Search

PURPOSE: This study aimed to assess the effectiveness of the “modified graded motor imagery” (mGMI) protocol as a rehabilitative treatment of musician’s focal dystonia (MFD). METHODS: Six musicians with MFD (age 43.83±17.24 yrs) performed the home-based mGMI protocol (laterality training, imagined hand movements and visual mirror feedback) once a day for 4 weeks. The mMGI protocol was designed to sequentially activate cortical motor networks and improve cortical organization. Subjects were evaluated before and after treatment with the dystonia evaluation scale (DES), arm dystonia disability scale (ADDS), Tubiana-Chamagne scale (TCS), and performing scale (PS). RESULTS: All participants were compliant with the mGMI treatment protocol without any adverse events. A significant improvement was measured in ADDS (p=0.047) and TCS scores (p=0.014) but not in DES (p=0.157). The severity of MFD decreased from moderate to mild in four patients. After mGMI treatment, all musicians were able to play easy pieces (TCS: median 3.5, IR 3.5–4). CONCLUSION: The findings from this pilot study suggest that home-based mGMI treatment is a feasible and promising rehabilitative approach for patients with mild to moderate MFD.

Background: $\ensuremath{\beta}$-decay spectroscopy provides valuable information on exotic nuclei and a stringent test for nuclear theories beyond the stability line.Purpose: To search for new $\ensuremath{\beta}$-delayed protons and $\ensuremath{\gamma}$ rays of $^{25}\mathrm{Si}$ to investigate the properties of $^{25}\mathrm{Al}$ excited states.Method: $^{25}\mathrm{Si}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$ decays were measured by using the Gaseous Detector with Germanium Tagging system at the National Superconducting Cyclotron Laboratory. The protons and $\ensuremath{\gamma}$ rays emitted in the decay were detected simultaneously. A Monte Carlo method was used to model the Doppler broadening of $^{24}\mathrm{Mg}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray lines caused by nuclear recoil from proton emission. Shell-model calculations using two newly developed universal sd-shell Hamiltonians were performed.Results: The most precise $^{25}\mathrm{Si}$ half-life to date has been determined. A new proton branch at 724(4) keV and new proton-$\ensuremath{\gamma}$-ray coincidences have been identified. Three $^{24}\mathrm{Mg}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray lines and eight $^{25}\mathrm{Al}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray lines are observed for the first time in $^{25}\mathrm{Si}$ decay. The first measurement of the $^{25}\mathrm{Si}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$-ray intensities through the $^{25}\mathrm{Al}$ unbound states is reported. All the bound states of $^{25}\mathrm{Al}$ are observed to be populated in the $\ensuremath{\beta}$ decay of $^{25}\mathrm{Si}$. Several inconsistencies between the previous measurements have been resolved, and new information on the $^{25}\mathrm{Al}$ level scheme is provided. An enhanced decay scheme has been constructed and compared to the mirror decay of $^{25}\mathrm{Na}$ and the shell-model calculations.Conclusions: The measured excitation energies, $\ensuremath{\gamma}$-ray and proton branchings, log $ft$ values, and Gamow-Teller transition strengths for the states of $^{25}\mathrm{Al}$ populated in the $\ensuremath{\beta}$ decay of $^{25}\mathrm{Si}$ are in good agreement with the shell-model calculations, offering gratifyingly consistent insights into the fine nuclear structure of $^{25}\mathrm{Al}$.

Type-I x-ray bursts can reveal the properties of an accreting neutron star system when compared with astrophysics model calculations. However, model results are sensitive to a handful of uncertain nuclear reaction rates, such as ^{22}Mg(α,p). We report the first direct measurement of ^{22}Mg(α,p), performed with the Active Target Time Projection Chamber. The corresponding astrophysical reaction rate is orders of magnitude larger than determined from a previous indirect measurement in a broad temperature range. Our new measurement suggests a less-compact neutron star in the source GS1826-24.

The three-dimensional reconstruction of particle tracks in a time projection chamber is a challenging task that requires advanced classification and fitting algorithms. In this work, we have developed and implemented a novel algorithm based on the Random Sample Consensus Model (RANSAC). The RANSAC is used to classify tracks including pile-up, to remove uncorrelated noise hits, as well as to reconstruct the vertex of the reaction. The algorithm, developed within the Active Target Time Projection Chamber (AT-TPC) framework, was tested and validated by analyzing the 4 He+ 4 He reaction. Results, performance and quality of the proposed algorithm are presented and discussed in detail.

The Active-Target Time Projection Chamber (AT-TPC) was recently built and commissioned at the National Superconducting Cyclotron Laboratory at Michigan State University. This gas-filled detector uses an active-target design where the gas acts as both the tracking medium and the reaction target. Operating inside a 2T solenoidal magnetic field, the AT-TPC records charged particle tracks that can be reconstructed to very good energy and angular resolutions. The near- 4 π solid angle coverage and thick target of the detector are well-suited to experiments with low secondary beam intensities. In this paper, the design and instrumentation of theAT-TPC are described along with the methods used to analyze the data it produces. A simulation of the detector’s performance and some results from its commissioning with a radioactive 46 Ar beam are also presented.

