messina, U Moser, B Rossi, M Zeller

Abstract Muon spin relaxation has been measured in longitudinal and zero field configurations for a number of conducting polymers in the polypyrrole and polyaniline families. The measurements have been made as a function of temperature down to 11K and in applied fields up to 2000G. Hyperfine parameters have been deduced for the coupling between muon and polaron spins and the spin dynamics has been modeled on the basis of polaron diffusion, which has one-dimensional character at low temperatures, becoming more two-dimensional at room temperature.

For future neutrino oscillation experiments new large mass scale detectors are needed. One possible type of such detectors could be a liquid Argon Time Projection Chamber (LArTPC). Some technical challenges need to be addressed, like the purity of the LAr, the high voltage supply and calibration. To face these challenges, an R&D program is under development at the LHEP of the University of Bern. The goal is to reach a drift length of 5 m in liquid Argon and prove the feasibility of large volume TPCs. In this article, different aspects of the technology will be reviewed and recent achievements presented.

Next generation multi-ton scale noble liquid experiments have the unique opportunity to discover dark matter particles at the TeV scale, reaching the sensitivity of 10−48 cm2 in the WIMP nucleon scattering cross-section. A prerequisite will be the reduction of radiogenic background sources to negligible levels. This is only possible if ultra-pure high efficiency photosensors are available for the scintillation light readout. Current experiments (e.g. Xenon, LUX, Darkside, ArDM) use cryogenic PMTs as photosensors. An attractive alternative is represented by silicon photomultiplier arrays (SiPM arrays), which show unrivalled performances in single photon detection. This paper reports on the performance of the SensL-ArrayB-30035-16P SiPM array and a custom made cryogenic front-end board at the liquid argon temperature. Its performance at VOV=3.5 V, where the PDE is maximal, are very promising in terms of SPE resolution (about 8%), dark rate (about 250 Hz) and correlated pulses (30%).

Results obtained with the satellite Explorer X, which was designed to measure properties of the magnetic field and of the ionized gas over a region starting close to the earth and extending to a polnt where effects of the earth's magnetic field should be negligible, are presented. Instrumentation and the experimental conditions for the measure ments are described. Between approximately 1.3 and 2.9 R/sub e/ (earth radii), a plasma probe signal was present at all energy modulation levels. The slgnal was strongly modulated by the spin of the vehicle and arose from the presence of a relatlvely cold stationary plasma in this region. Between 2.9 and 21.5 Re, no signal was observed. At about 21.5 R/sub e/ a flux of positive particles of about 4 x 10/ sup 8/ cm/sup -2/ sec/sup -1/ at a mean energy of about 500 ev was observed for the first time. There were large fluctuations in the intensity of the flux. The presence of plasma coincided with a relatively weak magnetic field which fluctuated in magnitude and direction. The absence of plasma was associated with a relatively strong steady magnetic field directed away from the sun. (M.C.G.)

In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) flled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric feld in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar-N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications.

Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency

After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC), the collision rate and therefore the background rate will significantly increase, particularly in the high $\eta$ region. To improve both the tracking and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to install triple-layer Gas Electron Multiplier (GEM) detectors in the CMS muon endcaps. Demonstrator GEM detectors were installed in CMS during 2017 to gain operational experience and perform a preliminary investigation of detector performance. We present the results of triple-GEM detector performance studies performed in situ during normal CMS and LHC operations in 2018. The distribution of cluster size and the efficiency to reconstruct high $p_T$ muons in proton--proton collisions are presented as well as the measurement of the environmental background rate to produce hits in the GEM detector.

In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon.

The feasibility of a next generation neutrino observatory in Europe is being considered within the LAGUNA design study. To accommodate giant neutrino detectors and shield them from cosmic rays, a new very large underground infrastructure is required. Seven potential candidate sites in different parts of Europe and at several distances from CERN are being studied: Boulby (UK), Canfranc (Spain), Fr\'ejus (France/Italy), Pyh\"asalmi (Finland), Polkowice-Sieroszowice (Poland), Slanic (Romania) and Umbria (Italy). The design study aims at the comprehensive and coordinated technical assessment of each site, at a coherent cost estimation, and at a prioritization of the sites within the summer 2010.

