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At least 595 records · Page 33

Recent results from ArgoNeuT and status of MicroBooNE

Liquid Argon Time Projection Chambers (LArTPCs) are a novel detector technology for neutrino detection experiments. Their fine granularity combined with calorimetric capabilities allows for precision measurements that will answer the outstanding questions about the role of neutrinos in the Standard Model of Particle physics and beyond it. Here, we discuss the development effort underway in the framework of the US based LArTPC program, which ties improving the reach of the technology with relevant physics measurements of beam neutrinos at Fermilab. Examples of experiments in this program are ArgoNeuT which ran on the NuMI beam line and acquired 1.35×10{sup 20} POT and MicroBooNE which is set to run on the Booster neutrino beamline at the beginning of 2015. Recent results from the ArgoNeuT experiment will be discussed as well as the status and prospects for MicroBooNE.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Charged current inclusive measurements in MINERνA

MINERvA is a neutrino scattering experiment stationed in the high intensity NuMI beam line at Fermilab, designed to measure neutrino cross sections, final states and nuclear effects on a variety of targets in the few-GeV region to reduce systematic uncertainties in oscillation experiments and provide new understanding of the nucleus. Here we present the current MINERvA results for inclusive charged current neutrino and anti-neutrino scattering in the active region of the detector and different neutrino cross section ratios with different nuclear targets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

MINERνA charged current inclusive analysis

MINERνA is a few-GeV neutrino scattering experiment that has been taking data in the NuMI beam line at Fermilab since November 2009. The experiment will provide important inputs, both in support of neutrino oscillation searches and as a pure weak probe of the nuclear medium. For this, MINERvA employs a fine-grained detector, with an eight ton active target region composed of plastic scintillator and a suite of nuclear targets composed of helium, carbon, iron, lead and water placed upstream of the active region. We will describe the current status of the charged current inclusive analysis in plastic scintillator.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Experimental station for laser-based picosecond time-resolved x-ray absorption near-edge spectroscopy

We present an experimental station designed for time-resolved X-ray Absorption Near-Edge Spectroscopy (XANES). It is based on ultrashort laser-plasma x-ray pulses generated from a table-top 100 mJ-class laser at 10 Hz repetition rate. A high transmission (10%–20%) x-ray beam line transport using polycapillary optics allows us to set the sample in an independent vacuum chamber, providing high flexibility over a wide spectral range from 0.5 up to 4 keV. Some XANES spectra are presented, demonstrating 1% noise level in only ∼1 mn and ∼100 cumulated laser shots. Time-resolved measurements are reported, indicating that the time resolution of the entire experimental station is 3.3 ± 0.6 ps rms.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The Fermilab short-baseline neutrino program

The Fermilab short-baseline program is a multi-facetted one. Primarily it searches for evidence of sterile neutrinos as hinted at by the MiniBooNE and LSND results. It will also measure a whole suite of ν-Argon cross sections which will be very useful in future liquid argon long-baseline projects. The program is based on MicroBooNE, already installed in the beam line, the recently approved LAr1-ND and the future addition of the refurbished ICARUS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Radiation hardness assessment of the charge-integrating hybrid pixel detector JUNGFRAU 1.0 for photon science

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications in free electron lasers, particularly SwissFEL, and synchrotron light sources. JUNGFRAU is an automatic gain switching, charge-integrating detector which covers a dynamic range of more than 10{sup 4} photons of an energy of 12 keV with a good linearity, uniformity of response, and spatial resolving power. The JUNGFRAU 1.0 application-specific integrated circuit (ASIC) features a 256 × 256 pixel matrix of 75 × 75 μm{sup 2} pixels and is bump-bonded to a 320 μm thick Si sensor. Modules of 2 × 4 chips cover an area of about 4 × 8 cm{sup 2}. Readout rates in excess of 2 kHz enable linear count rate capabilities of 20 MHz (at 12 keV) and 50 MHz (at 5 keV). The tolerance of JUNGFRAU to radiation is a key issue to guarantee several years of operation at free electron lasers and synchrotrons. The radiation hardness of JUNGFRAU 1.0 is tested with synchrotron radiation up to 10 MGy of delivered dose. The effect of radiation-induced changes on the noise, baseline, gain, and gain switching is evaluated post-irradiation for both the ASIC and the hybridized assembly. The bare JUNGFRAU 1.0 chip can withstand doses as high as 10 MGy with minor changes to its noise and a reduction in the preamplifier gain. The hybridized assembly, in particular the sensor, is affected by the photon irradiation which mainly shows as an increase in the leakage current. Self-healing of the system is investigated during a period of 11 weeks after the delivery of the radiation dose. Annealing radiation-induced changes by bake-out at 100 °C is investigated. It is concluded that the JUNGFRAU 1.0 pixel is sufficiently radiation-hard for its envisioned applications at SwissFEL and synchrotron beam lines.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