The Gaseous Detector with Germanium Tagging (GADGET) is a new detection system devoted to the measurement of weak, low-energy β -delayed proton decays relevant for nuclear astrophysics studies. It is comprised of a new gaseous Proton Detector equipped with a Micromegas readout for charged particle detection, surrounded by the existing Segmented Germanium Array (SeGA) for the high-resolution detection of the prompt γ -rays. In this work we describe in detail for the first time the design, construction, and operation of the GADGET system, including performance of the Proton Detector. We present the results of a recent commissioning experiment performed with 25 Si beam at the National Superconducting Cyclotron Laboratory (NSCL). GADGET provided low-background, low-energy β -delayed proton detection with efficiency above 95%, and relatively good efficiency for proton-gamma coincidences (2.7% at 1.37 MeV).

We discuss the operational principle and performance of new micro-pattern gaseous detectors based on the multi-layer Thick Gaseous Electron Multiplier (M-THGEM) concept coupled to a needle-like anode. The new gas avalanche structure aims at high-gain operation in nuclear physics and nuclear astrophysics applications with radioactive isotope beams. It is thereafter named TIP-HOLE gas amplifier, and consists of a THGEM or a two-layers M-THGEM mounted in a WELL configuration. The avalanche electrodes are collected by thin conductive needles (with up to a few ten um radius and a height of 100 um), located at the center of the hole and acting as point-like anode. The bottom area of the needle may be surrounded by a cylindrical cathode strip in order to increase the electron collection efficiency. The electric field lines from the drift region above the M-THGEM are focused into the holes, and then forced to converge on the needle tip. An extremely high field is reached at the top of the needle, creating a point-like avalanche process. Stable, high-gain operations in a wide range of pressures may be achieved at relatively low operational voltage, even in pure quencher gas at atmospheric pressure (e.g. pure isobutene). The TIP-HOLE structure may be produced by the innovative scalable additive manufacturing technology for large-area, multiple-layer printed circuit boards, recently developed by the UHV technology company (USA) and discussed for the first time in this work., Comment: 8 pages, 6 figures. submitted to JINST

The performance of a novel tracking detector developed for the focal plane of the NSCL/FRIB S800 magnetic spectrometer is presented. The detector comprises a large-area drift chamber equipped with a hybrid Micro-Pattern Gaseous Detector (MPGD)-based readout. The latter consists of a position-sensitive Micromegas detector preceded by a two-layer M-THGEM multiplier as a pre-amplification stage. The signals from the Micromegas readout are processed by a data acquisition system based on the General Electronics for TPC (GET). The drift chamber has an effective area of around 60x30 cm^2, which matches to the very large acceptance of the S800 spectrometer. This work discusses in detail the results of performance evaluation tests carried out with a low-energy alpha-particles source and with high-energy heavy-ion beams with the detector installed at the S800 focal plane. In this latter case, the detector was irradiated with a 150 MeV/u 78Kr36+ beam as well as a heavy-ion fragmentation cocktail beam produced by the 78Kr36+ beam impinging on a thin beryllium target. Sub-millimeter position resolution is obtained in both dispersive and non-dispersive directions., Comment: 13 pages, 13 figures

Many nuclear structure studies are presently performed with secondary radioactive beams to explore the nuclear chart far from stability. This entails a large decrease of available intensities, as compared to stable beam experiments, even with the highest power primary beam accelerators. To compensate for this intensity loss, thick targets and high detection efficiency are needed. Using secondary beams implies a change from direct kinematics to inverse kinematics: the target becomes the light reaction partner and the beam the heavy reaction partner. In quasi-elastic processes, the light reaction partner carrying most of the information emerges with very low recoil energy. In these conditions Time Projections Chambers (TPCs) filled with a gas that serves as both target and tracking medium (Active Target) have very unique properties that mitigate these difficulties. By construction, a TPC has a solid angle coverage of $ 4\pi$ , and even short tracks of low energy particles can be precisely measured if the readout has a high enough granularity. Due to the reaction characteristics large dynamics of the electronics and gas multipliers are needed, and specific data analysis methods of the 3-dimensional tracks have to be developed.

We describe a new micro-pattern gas detector structure comprising a multi-layer hole-type multiplier (M-THGEM) combined with two in-built electrode meshes: the Multi-Mesh THGEM-type multiplier (MM-THGEM). Suitable potential differences applied between the various electrodes provide an efficient collection of ionization electrons within the MM-THGEM holes and a large charge avalanche multiplication between the meshes. Different from conventional hole-type multipliers (e.g. Gas Electron Multipliers - GEMs, Thick Gas Electron Multipliers - THGEMs, etc.), which are characterized by a variable (dipole-like) field strength inside the avalanche gap, electrons in MM-THGEMs are largely multiplied by a strong uniform field established between the two meshes, like in the parallel-plate avalanche geometry. The presence of the two meshes within the holes allows for the trapping of a large fraction of the positive ions that stream back to the drift region. A gas gain above 10^5 has been achieved for single photo-electron detection with a single MM-THGEM in Ar/(10%)CH4 and He/(10%)CO2, at standard conditions for temperature and pressure. When the MM-THGEM is coupled to a conventional THGEM and used as first cascade element, the maximum achievable gains reach values above 10^6 in He/(10%)CO2, while the IBF approaches of 1.5% in the case of optimum detector-bias configuration. This IBF value is several times lower compared to the one obtained by a double GEM/THGEM detector (5-10%), and equivalent to the performance attained by a Micromegas detector., 11 pages, 8 figures. Submitted to JINST