A new gas detector prototype for the upgrade of the focal plane detector of the MAGNEX large-acceptance magnetic spectrometer has been developed and tested in view of the NUMEN project. It has been designed to operate at low gas pressure for detecting medium to heavy ions in the energy range between 15 and 60 AMeV. It is a drift chamber based on Multi-layer Thick-GEM (M-THGEM) as electron multiplication technology. Tests with two different M-THGEM layouts have been performed using both a radioactive $\alpha$-particle source and accelerated heavy-ion beams. The characterization of the detector in terms of measured currents that flow through the electrodes as a function of different parameters, including applied voltages, gas pressure and rate of incident particle, is described. The gain and ion backflow properties have been studied.

The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed for future generations of rare event search experiments using noble liquids. The main idea is to replace conventional multi-dynode photomultiplier tubes (PMTs) with a hybrid technology, consisting of a low temperature sensitive bialkali photocathode for conversion of photons into photoelectrons and a low dark count silicon photomultiplier (SiPM) for photoelectron signal amplification. SiGHT can achieve ultra low internal radioactivity, high quantum efficiency and stable performance at low temperatures, which are required features for rare event searches such as direct dark matter detection and neutrinoless double beta decay experiments. The first SiGHT prototype fabrication is in progress at UCLA. The current status of the development is presented.

This paper reports on multiphoton ionization at 266 nm of liquid Argon in a Time Projection Chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the monitoring of the next generation large mass LAr TPCs [1]. The detector we have designed and tested allowed us also to measure the two-photon absorption cross-section (σex) of LAr with unprecedented accuracy and precision, appropriate for using the UV laser technique also for a quantitative calibration of the detector.

LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a γ-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as trackerconverter.Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex.Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active.In this proceeding is described a plausible design for the tracker-converter detector which fulfills the constraints on conversion efficiency, angular resolution, and wide field of view.It is demonstrated how this design can provide an unprecedented angular resolution for a γ-ray telescope, leading to a significant improvement in sensitivity and most important disclosing the possibility to detect the polarization of γ-ray emission.

Abstract A comprehensive R&D program on LAr Time Projection Chambers (LAr TPC) is presently being carried out at the University of Bern. Many aspects of this technology are under investigation: HV, purity, calibration, readout, etc. Furthermore, multi-photon interaction of UV-laser beams with LAr has successfully been measured. Possible applications of the LAr TPC technology in the field of homeland security are also being studied. In this paper, the main aspects of the program will be reviewed and the achievements underlined. Emphasis will be given to the largest device in Bern, i.e. the 5 m long ARGONTUBE TPC, meant to prove the feasibility of very long drifts in view of future large scale applications of the technique.

In this paper we report on the evidence for ionization track signals from cosmic ray muons and Compton electrons in a Time Projection Chamber (TPC) filled with liquid Argon and doped with different fractions of Nitrogen. This study has been conducted in view of the possible use of liquid Argon/Nitrogen TPCs for the detection of gamma rays in the resonant band of the Nitrogen absorbtion spectrum, a promising technology for security and medical applications.

>It is not yet clear whether the conditions recorded by Explorer X beyond 22 earth radii were typical of interplanetary space or whether they were still affected by the earth's magnetic field. If the former assumption is correct, the observations of Explorer X indicate that the interplanetary plasma is divided into regions of two different types with linear dimensions of the order of 10/sup 11/ cm, separated by sharp boundaries. Measurements taken by Explorer X are summarized. (W.D.M.)