A compact source for bunches of singly charged atomic ions

We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 10{sup 6} Mg{sup +} ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg{sup +} ions for sympathetic cooling of highly charged ions by laser-cooled {sup 24}Mg{sup +}.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Formation and annihilation of E4 centers in ZnO: Influence of hydrogen

Hydrothermally grown n-type ZnO bulk samples have been implanted with protons and deuterium ions to fluences in the range of 8 × 10{sup 10} to 8 × 10{sup 11 }cm{sup −2}. The implantations were performed at the temperature of 285 K, and the samples were then analyzed in-situ by deep level transient spectroscopy (DLTS) using a setup connected to the implanter beam line. The concentration of the so-called E4 center, having an apparent energy level at ∼0.57 eV below the conduction edge, is found to increase linearly with the ion fluence and the generation rate is proportional to the elastic energy deposition, as expected for a primary defect. Isothermal annealing of the E4 center at temperatures between 290 and 315 K reveals first-order kinetics with the activation energy of ∼0.6 eV. The annealing rate is strongly enhanced with increasing hydrogen fluence, and a model invoking migration of interstitial hydrogen and subsequent reaction with E4 exhibits close agreement with the experimental data. The rate of electron capture by E4 during the DLTS filling pulse depends on temperature, and it displays a thermal barrier of ∼0.15 eV. Most of these experimental results for E4 conform to the theoretically predicted properties of the oxygen vacancy (V{sub O}) and a tentative assignment of E4 to V{sub O} is made, corroborating previous suggestions in the literature. In particular, the 0.57 eV level is ascribed to the double donor state of V{sub O}.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

On compression and damage evolution in PTFE and PEEK

The well-known Taylor cylinder impact test, that follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, PTFE and PEEK. In previous work experiments and a model were developed to capture the deformation behavior of the rod after impact. A distinctive feature of these works was that a region in which both spatial and temporal variation of both longitudinal and radial deformation showed evidence of changes in phase within the material. This region is X-ray imaged in a range of impacted targets at the I13 Imaging and Coherence beam line at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. In conclusion, this shows the transit of damage from ductile to brittle failure results from previously undetected internal failure.

36 MATERIALS SCIENCE↗

Installation of a solid state neutral particle analyzer array on mega ampere spherical tokamak upgrade

A compact solid state neutral particle analyzer (SSNPA) diagnostic, previously installed at NSTX-U, has been moved to MAST-U and successfully operated in the first physics campaign (MU01). The SSNPA operates by detecting the flux of fast neutral particles produced by charge exchange (CX) reactions to diagnose the fast ion distribution. The diagnostic consists of three 16-channel sensors, which provide a radial view of the plasma and have a sightline intersection with the South–South neutral beam line. From this radial geometry, active CX signals from mostly trapped particles are observed. Each channel has a spatial resolution of 3–4 cm, a temporal resolution of 200 kHz, and an average pitch angle resolution of a few degrees. The three-sensor configuration allows for coarse energy resolution of the CX signals; each sensor sees similar sightlines but different filter thicknesses alter the energy cutoffs by known amounts. Experimental data show that all channels are collecting data as intended. The signal to noise ratio is typically around 15. Preliminary data analysis shows a correlation between the SSNPA signal and magnetohydrodynamic activity in the plasma as expected.