Sustainable reservoir use is globally threatened by sedimentation. It has been generally recognized that inadequate consideration of reservoir sedimentation has caused the worldwide decline of net storage. Numerical models are useful tools to simulate sedimentation processes and can be used to derive efficient counter-measures and sediment management strategies. They can be applied to both existing and potential future reservoirs to predict long-term sedimentation. In this study, an application of a simple, robust, and stable numerical 1D model to Gebidem reservoir in Switzerland accompanied by field measurements is presented. It focusses on seasonal and large-scale reservoir sedimentation processes that occur continuously throughout the whole deposition season, while episodic events like turbidity currents are not taken into account. The model simulates both the delta formation of coarse sediments and the lake-wide sedimentation from homopycnal flows. The model is used to assess the effects and significance of varying boundary conditions like inflow, suspended sediment concentration, particle size distribution (PSD), or reservoir operation. It will be demonstrated that future reservoir operation and PSD are as important as future runoff evolution. Based on these findings, implications on future reservoir operation, also considering climate change, are discussed. Finally, an outlook on pending research topics is given., Sustainability, 10 (9), ISSN:2071-1050

Shell closures and their associated magic numbers of nucleons provide a unique means for studying the structure of exotic nuclei far from stability. An experiment was recently performed at the National Superconducting Cyclotron Laboratory to measure resonant elastic proton scattering on $^{46}$Ar in inverse kinematics in the region containing isobaric analogue states of $^{47}$Ar, an N=29 nucleus with one neutron above the N=28 shell closure. Four candidate resonances were observed: one corresponding to the 3/2− ground state of $^{47}$Ar, another corresponding to its 1/2− first excited state, and two that likely correspond to states in the $^{47}$K compound nucleus. The observed properties of the ground state resonance were compatible with values from the literature, but a significantly lower spectroscopic factor was found for the 1/2− state resonance.

In view of a possible application as a charge-particle track readout for an Active-Target Time Projection Chamber (AT-TPC), the operational properties and performances of a hybrid Micro-Pattern Gaseous Detector (MPGD) were investigated in pure low-pressure Hydrogen (H2) and Helium (He). The detector consists of a MICROMEsh GAseous Structure (MICROMEGAS) coupled to a two-cascade THick Gaseous Electron Multiplier (THGEM) as a pre-amplification stage. This study reports the effective gain dependence of the hybrid-MPGD at relevant pressure (in the range of 200-760 torr) for different detector arrangements. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particularly for applications of MPGD end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics.

We describe a novel gaseous detector concept for heavy-ion tracking and imaging: the Optical Parallel-Plate Avalanche Counter (O-PPAC). The detector consists of two thin parallel-plate electrodes separated by a small (typically 3 mm) gap filled with low-pressure scintillating gas (i.e. CF4). The localization of the impinging particles is achieved by recording the secondary scintillation, created during the avalanche processes within the gas gap, with dedicated position-sensitive optical readouts. The latter may comprise arrays of collimated photo-sensors (e.g. SiPMs) that surround the PPAC effective area. We present a systematic Monte Carlo simulation study used to optimize the geometry of the OPPAC components, including SiPMs effective area, collimator dimensions, and operational conditions. It was found that the optimal design for 10x10 cm^2 OPPAC detector comprises four arrays, each of them counting a total of 15-20 individual photo-sensors. This configuration provides a localization capability with a resolution below 1 mm and good response uniformity. An experimental investigation successfully demonstrated the proof of principle stage of an O-PPAC prototype equipped with a single array of 10 photo-sensors, separated by 6 mm. The performance of the prototype was investigated with an LED light, under 10-,12-C beam irradiation, and with a low-intensity 241-Am alpha-particle source. The experimental data obtained with the prototype is compared to the results obtained by systematic Monte Carlo simulations., Comment: 21 pages, 17 Figures. Submitted to JINST

The Active Target Time Projection Chamber (AT-TPC) project at the National Superconducting Cyclotron Laboratory (NSCL) is a novel Active Target designed to study nuclear reactions induced by low-intensity exotic beams. The AT-TPC acts as a tracking medium and target at the same time, providing excellent angular (1 ° ) and energy resolution (3% FWHM) and high luminosity . The AT-TPC offers a broad range of applications within the low-energy nuclear physics domain. Resonant scattering and transfer reactions are typically performed with Active Targets using beams with energies spanning from 1 to 10 A MeV and with intensities as low as 100 pps. The AT-TPC is also a promising tool for experiments where the observables of interest require higher beam energies (above 100 A MeV ). In particular, inelastic scattering reactions on light targets, where the recoil particle has a very low kinetic energy (less than 1 MeV), can be performed with such a device. In this work, we discuss aspects of the AT-TPC experimental program, focusing on experiments that leverage the outstanding capabilities this detector offers. In addition, we introduce a conceptual design for a new Time Projection Chamber detector for specific measurements of reactions using special gases as targets.

The present paper gives an overview of the status of an ongoing project aiming at the development of a fast neutron imaging system for investigating two-phase flows primarily in the context of nuclear fuel bundle development. Other potential subjects for investigations include steam explosions for severe accident research and liquid metal two-phase flows for Gen IV reactor systems. The project is carried out in the form of a feasibility study that should enable estimation of the ultimate imaging capabilities achievable. The imaging system used in the feasibility study consists of a compact, deuterium–deuterium fusion based neutron generator and dedicated imaging detectors. For the latter two promising concepts are developed in parallel: one is based on an array of plastic scintillators coupled with silicon photomultipliers, the other on a special multi-foil recoil proton converter coupled to a position sensitive charge readout using a micro pattern gas detector.