An estimate of environmental background hit rate on triple-GEM chambers is performed using Monte Carlo (MC) simulation and compared to data taken by test chambers installed in the CMS experiment (GE1/1) during Run-2 at the Large Hadron Collider (LHC). The hit rate is measured using data collected with proton-proton collisions at 13 TeV and a luminosity of 1.5$\times10^{34}$ cm$^{-2}$ s$^{-1}$. The simulation framework uses a combination of the FLUKA and Geant4 packages to obtain the hit rate. FLUKA provides the radiation environment around the GE1/1 chambers, which is comprised of the particle flux with momentum direction and energy spectra ranging from $10^{-11}$ to $10^{4}$ MeV for neutrons, $10^{-3}$ to $10^{4}$ MeV for $\gamma$'s, $10^{-2}$ to $10^{4}$ MeV for $e^{\pm}$, and $10^{-1}$ to $10^{4}$ MeV for charged hadrons. Geant4 provides an estimate of detector response (sensitivity) based on an accurate description of detector geometry, material composition and interaction of particles with the various detector layers. The MC simulated hit rate is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties of 10-14.5%. This simulation framework can be used to obtain a reliable estimate of background rates expected at the High Luminosity LHC.

Photomultiplier tubes (PMT) technology has been improved continuously in the last years: the quantum efficiency of the photocathode has now reached a level of 40%, close to the theoretical maximum; single photon sensitivity and time resolution have been improved by a careful design of electrostatic focusing on the 1st dynode; with new coatings the secondary electron yield of dynodes has greatly improved, reducing the required number of dynodes and their size.

We invented (2007) the VSiPMT, a novel, high-gain, photo detector device and we publically proposed this idea in an International Conference for the first time at the 11th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD08) in Siena, triggering deep discussions on the feasibility of the device itself and on the convenience of such a solution. After several years spent in designing, evaluation, tests and eventually negotiations with some suppliers, we finally got a couple of prototypes of the Vacuum Silicon Photo Multiplier Tube (VSiPMT) made under our specifications by Hamamatsu. We present in this paper the most important results of characterization tests of the first prototypes of the VSiPMT.

DarkSide-50 (DS-50) at Gran Sasso underground laboratory (LNGS), Italy, is a direct dark matter search experiment based on a TPC with liquid argon. DS-50 has completed its first dark matter run using atmospheric argon as target. The DS-50 detector performances and the results of the first physics run are reviewed in this proceeding.

DarkSide-50 at Gran Sasso underground laboratory (LNGS), Italy, is a direct dark matter search experiment based on a liquid argon TPC.DS-50 has completed its first dark matter run using atmospheric argon as target.The detector performances and the results of the first physics run are presented in this proceeding.

It is generally inferred from astronomical measurements that Dark Matter (DM) comprises approximately 27\% of the energy-density of the universe. If DM is a subatomic particle, a possible candidate is a Weakly Interacting Massive Particle (WIMP), and the DarkSide-50 (DS) experiment is a direct search for evidence of WIMP-nuclear collisions. DS is located underground at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, and consists of three active, embedded components; an outer water veto (CTF), a liquid scintillator veto (LSV), and a liquid argon (LAr) time projection chamber (TPC). This paper describes the data acquisition and electronic systems of the DS detectors, designed to detect the residual ionization from such collisions.

We have constructed a liquid Argon TPC detector with fiducial mass of 150 kg as a part of the R&amp;D program of the next generation neutrino and nucleon decay detector. This paper describes a study of particle identification performance of the detector using well-defined charged particles (pions, kaons, and protons) with momentum of ~800 MeV/$c$ obtained at J-PARC K1.1BR beamline.

LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a $\gamma$-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as tracker-converter. Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex. Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active. In this proceeding is described a plausible design for the tracker-converter detector which fulfills the constraints on conversion efficiency, angular resolution, and wide field of view. It is demonstrated how this design can provide an unprecedented angular resolution for a $\gamma$-ray telescope, leading to a significant improvement in sensitivity and most important disclosing the possibility to detect the polarization of $\gamma$-ray emission.