Instruments & Instrumentation↗

DIII-D research towards resolving key issues for ITER and steady-state tokamaks

The DIII-D research program is addressing key ITER research needs and developing the physics basis for future steady-state tokamaks. Pellet pacing edge-localized mode (ELM) control in the ITER configuration reduces ELM energy loss in proportion to 1/f pellet by inducing ELMs at up to 12× the natural ELM rate. Complete suppression of ELMs with resonant magnetic perturbations has been extended to the q 95 expected for ITER baseline scenario discharges, and long-duration ELM-free QH-mode discharges have been produced with ITER-relevant co-current neutral-beam injection (NBI) using external n = 3 coils to generate sufficient counter-I p torque. ITER baseline discharges at β N ~ 2 and scaled NBI torque have been maintained in stationary conditions for more than four resistive times using electron cyclotron current drive (ECCD) for tearing mode suppression and disruption avoidance; active tracking with steerable launchers and feedback control catch these modes at small amplitude, reducing the ECCD power required to suppress them. Massive high-Z gas injection into disruption-induced 300–600 kA 20MeV runaway electron (RE) beams yield dissipation rates ~10$\times$ faster than expected from e–e collisions and demonstrate the possibility of benign dissipation of such REs should they occur in ITER. Other ITER-related experiments show measured intrinsic plasma torque in good agreement with a physics-based model over a wide range of conditions, while first-time main-ion rotation measurements show it to be lower than expected from neoclassical theory. Core turbulence measurements show increased temperature fluctuations correlated with sharply enhanced electron transport when $∇T_e/T^{–1}_e$ exceeds a critical-gradient scale length. In H-mode, data show the pedestal height and width growing between ELMs with ∇P at the computed kinetic-ballooning limit, in agreement with the EPED model. Successful modification of a neutral-beam line to provide 5MW of adjustable off-axis injection has enabled sustained operation at βN ~ 3 with broader current and pressure profiles at higher q min than previously possible, though energy confinement is lower than expected. Overall, initial experiments aimed at developing integrated core and boundary solutions demonstrated heat flux reduction using enhanced edge radiation from neon injection and innovative divertor geometries (e.g. snowflake configuration).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Next generation HOM-damping

Research and development for superconducting radio-frequency cavities has made enormous progress over the last decades from the understanding of theoretical limitations to the industrial mass fabrication of cavities for large-scale particle accelerators. Key technologies remain hot topics due to continuously growing demands on cavity performance, particularly when in pursuit of high quality beams at higher beam currents or higher luminosities than currently achievable. This relates to Higher Order Mode (HOM) damping requirements. Meeting the desired beam properties implies avoiding coupled multi-bunch or beam break-up instabilities depending on the machine and beam parameters that will set the acceptable cavity impedance thresholds. The use of cavity HOM-dampers is crucial to absorb the wakefields, comprised by all beam-induced cavity Eigenmodes, to beam-dynamically safe levels and to reduce the heat load at cryogenic temperature. Cavity damping concepts may vary, but are principally based on coaxial and waveguide couplers as well as beam line absorbers or any combination. Next generation Energy Recovery Linacs and circular colliders call for cavities with strong HOM-damping that can exceed the state-of-the-art, while the operating mode efficiency shall not be significantly compromised concurrently. This imposes major challenges given the rather limited damping concepts. A detailed survey of established cavities is provided scrutinizing the achieved damping performance, shortcomings, and potential improvements. The scaling of the highest passband mode impedances is numerically evaluated in dependence on the number of cells for a single-cell up to a nine-cell cavity, which reveals the increased probability of trapped modes. This is followed by simulations for single-cell and five-cell cavities, which incorporate multiple damping schemes to assess the most efficient concepts. The usage and viability of on-cell dampers is elucidated for the single-cell cavity since it can push the envelope towards quasi HOM-free operation suited for next generation storage and collider rings. Geometrical end-cell shape alterations for the five-cell cavity with already efficient mode damping are discussed as a possibility to further lower specific high impedance modes. Lastly, the findings are eventually put into relation with demanding impedance instability thresholds in future collider rings.

43 PARTICLE ACCELERATORS↗

Developing LAr Scintillation Light Collection Ideas in the Short Baseline Neutrino Detector

Scintillation light is becoming the most rapidly developing feature of Liquid Argon Time Projection Chamber (LArTPC) neutrino detectors due to its capability to enhance and expand their physics reach traditionally based on charge readout. The SBND detector, set to be built on the Booster Neutrino Beam Line at Fermilab, is in a unique position to test novel liquid argon scintillation light readout systems in a detector with physics neutrino events. The different ideas under consideration by the collaboration are described, including an array of PMTs detecting direct light, SiPM coupled lightguide bars and a setup which uses PMTs/SiPMS and wavelength shifter covered reflector foils, as well as their respective strengths and physics foci and the benchmarks used to compare them.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The beam and detector of the NA62 experiment at CERN