The operating principle and performances of the Multi-layer Thick Gaseous Electron Multiplier (M-THGEM) are presented. The M-THGEM is a novel hole-type gaseous electron multiplier produced by multi-layer printed circuit board technology; it consists of a densely perforated assembly of multiple insulating substrate sheets (e.g., FR-4), sandwiched between thin metallic-electrode layers. The electron avalanche processes occur along the successive multiplication stages within the M-THGEM holes, under the action of strong dipole fields resulting from the application of suitable potential differences between the electrodes. The present work focuses on the investigation of two different geometries: a two-layer M-THGEM (either as single or double-cascade detector) and a single three-layer M-THGEM element, tested in various low-pressure He-based gas mixtures. The intrinsically robust confinement of the avalanche volume within the M-THGEM holes provides an efficient reduction of the photon-induced secondary effects, resulting in a high-gain operation over a broad pressure range, even in pure elemental gas. The operational principle, main properties (maximum achievable gain, long-term stability, energy resolution, etc.) under different irradiation conditions, as well as capabilities and potential applications are presented and discussed.

Reactions in inverse kinematics close to the Coulomb barrier offer unique opportunities to study exotic nuclei, but they are plagued by the difficulty to efficiently and precisely measure the characteristics of the emerging particles. The Active Target Time Projection Chamber (AT-TPC) offers an elegant solution to this dilemma. In this device, the detector gas of the time projection chamber is at the same time the target in which nuclear reactions take place. The use of this new paradigm offers several advantages over conventional inert target methods, the most significant being the ability to increase the luminosity of experiments without loss of resolution. The AT-TPC and some results obtained on resonant α scattering to explore the clustering properties of neutron-rich nuclei are presented, as well as fusion cross section results using a 10 Be radioactive beam. In addition, the first re-accelerated radioactive beam experiment using the fully commissioned ReA3 linac was conducted recently at the NSCL with the AT-TPC, where proton resonant scattering of a 4.6 MeV/u 46 Ar beam was used to measure the neutron single-particle strength in 47 Ar.

BACKGROUND PSA blood test and other present screening tools fail to provide the required sensitivity and specificity and, at early stages, lack correlation with tumor grade, volume, and location. Thus alternative approaches are highly desired. We present and assess a novel method for PCa detection, grading, volume evaluation and tumor location, based on non-invasive zinc concentration mapping in the gland by means of a dedicated rectal probe. METHODS Zinc-concentration values measured in histologically examined tissue fragments from needle biopsy of 598 patients were analyzed. They were used to generate computer simulated zinc-concentration maps, further analyzed with image-processing tools. The tumor detection performances versus Gleason grade were assessed. RESULTS A significant increase of zinc depletion with increasing Gleason pattern (grade) classification was established. Tumor detection performance in zinc-concentration maps progressively improves with the cancer's first component score. Reliable information on the location, size and Gleason-grade combination of the lesion can be extracted for clinically relevant volumes. CONCLUSIONS Zinc depletion in the prostate peripheral zone is the basis for a novel, non-invasive PCa detection, localization, volume evaluation and grading method. Its realization and application as a pre-biopsy and pre-treatment examination, or a follow-up tool, relies on the development of a dedicated transrectal probe. It should have significant impact on biopsy effectiveness, point at a possible extraprostatic extension and provide critical data for focal treatment. The information on tumor grade and distribution may have an important impact on disease management. Prostate 70: 1701–1708, 2010. © 2010 Wiley-Liss, Inc.

The present work deals with the analysis of prostatic-zinc-concentration images. The goal is to evaluate potential clinically relevant information that can be extracted from such images. In the absence of experimental images, synthetic ones are produced from clinically measured zinc-concentration distributions in certified benign and cancerous tissue samples, classified by the lesion grade. We describe the method for producing the images and model the effect of counting statistics noise. We present in detail the image analysis, which is based on a combination of standard image processing and segmentation tools, optimized for this particular application. The information on lowest zinc value obtained from the image analysis is translated to clinical data such as tumour presence, location, size and grade. Their confidence is evaluated with the help of standard statistical tools such as receiver operating characteristic analysis. The present work predicts a potential for detecting small prostate-cancer lesions, of grade (4+3) and above, with very good specificity and sensitivity. The present analysis further provides data on the pixel size and image counting statistics requested from the trans-rectal probe that will record in vivo prostatic-zinc maps in patients.

We study the performance of single- and double- THick Gas Electron Multiplier (THGEM) detectors in pure Hydrogen and Deuterium at low pressures, in the range of 100-450 Torr. The effect of the pressure on the maximum achievable gain, ion-back flow and long-term gain stability are investigated for single and double cascade detectors. In particular, it was found that maximum achievable gains above 10^4, from single-photoelectrons avalanche, can be achieved for pressures of 200 Torr and above; for lower pressure the gains are limited by avalanche-induced secondary effects to a values of around 103. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particular for applications of THGEM end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics., Published in JINST; 9 pages, 7 figures

The study of low-energy reactions with radioactive-ion beams has been greatly enhanced by the recent use of active-target detectors, which have high efficiency and low thresholds to detect low-energy charged-particle decays. Both of these features have been used in experiments with the Prototype Active-Target Time-Projection Chamber to study α -cluster structure in unstable nuclei and 3-body charged-particle decays after implantation. Predicted α -cluster structures in 14 C were probed using resonant α scattering and the nature of the 3- α breakup of the 0 2 + Hoyle state in 12 C after the beta decay of 12 N and 12 B was studied. These experiments used in-flight radioactive-ion beams that were produced using the dual superconducting solenoid magnets TwinSol at the University of Notre Dame. Preliminary results from these experiments as well as the development of future radioactive beams to be used in conjunction with the PAT-TPC are presented.