Institut de Fisica d’Altes Energies (IFAE), Barcelona, Spain LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a γ-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as trackerconverter. Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex. Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active. In this proceeding is described a plausible design for the tracker-converter detector which fulfills the constraints on conversion efficiency, angular resolution, and wide field of view. It is demonstrated how this design can provide an unprecedented angular resolution for a γ-ray telescope, leading to a significant improvement in sensitivity and most important disclosing the possibility to detect the polarization of γ-ray emission.

LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a $\gamma$-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as tracker-converter. Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex. Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active. In this proceeding is described a plausible design for the tracker-converter detector which fulfills the constraints on conversion efficiency, angular resolution, and wide field of view. It is demonstrated how this design can provide an unprecedented angular resolution for a $\gamma$-ray telescope, leading to a significant improvement in sensitivity and most important disclosing the possibility to detect the polarization of $\gamma$-ray emission.

Jan Kisiel Institute of Physics, University of Silesia Uniwersytecka 4, 40-007 Katowice, Poland E-mail: Jan.Kisiel@us.edu.pl D. Angusa, A. Arigab, D. Autieroc, A. Apostud, A. Badertschere, T. Bennetf, G. Bertolag, P.F. Bertolag, O. Besidah, A. Bettinii, C. Boothf, J.L. Bornec, I. Brancusd, W. Bujakowskij, J.E. Campagnec, G. Cata-Danild, F. Chipesiud, M. Chorowskik, J. Crippsf, A. Curionie, S. Davidsonc, Y.R.A Declaisc, U. Drostg, O. Duliul, J. Dumarchezc, T. Enqvistm, A. Ereditatob, F. v Feilitzschn, H. Fynboo, T. Gamblef, G. Galvaninp, A. Gendottie, W. Gizickik, M. GogerNeffn, U. Grassling, D. Gurneyq, M. Hakalar, S. Hannestado, M. Haworthq, A. Jipal, F. Jugetb, T. Kalliokoskis, S. Katsanevasc, M. Keent, I.Kreslob, V. Kudryastevf, P. Kuusiniemim, L. Labargau, T. Lachenmaiern, J.C. Lanfranchin, I. Lazanul, T. Lewken, K. Loom, P. Lightfootf, M. Lindnerv, P. Lombardiw, A. Longhinh, J. Maalampis, M. Marafinic, A. Marchionnie, R.M. Margineanud, A. Markiewiczx, T. Marrodan-Undagoitan, J.E. Marteauc, R. Matikainenr, Q. Meindln, M. Messinab, J.W. Mietelskiy, B. Mitricad, A. Mordasinig, L. Moscah, U. Moserb, G. Nuijtenr, L. Oberauern, A. Oprinad, S. Palingf, S. Pascolia, T. Patzakc, M. Pectud, Z. Pileckij, F. Piquemalc, W. Potzeln, W. Pytelx, M. Raczynskix, G. Raffeltz, G. Ranucciw, G. Ristainop, M. Robinsonf, R. Rogersq, J. Roinistor, M. Romanai, E. RondioA, B. Rossib, A. Rubbiae, Z. Sadeckix, C. Saenzi, A. Saftoiud, J. Salmelainenr, O. Simal, J. Slizowskij, K. Slizowskij, J. SobczykB, N. Spoonerf, S. Stoicad, J. Suhonens, R. SulejA, M. Szarskay, T. SzeglowskiC, M. Temussip, J. Thompsonq, L. Thompsonf, W.H. Trzaskas, M. Tippmannn, A. Tonazzoc, K. Urbanczykj, G. Vasseurh, A. Williamst, J. Wintern, K. Wojtuszewskaj, M. Wurmn, A. Zalewskay, M. Zampaoloc, M. Zitoh