NA62 is a fixed-target experiment at the CERN SPS dedicated to measurements of rare kaon decays. Such measurements, like the branching fraction of the K + → π + ν ν¯ decay, have the potential to bring significant insights into new physics processes when comparison is made with precise theoretical predictions. For this purpose, innovative techniques have been developed, in particular, in the domain of low-mass tracking devices. Detector construction spanned several years from 2009 to 2014. The collaboration started detector commissioning in 2014 and will collect data until the end of 2018. Furthermore, the beam line and detector components are described together with their early performance obtained from 2014 and 2015 data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

A new strips tracker for the upgraded ATLAS ITk detector

The ATLAS detector has been created and determined to function in the environment of the present Large Hadron Collider (LHC). At the next-generation tracking detector proposed for the High Luminosity LHC (HL-LHC), the so-called ATLAS Phase-II Upgrade, the fluences and radiation levels will be higher by as much as a factor of ten. The new sub-detectors must thus be faster, of larger area, more segmented and more radiation hard while the amount of inactive material should be minimized and the power supply to the front-end systems should be increased. For those reasons, the current inner tracker of the ATLAS detector will be fully replaced by an all-silicon tracking system that consists of a pixel detector at small radius close to the beam line and a large area strip tracker surrounding it. This report gives an overview of the design of the strip inner tracker (Strip ITk) and summarises the intensive R&D activities performed over the last years by the numerous institutes within the Strips ITk collaboration. These studies are accompanied with a strong prototyping effort to contribute to the optimisation of the Strip ITk's structure and components. This effort culminated recently in the release of the ATLAS Strips ITk Technical Design Report (TDR).

Si microstrip and pad detectors↗

Test and characterization of 400 Hamamatsu R5912-MOD photomultiplier tubes for the ICARUS T600 detector

ICARUS T600 will be operated as far detector of the Short Baseline Neutrino program at Fermilab (U.S.A.), which foresees three liquid argon time projection chambers along the Booster Neutrino Beam line to search for a LSND-like sterile neutrino signal. The detector employs 360 photomultiplier tubes, Hamamatsu model R5912-MOD, suitable for cryogenic applications. A total of 400 PMTs were procured from Hamamatsu and tested at room temperature to evaluate the performance of the devices and their compliance to detect the liquid argon scintillation light in the T600 detector. Furthermore 60 units were also characterized at cryogenic temperature, in liquid argon bath, to evaluate any parameter variation which could affect the scintillation light detection. All the tested PMTs were found to comply with the requirements of ICARUS T600 and a subset of 360 specimens was selected for the final installation in the detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Development of a FELIX based readout system for ITk strip hybrid module demonstrator for ATLAS Phase-II Upgrade

The Large Hadron Collider (LHC) will undergo a major upgrade around 2024 with a roughly tenfold increase in luminosity. It results in corresponding increases in particle rates and radiation doses that the current ATLAS Inner Tracking Detector cannot cope with. Therefore the ATLAS experiment will build a new all-silicon tracking system called the ITk (Inner Tracker) that includes an inside pixel detector close to the beam line and a strip detector in outside layer. Meanwhile the ATLAS experiment will adopt the Front-End Link eXchange (FELIX) system as the interface between the data acquisition and front-end electronics for all sub-detectors in the Phase II Upgrade. In this contribution, we present a prototype of FELIX based readout system for the strip hybrid module. Its hardware, firmware and software GUI application will be discussed, as well as integration test results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Active Region Extent Assessment with X-rays (AREA-X)

The development of semiconductor sensors for new particle tracking detectors places increasing limits on sensor characteristics such as uniformity, size and shape of inefficient areas and size of active compared to inactive sensor areas. Accurately assessing these relatively subtle effects requires either measurements in particle beams or the modification of samples to be used in dedicated laser test setups. Active Region Extent Assessment with X-rays (AREA-X) has been developed as an alternative method for the fast, efficient and precise study of the active area of a semiconductor sensor. It uses a monochromatic, micro-focused X-ray beam with a 10–20 keV energy range as provided by several synchrotron beam lines and uses the photo current induced in the sensor to measure the depth of the responsive sensor volume. It can be used to study local inhomogeneities or inefficiencies, the overall extent of the active sensor volume and its shape and its localised application, which makes the need to gather statistics over a large area unnecessary, allowing for fast readout, which enables studies of the sensor behaviour at a range of external parameters, e.g. temperature or applied bias voltage. This paper presents the measurement concept and technical setup of the measurement, results from initial measurements as well as capabilities and limitations of the method.

47 OTHER INSTRUMENTATION↗