We present our studies of prostatic Zn concentration measurements, carried out in the light of a novel prostate cancer (CAP) diagnosis method proposed by us. The method is based on in vivo prostatic Zn mapping by XRF trans-rectal probe. We report on the extensive clinical studies, intended to assess the validity of the novel proposed diagnostic method. Zn content was measured in vitro in needle-biopsy samples from several hundreds of patients, and was correlated with histological findings and other patient parameters. For this purpose, a technique of absolute Zn content determination in approximately 1mm(3) fresh tissue samples by XRF was developed. The experimental details and the main clinical-evaluation results are presented. We further outline the suggested design of the XRF trans-rectal probe for an efficient in vivo detection and mapping of the Zn fluorescence radiation from the prostate through the rectal wall. Laboratory phantom studies, a preliminary design concept and its expected performance are also reported.

The Active Target Time Projection Chamber (AT-TPC) project at the NSCL (National Superconducting Cyclotron Laboratory, Michigan State University) is a novel active target detector tailored for low-energy nuclear reactions in inverse kinematics with radioactive ion beams. The AT-TPC allows for a full three dimensional reconstruction of the reaction and provides high luminosity without degradation of resolution by the thickness of the target. Since all the particles (and also the reaction vertex) are tracked inside the detector, the AT-TPC has full 4π efficiency. The AT-TPC can operate under a magnetic field (2 T) that improves the identification of the particles and the energy resolution through the measurement of the magnetic rigidity. Another important characteristic of the AT-TPC is the high-gain operation achieved by the hybrid thick Gas Electron Multipliers (THGEM)-Micromegas pad plane, that allow operation also in pure elemental gas. These two features make the AT-TPC a unique high resolution spectrometer with full acceptance for nuclear physics reactions. This work presents an overview of the project, focused on the data analysis and the development of new micro-pattern gas detectors.

Recently, a new detector concept, for combined imaging and spectroscopy of fast-neutrons and gamma was presented. It encompasses a liquid-xenon (LXe) converter-scintillator coupled to a UV-sensitive gaseous Thick Gas Electron Multiplier (THGEM)-based imaging photomultiplier (GPM). In this work we present and discuss the results of a systematic computer-simulation study aiming at optimizing the type and performance of LXe converter. We have evaluated the detector spectral response, detection efficiency and spatial resolution for gamma-rays and neutrons in the energy range of 2-15 MeV for 50 mm thick converters consisting of plain LXe volume and LXe-filled capillaries, of Teflon, Polyethylene or hydrogen-containing Teflon (Tefzel). Neutron detection efficiencies for plain LXe, Teflon-capillaries and Tefzel-capillaries converters were about 20% over the entire energy range. In polyethylene capillaries converters the neutron detection efficiency was about 10% at 2 MeV and increased up to about 20% at 14 MeV. Detection efficiencies of gammas in Teflon, Tefzel and polyethylene converters were ~35%. The plain-LXe converter provided the highest gamma-ray detection efficiency, of ~40-50% for 2-15 MeV energy range. Optimization of LXe-filled Tefzel capillary dimensions resulted in spatial resolution of ~1.5mm (FWHM) for neutrons and up to 3.5 mm (FWHM) for gamma-rays. Simulations of radiographic images of various materials using two discrete energy gamma-rays (4.4 MeV and 15.1 MeV) and neutrons in broad energy range (2-10 MeV) were performed in order to evaluate the potential of elemental discrimination., 29 pages, 17 figures

We briefly present the principal properties of THGEM detectors, in standard and in noble gases (Xe, Kr, Ar and Ne), and shortly discuss their potential applications in accelerator- and non-accelerator-based experiments. UV-photon imaging in RICH, tracking of ionizing particles, large-volume TPCs for rare-events, sampling elements in digital calorimetry, ionization and scintillation recording from noble-liquid detectors, X-ray and neutron radiography etc.

We have demonstrated the feasibility of performing high-frame-rate, fast neutron radiography of air–water two-phase flows in a thin channel with rectangular cross section. The experiments have been carried out at the accelerator facility of the Physikalisch-Technische Bundesanstalt. A polychromatic, high-intensity fast neutron beam with average energy of 6 MeV was produced by 11.5 MeV deuterons hitting a thick Be target. Image sequences down to 10 ms exposure times were obtained using a fast-neutron imaging detector developed in the context of fast-neutron resonance imaging. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two phase flow parameters like the volumetric gas fraction, bubble size and mean bubble velocities have been measured. The first results are promising, improvements for future experiments are also discussed.

We present the results of our recent studies on a cold-neutron imaging detector prototype based on THick Gaseous Electron Multiplier (THGEM). The detector consists of a thin Boron layer, for neutron-to-charged particle conversion, coupled to two THGEM electrodes in cascade for charge amplification and a position-sensitive charge-readout anode. The detector operates in Ne∕(5%)CF4, at atmospheric pressure, in a stable condition at a gain of around 10(4). Due to the geometrical structure of the detector elements (THGEM geometry and charge read-out anode), the image of detector active area shows a large inhomogeneity, corrected using a dedicated flat-filed correction algorithm. The prototype provides a detection efficiency of 5% and an effective spatial resolution of the order of 1.3 mm.