Rare event search experiments, such as those searching for dark matter and observations of neutrinoless double beta decay, require ultra low levels of radioactive background for unmistakable identification. In order to reduce the radioactive background of detectors used in these types of event searches, low background photosensors are required, as the physical size of these detectors become increasing larger, and hence the number of such photosensors used also increases rapidly. Considering that most dark matter and neutrinoless double beta decay experiments are turning towards using noble liquids as the target choice, liquid xenon and liquid argon for instance, photosensors that can work well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed specifically for use in ultra low background experiments operating at cryogenic temperatures. It is based on the proven photocathode plus silicon photomultiplier (SiPM) hybrid technology and consists of very few other, but also ultra radio-pure, materials like fused silica and silicon for the SiPM. The introduction of the SiGHT concept, as well as a feasibility study for its production, is reported in this paper.

Projects attempting the direct detection of WIMP dark matter share the common problem of eliminating sources of background or using techniques to distinguish background events from true signals. Although experiments such as DarkSide have achieved essentially background free exposures through careful choice of materials and application of efficient veto techniques, there will still be a high burden of proof to convince the greater scientific community when a discovery is claimed. A directional signature in the data would provide extremely strong evidence to distinguish a true WIMP signal from that of an isotropic background. Two-phase argon time projection chambers (TPCs) provide an experimental apparatus which can both be scaled to the ton-scale size required to accommodate the low cross-section expected for WIMP interactions and have an anisotropy that could be exploited to evaluate the polar angles of the resulting nuclear recoils from WIMP collisions with target nuclei. Our studies show that even a modest resolution in the polar angle reconstruction would offer a powerful tool to detect a directional signature. In this contribution, the status of the ReD experiment, which is under construction at Naples University, will be also shown. The aim of the project is to assess and enhance the directionality of two-phase argon TPCs. ReD will use a small TPC exposed to a beam of mono-energetic neutrons to study the so called “columnar recombination” in liquid argon. This development could have high impact on the future experiments in the field, opening up the potential to find conclusive evidence for dark matter or disprove the WIMP hypothesis at and above the mass range explored by planned accelerator experiments.

N. Abgrall22, A. Aduszkiewicz23, B. Andrieu11, T. Anticic13, N. Antoniou18, J. Argyriades22, A. G. Asryan15, B. Baatar9, A. Blondel22, J. Blumer5, L. Boldizsar10, A. Bravar22, J. Brzychczyk8, A. Bubak12 S. A. Bunyatov9, K.-U. Choi12, P. Christakoglou18, P. Chung16, J. Cleymans1, D. A. Derkach15, F. Diakonos18, W. Dominik23, J. Dumarchez11, R. Engel5, A. Ereditato20, G. A. Feofilov15, Z. Fodor10, A. Ferrero22, M. Gaździcki17,21, M. Golubeva6, K. Grebieszkow24, A. Grzeszczuk12, F. Guber6, T. Hasegawa7, A. Haungs5, S. Igolkin15, A. S. Ivanov15, A. Ivashkin6, K. Kadija13, N. Katrynska8, D. Kielczewska23, D. Kikola24, J. Kisiel12 T. Kobayashi7, V. I. Kolesnikov9, D. Kolev4, R. S. Kolevatov15, V. P. Kondratiev15, S. Kowalski12 A. Kurepin6, R. Lacey16, A. Laszlo10, V. V. Lyubushkin9, Z. Majka8, A. I. Malakhov9, A. Marchionni2, A. Marcinek8, I. Maris5 V. Matveev6, G. L. Melkumov9, A. Meregaglia2, M. Messina20, P. Mijakowski14, M. Mitrovski21, T. Montaruli18,∗, St. Mrowczynski17, S. Murphy22, T. Nakadaira7, P. A. Naumenko15, V. Nikolic13, K. Nishikawa7, T. Palczewski14, G. Palla10, A. D. Panagiotou18, W. Peryt24, R. Planeta8, J. Pluta24, B. A. Popov9, M. Posiadala23, P. Przewlocki14, W. Rauch3, M. Ravonel22, R. Renfordt21, D. Rohrich19, E. Rondio14, B. Rossi20, M. Roth5, A. Rubbia2, M. Rybczynski17, A. Sadovsky6, K. Sakashita7, T. Schuster21, T. Sekiguchi7, P. Seyboth17, M. Shibata7, A. N. Sissakian9, E. Skrzypczak23, M. Slodkowski24, A. S. Sorin9, P. Staszel8, G. Stefanek17, J. Stepaniak14, C. Strabel2, H. Stroebele21, T. Susa13, I. Szentpetery10, M. Szuba24, M. Tada7, A. Taranenko16, R. Tsenov4, R. Ulrich5, M. Unger5, M. Vassiliou18, V. V. Vechernin15, G. Vesztergombi10, Z. Wlodarczyk17, A. Wojtaszek17, W. Zipper12