In this work we report and discuss the characterization of the secondary scintillation light emitted by low-pressure tetrafluoromethane (CF4) during avalanche gas processes. The experimental setup consists of a Parallel Plate Avalanche Counter (PPAC) irradiated by 5.5 MeV alpha particles from a collimated 241-Am source. The PPAC is operated in CF4 at pressures ranging from 5 to 50 torr. The electroluminescence light is readout by a VUV-sensitive Multi-Pixel Photon Counter (MPPC, Hamamatsu), placed along the PPAC axial direction. The secondary scintillation yield at different operational pressures was computed from the correlation between avalanche charge and electroluminesce light, recorded on an event-by-event basis; it was found to be in the range of 0.01–0.15 photons/electron depending on the reduced field applied between the PPAC electrodes. The role of the quencher impurities is also briefly discussed. In addition, the coincidence resolving times (CRT) for 5.5 MeV α -particles crossing the PPAC has been measured; time resolutions of 600 picosecond were achieved at different pressures.

Novel high efficiency fast-neutron detectors were suggested for fan-beam tomography applications. They combine multi-layer polymer converters in gas medium, coupled to thick gaseous electron multipliers (THGEM). In this work we discuss the results of a systematic study of the electron transport inside a narrow gap between successive converter foils, which affects the performance of the detector, both in terms of detection efficiency and localization properties. The efficiency of transporting ionization electrons was measured along a 0.6 mm wide gas gap in 6 and 10 mm wide polymer converters Computer simulations provided conceptual understanding of the observations. For a drift lengths of 6 mm electrons were efficiently transported along the narrow gas gap, with minimal diffusion-induced losses; an average collection efficiency of 95% was achieved for the ionization electrons induced by a primary electron of a few keV initial energy. The 10 mm height converter yielded considerably lower efficiency due to electrical and mechanical flaws of the converter foils. The results indicate that detection efficiencies of around 7% can be expected for 2.5 MeV neutrons with 300 foils converters, of 6 mm height, 0.4 mm thick foils and 0.6 mm gas gap., 19 pages, 18 figures, Journal of Instrumentation (JINST)

The conceptual design and operational principle of a novel high-efficiency, fast neutron imaging detector based on THGEM, intended for future fan-beam transmission tomography applications, is described. We report on a feasibility study based on theoretical modeling and computer simulations of a possible detector configuration prototype. In particular we discuss results regarding the optimization of detector geometry, estimation of its general performance, and expected imaging quality: it has been estimated that detection efficiency of around 5-8% can be achieved for 2.5MeV neutrons; spatial resolution is around one millimeter with no substantial degradation due to scattering effects. The foreseen applications of the imaging system are neutron tomography in non-destructive testing for the nuclear energy industry, including examination of spent nuclear fuel bundles, detection of explosives or drugs, as well as investigation of thermal hydraulics phenomena (e.g., two-phase flow, heat transfer, phase change, coolant dynamics, and liquid metal flow)., Comment: 11 Pages; 6 Figures; Proceeding of the International Workshop on Fast Neutron Detectors and Application FNDA2011, Ein Gedi, Israel, November 2011. Published on the Journal of Instrumentation; 2012 JINST 7 C02056

OBJECTIVE: The aim of this study was to assess the effect of Kinesio Taping on body stability in subjects with MS. STUDY DESIGN: Non controlled intervention study in a Rehabilitation Unit. INTERVENTION: A consecutive convenience sample of 15 individuals with multiple sclerosis was assessed. Kinesio Tex Tape was applied directly to the skin of both calves and kept for the next two days. MAIN OUTCOME MEASURES: Clinical and stabilometric assessments were performed at baseline, immediately after application of the tape and the day after its removal. To control for learning effect 10 subject with multiple sclerosis were tested repeatedly under the same conditions without tape. RESULTS: No statistically or clinically relevant differences were observed among conditions in the mediolateral plane. In the AP plane Friedman's ANOVA showed statistically significant differences between baseline and taping condition with respect to length of sway. A trend towards statistically relevant differences were found also with respect to mean sway and velocity of sway. No learning effect was found for repeated testing within the no treated group. CONCLUSIONS: These preliminary results suggest that the use of ankle taping may be useful in immediately stabilising body posture.

Gaseous PhotoMultipliers (GPM) are a very promising alternative of vacuum PMTs especially for large-size noble-liquid detectors in the field of Functional Nuclear Medical Imaging and Direct Dark Matter Detection. We present recent characterization results of a Hybrid-GPM made of three Micropattern Gaseous Structures; a Thick Gaseous Electron Multiplier (THGEM), a Parallel Ionization Multiplier (PIM) and a MICROMesh GAseous Structure (MICROMEGAS),operating in Ne/CF4 (90:10). Gain values close to 10^7 were recorded in this mixture, with 5.9keV x-rays at 1100 mbar, both at room temperature and at that of liquid xenon (T = 171K). The results are discussed in term of scintillation detection. While the present multiplier was investigated without photocathode, complementary results of photoextraction from CsI UV photocathodes are presented in Ne/CH4 (95:5) and CH4 in cryogenic conditions., Comment: 7 pages, 6 figures, Proceeding of the NDIP Conference 2011 to be published in NIM A