In this report we present simulated event numbers, for various MC generators, for pion production in $\nu_{\mu}$ CC reactions on $\nucl{16}{O}$. For the simulation we used four different neutrino interaction generators: GENIE, FLUKA, NEUT, and NuWro, as proposed during the 45th Karpacz Winter School on neutrino interactions. First we give a brief outline of the theoretical models relevant to pion production. We then present results, in the form of tables showing the occupancy of primary and final state pion topologies, for all the generated samples. Finally we compare the results from the different generators and draw conclusions about the similarities and differences. For some of the generators we explore the effect of varying the axial mass parameter or the use of a different nuclear model.

In this report we present simulated event numbers, for various MC generators, for pion production in � � CC reactions on 16 O. For the simulation we used four different neutrino interaction generators: GENIE, FLUKA, NEUT, and NuWro, as proposed during the 45th Karpacz Winter School on neutrino interactions [1]. First we give a brief outline of the theoretical models relevant to pion production. We then present results, in the form of tables showing the occupancy of primary and final state pion topologies, for all the generated samples. Finally we compare the results from the different generators and draw conclusions about the similarities and differences. For some of the generators we explore the effect of varying the axial mass parameter or the use of a different nuclear model.

In this report we present simulated event numbers, for various MC generators, for pion production in $ν_μ$ CC reactions on $\nucl{16}{O}$. For the simulation we used four different neutrino interaction generators: GENIE, FLUKA, NEUT, and NuWro, as proposed during the 45th Karpacz Winter School on neutrino interactions. First we give a brief outline of the theoretical models relevant to pion production. We then present results, in the form of tables showing the occupancy of primary and final state pion topologies, for all the generated samples. Finally we compare the results from the different generators and draw conclusions about the similarities and differences. For some of the generators we explore the effect of varying the axial mass parameter or the use of a different nuclear model.

he physics program of the NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) experiment at the CERN SPS consists of three subjects. In the first stage of data taking (2007-2009) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger and KASCADE) experiments will be performed. In the second stage (2009-2010) hadron production in proton-proton and proton-nucleus interactions needed as reference data for a better understanding of nucleus-nucleus reactions will be studied. In the third stage (2009-2013) energy dependence of hadron production properties will be measured in p+p, p+Pb interactions and nucleus-nucleus collisions, with the aim to identify the properties of the onset of deconfinement and find evidence for the critical point of strongly interacting matter. The NA61 experiment was approved at CERN in June 2007. The first pilot run was performed during October 2007. Calibrations of all detector components have been performed successfully and preliminary uncorrected spectra have been obtained. High quality of track reconstruction and particle identification similar to NA49 has been achieved. The data and new detailed simulations confirm that the NA61 detector acceptance and particle identification capabilities cover the phase space required by the T2K experiment. This document reports on the progress made in the calibration and analysis of the 2007 data.

Results in experimental study of shortwave radiation of interstellar absorption region with rocket mounted gamma and X-ray telescopes

Results in experimental study of shortwave radiation of interstellar absorption region with rocket mounted gamma and X-ray telescopes