We report on the results of an extensive R&D program aimed at the evaluation of Thick-Gas Electron Multipliers (THGEM) as potential active elements for Digital Hadron Calorimetry (DHCAL). Results are presented on efficiency, pad multiplicity and discharge probability of a 10x10 cm2 prototype detector with 1 cm2 readout pads. The detector is comprised of single- or double-THGEM multipliers coupled to the pad electrode either directly or via a resistive anode. Investigations employing standard discrete electronics and the KPiX readout system have been carried out both under laboratory conditions and with muons and pions at the CERN RD51 test beam. For detectors having a charge-induction gap, it has been shown that even a ~6 mm thick single-THGEM detector reached detection efficiencies above 95%, with pad-hit multiplicity of 1.1-1.2 per event; discharge probabilities were of the order of 1e-6 - 1e-5 sparks/trigger, depending on the detector structure and gain. Preliminary beam tests with a WELL hole-structure, closed by a resistive anode, yielded discharge probabilities of, 15 pages, 11 figures, MPGD2011 conference proceeding

The properties of UV-photon imaging detectors consisting of CsI-coated THGEM electron multipliers are summarized. New results related to detection of Cherenkov light (RICH) and scintillation photons in noble liquid are presented., Comment: 5 Pages, 10 Figures; Presented at the 7th International Workshop on Ring Imaging Cherenkov Detectors (RICH 2010) RICH2010 - Cassis, Provence, France, 3-7 May 2010

This article presents a detector system consisting of three components, a CMOS imaging array, a gaseous-detector structure with a Micromegas layout and a UV-photon sensitive CsI reflective photocathode. All three elements have been monolithically integrated using simple post-processing steps. The Micromegas structure and the CMOS imaging chip are not impacted by the CsI deposition. The detector operated reliably in He/isobutane mixtures and attained charge gains with single photons up to a level of 6 \cdot 10^4. The Timepix CMOS array permitted high resolution imaging of single UV-photons. The system has an MTF50 of 0.4 lp/pixel which corresponds to app. 7 lp/mm., Comment: 4 pages with 8 figures. Submitted to Nucl. Instr. and Meth. A (Elsevier) for proceedings of VCI 2010.

The operation of single-, double- and triple-THGEM UV-detectors with reflective CsI photocathodes (CsI-THGEM) in Ne/CH4 and Ne/CF4 mixtures was investigated in view of their potential applications in RICH. The studies were carried out with UV, x-rays and ��-electrons and focused on the maximum achievable gain, discharge probability, cathode excitation effects and long-term gain stability. Comparative studies under similar conditions were made in CH4, CF4 and Ne/CF4, with a MWPC coupled to a reflective CsI photocathode (CsI-MWPC). It was found that at counting rates 10 Hz/mm^2 it dropped with rate. In all cases investigated the attainable CsI-THGEM gain was significantly higher than that of the CsI-MWPC, under similar conditions. Furthermore, the CsI-THGEM UV-detector suffered fewer cathode-excitation induced effects as compared to CsI-MWPC and had better stability at high counting rates., 25 pages, 25 figures, paper submitted to JINST

The article deals with the detection efficiency of UV-photon detectors consisting of Thick Gas Electron Multipliers (THGEM) coated with CsI photocathode, operated in atmospheric Ne/CH4 and Ne/CF4 mixtures. We report on the photoelectron extraction efficiency from the photocathode into these gas mixtures, and on the photoelectron collection efficiency into the THGEM holes. Full collection efficiency was reached in all gases investigated, in some cases at relatively low multiplication. High total detector gains for UV photons, in excess of 10^5, were reached at relatively low operation voltages with a single THGEM element. We discuss the photon detection efficiency in the context of possible application to RICH., 13 pages, 9 figures, 1 table. Presented at MPGD09, Crete, June 2009; to be published in JINST-proceedings

The operation of Thick Gaseous Electron Multipliers (THGEM) in Ne and Ne/CH4 mixtures, features high multiplication factors at relatively low operation potentials, in both single- and double-THGEM configurations. We present some systematic data measured with UV-photons and soft x-rays, in various Ne mixtures. It includes gain dependence on hole diameter and gas purity, photoelectron extraction efficiency from CsI photocathodes into the gas, long-term gain stability and pulse rise-time. Position resolution of a 100x100 mm^2 X-rays imaging detector is presented. Possible applications are discussed., Submitted to JINST, 25 pages, 33 figures

We briefly review the concept and properties of the Thick GEM (THGEM); it is a robust, high-gain gaseous electron multiplier, manufactured economically by standard printed-circuit drilling and etching technology. Its operation and structure resemble that of GEMs but with 5 to 20-fold expanded dimensions. The millimeter-scale hole-size results in good electron transport and in large avalanche-multiplication factors, e.g. reaching 10^7 in double-THGEM cascaded single-photoelectron detectors. The multiplier's material, parameters and shape can be application-tailored; it can operate practically in any counting gas, including noble gases, over a pressure range spanning from 1 mbar to several bars; its operation at cryogenic (LAr) conditions was recently demonstrated. The high gain, sub-millimeter spatial resolution, high counting-rate capability, good timing properties and the possibility of industrial production capability of large-area robust detectors, pave ways towards a broad spectrum of potential applications; some are discussed here in brief., Comment: 8 pages, 11 figures; Invited Review at INSTR08, Novosibirsk, Feb 28-March 5 2008

The time resolution of a double-stage Thick-GEM (THGEM) detector was measured with UV-photons and relativistic electrons. The photon detector, with semitransparent- or reflective-photocathode yielded time resolution of about 8-10ns RMS for single photoelectrons and 0.5-1ns RMS for few-hundred photoelectrons per photon-pulse. Time resolution of about 10ns RMS was recorded for relativistic electrons from a 106Ru source., 8 Pages, 10 Figures, Submitted to JINST

Background The correlation between Zinc concentration in the prostate's peripheral zone to the onset or presence of malignant process needs to be evaluated in detail. Methods Zinc concentration was measured in ∼1–4 mm3 segments of fresh needle-biopsy cores, with X-ray fluorescence, and correlated with the histological findings of these tissue segments. Results Local Zinc concentration is correlated with the presence of cancer (PCa); the higher the Gleason score the greater the Local Zinc depletion. The Zinc value averaged over the entire extracted tissue is specific only to Gleason score 8–9 PCa. The results refer to patients avoiding Zinc-rich supplements since those show elevated prostatic Zinc concentration in identified cancer tissue. A computer simulation analysis of randomly located 0.03–3.3 cm3 lesions, with particular Gleason score and the measured Local Zinc concentration, revealed a potential diagnostic approach definitely superior to PSA, with sensitivity to the tumor grade and with excellent detection capability for Gleason score >6. Further clinical studies have been designed, both on full prostates after radical prostatectomy as well as on biopsy cores at higher resolution, to establish the accuracy of the method for Gleason score = 6. Conclusions The PCa diagnostic potential of Local Zinc concentration is confirmed and there is indication that the amount of Zinc depletion could be used as a measure of the Gleason score of the tumor. Local Zinc concentration mapping has the potential to improve patient selection for biopsy, biopsy site selection and local therapy (e.g., Cryotherapy, Brachytherapy) site selection. Prostate 68:994–1006, 2008. © 2008 Wiley-Liss, Inc.

We present the results of our recent studies on a Thick Gas Electron Multiplier (THGEM)-based imaging detector prototype. It consists of two 100x100 mm^2 THGEM electrodes in cascade, coupled to a resistive anode. The event location is recorded with a 2D double-sided readout electrode equipped with discrete delay-lines and dedicated electronics. The THGEM electrodes, produced by standard printed-circuit board and mechanical drilling techniques, a 0.4 mm thick with 0.5 mm diameter holes spaced by 1 mm. Localization resolutions of about 0.7 mm (FWHM) were measured with soft x-rays, in a detector operated with atmospheric-pressure Ar/CH4; good linearity and homogeneity were achieved. We describe the imaging-detector layout, the resistive-anode 2D readout system and the imaging properties. The THGEM has numerous potential applications that require large-area imaging detectors, with high-rate capability, single-electron sensitivity and moderate (sub-mm) localization resolution., Published in JINST, 22 pages, 18 figures

We present the results of our recent studies of a Thick Gaseous Electron Multiplier (THGEM)-based detector, operated in Ar, Xe and Ar:Xe (95:5) at various gas pressures. Avalanche-multiplication properties and energy resolution were investigated with soft x-rays for different detector configurations and parameters. Gains above 10E4 were reached in a double-THGEM detector, at atmospheric pressure, in all gases, in almost all the tested conditions; in Ar:Xe (95:5) similar gains were reached at pressures up to 2 bar. The energy resolution dependence on the gas, pressure, hole geometry and electric fields was studied in detail, yielding in some configurations values below 20% FWHM with 5.9 keV x-rays., Comment: 19 pages, 17 figures, published in JINST

The thick GEM (THGEM) [1] is an "expanded" GEM, economically produced in the PCB industry by simple drilling and etching in G-10 or other insulating materials (fig. 1). Similar to GEM, its operation is based on electron gas avalanche multiplication in sub-mm holes, resulting in very high gain and fast signals. Due to its large hole size, the THGEM is particularly efficient in transporting the electrons into and from the holes, leading to efficient single-electron detection and effective cascaded operation. The THGEM provides true pixilated radiation localization, ns signals, high gain and high rate capability. For a comprehensive summary of the THGEM properties, the reader is referred to [2, 3]. In this article we present a summary of our recent study on THGEM-based imaging, carried out with a 10x10 cm^2 double-THGEM detector., Comment: 3 pages, 3 figures. Presented at the 10th Pisa Meeting on Advanced Detectors; ELBA-Italy; May 21-27 2006

In view of a possible application as a charge-particle track readout for an Active Target Time Projection Chamber (AT-TPC), the operating properties of THick Gaseous Electron Multipliers (THGEM) in pure low-pressure Helium were investigated. This paper includes the effective gain dependence on pressure for different detector configurations (single-, double-, triple-cascade setup), long-term gain stability and energy resolution from tracks of 5.5 MeV alpha particles. Stable operational conditions and maximum detector gains of 10^4-10^7 have been achieved in pure Helium at pressure ranging from 100 torr up to 760 torr. Energy resolution of 6.65% (FWHM) for 690 keV of energy deposited by 5.5 MeV alpha particles at 350 torr was measured. The expected energy resolution for the full track is around 2.4% (FWHM). These results, together with the robustness of THGEM electrodes against spark damage, make THGEM structures highly competitive compared to other technologies considered for TPC applications in an active target operating with pure noble gases, requiring a high dynamic range and a wide operating pressure range down to few hundred torr., Comment: Submitted to the Journal of Instrumentation (JINST). 15 pages, 14 figures

We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.