ABSTRACT A new Large-Acceptance Forward Angle Spectrometer [Super Bigbite Spectrometer (SBS)], is under development for the upcoming experiments in Hall A at the Thomas Jefferson National Accelerator Facility (Virginia, USA), where a longitudinally polarized (up to ) electron beam up to 12 GeV energy is now available. The excellent beam intensity (up to 100 A), combined with innovative polarized targets, will provide luminosity up to , opening interesting opportunities to investigate unexplored aspects of the inner structure of the nucleons. In one of the most demanding configuration, the new spectrometer will consist of a dipole magnet, one front charged particle tracker, two identical proton polarimeters with related back trackers and a segmented hadron calorimeter. The front tracker, placed just after the dipole magnet, consists of up to six layers of large area GEM (Gas Electron Multiplier) chambers (); each chamber is made by three adjacent GEM modules of active rectangular area (18 modules as a total). We have chosen the GEM technology in order to optimize spatial resolution (∼80 mm), high hit rate (), cost/performance and high radiation hardness. We present the main features of the SBS front tracker and its GEM detectors and, finally, we discuss the ongoing tracker commissioning at JLab and show some representative test results.

This Article is brought to you for free and open access by the Physics at ODU Digital Commons. It has been accepted for inclusion in Physics Faculty Publications by an authorized administrator of ODU Digital Commons. For more information, please contact digitalcommons@odu.edu. Repository Citation Urciuoli, G. M.; Hayes, D.; Hyde, C. E.; Ibrahim, H. F.; Ulmer, P.E.; and Jefferson Lab Hall A Collaboration, "Spectroscopy of Li-9 (Lambda) by Electroproduction" (2015). Physics Faculty Publications. 152. https://digitalcommons.odu.edu/physics_fac_pubs/152

A dedicated dose delivery monitor is under development for the TOP-IMPLART proton accelerator, the first LINAC for cancer therapy. It is expected to measure the beam intensity profile to precisely monitor the fully active 3+1D (x/y/z and intensity) dose delivery of each short pulse (few μs, 0.1-10 μA pulse current at ∼ 100 Hz) of the therapeutic proton beam (up to 230 MeV). The monitor system consists of planar gas chambers operating in ionization regime with cathode plane made of micro pattern pads alternately connected by orthogonal strips. The dedicated readout electronics features trans-impedance amplifier that dynamically adapts its integrating feedback capacitance to the incoming amount of charge, then opportunistically changing its gain. The measured absolute sensitivity is about 100 fC (better than 0.03 relative sensitivity), the dynamic range up to 10000 (2 gain settings) with time response at the level of few ns, and virtually no dead time. Small scale chamber prototype (0.875 mm pitch pads) and readout electronics have been tested and characterized under both electron (5 MeV) and proton (up to 27 MeV) beams.

Prostate cancer is the most common disease in men and the second leading cause of death from cancer. Generic large imaging instruments used in cancer diagnosis have sensitivity, spatial resolution, and contrast which are inadequate for the task of imaging details of a small organ such as the prostate. In addition, multimodality imaging can play a significant role in merging anatomical and functional details coming from simultaneous PET and MRI. Indeed, multiparametric PET/MRI was demonstrated to improve diagnosis, but it suffers from too many false positives. In order to address the above limits of the current techniques, we have proposed, built and tested, thanks to the TOPEM project funded by Italian National Institute of Nuclear Phisics, a prototype of an endorectal PET-TOF/MRI probe. In the applied magnification PET geometry, performance is dominated by a high-resolution detector placed closer to the source. The expected spatial resolution in the selected geometry is about 1.5mm FWHM and efficiency of a factor 2 with respect to what was obtained with the conventional PET scanner. In our experimental studies, we have obtained a timing resolution of ∼ 320 ps FWHM and at the same time a Depth of Interaction (DOI) resolution of under 1mm. Tests also showed that mutual adverse PET-MR effects are minimal. In addition, the matching endorectal RF coil was designed, built and tested. In the next planned studies, we expect that benefiting from the further progress in scintillator crystal surface treatment, in SiPM technology and associated electronics would allow us to significantly improve TOF resolution.

In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei can provide information on the details of the effective hyperon-nucleon interaction. Electroproduction of the hypernucleus Lambda-9Li has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a 9Be target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. The cross section to low-lying states of Lambda-9Li is concentrated within 3 MeV of the ground state and can be fitted with four peaks. The positions of the doublets agree with theory while a disagreement could exist with respect to the relative strengths of the peaks in the doublets. A Lambda separation energy of 8.36 +- 0.08 (stat.) +- 0.08 (syst.) MeV was measured, in agreement with an earlier experiment.

We developed and tested a new charged particle tracking system, able to operate in high luminosity experiments, which will be installed at Jefferson Laboratory HallA (VA, USA) for optimally exploit the new 12GeV energy electron beam available at the end of 2013. The tracker is made of six GEM (Gas Electron Multiplier) large chambers and two 10×20cm2 planes of SIlicon microstrip Detectors (SIDs). Each GEM chamber is composed by three 40×50cm2 GEM modules, with two-dimensional strip readout, with expected spatial resolution of about 70μm. The same dedicated acquisition system will be used for both detectors (GEM & SID) for a grand total of more than 50,000 channels. The readout electronics is divided into two parts: the front-end cards (based on the existing APV25 chip), hosted on the detectors periphery and the digitizer, a multi purpose VME-64x/VXS board located far from the high radiation environment. The very same electronics has been adopted by the Olympus experiment (DESY, Hamburg, D) to read out the six GEM chambers of its luminosity monitor. The developed detectors and electronics are now ready for the production, which will last for the next 2 years.

The characteristics of the Jefferson Lab electron beam, together with those of the experimental equipment, offer a unique opportunity to study hypernuclear spectroscopy via electromagnetic induced (e,e′K+) reactions. Experiment 94-107 started a systematic study on 1p-shell targets, C12, Be9 and O16. For C12 for the first time measurable strength in the core-excited part of the spectrum between the ground state and the p state was shown in the BΛ12 spectrum. For O16 a high-quality NΛ16 spectrum was produced for the first time with sub-MeV energy resolution. A very precise Λ binding energy value for NΛ16, calibrated against the elementary (e,e′K+) reaction on hydrogen, has also been obtained. Preliminary data on the LiΛ9 spectrum shows some disagreement in strength for the second and third doublet with respect to the theory.

Prostate cancer is the most common disease in men and the second leading cause of cancer death. Generic large instruments for diagnosis have sensitivity, spatial resolution, and contrast inferior with respect to dedicated prostate imagers. Multimodality imaging can play a significant role merging anatomical and functional details coming from simultaneous PET and MRI. The TOPEM project has the goal of designing, building, and testing an endorectal PET-TOF MRI probe. The performance is dominated by the detector close to the source. Results from simulation show spatial resolution of ∼1.5mm for source distances up to 80mm. The efficiency is significantly improved with respect to the external PET. Mini-detectors have been built and tested. We obtained, for the first time, to our best knowledge, timing resolution of <400ps and at the same time Depth Of Interaction (DOI) resolution of 1mm or less.

A unique compact LINAC accelerator for proton therapy is under development in Italy within the TOP-IMPLART project. The proton beam will reach the kinetic energy of 230 MeV, it will have a widely variable current intensity (0.1–10 μA, with average up to 3.5 nA) associated with a high pulse repetition frequency (1–3.5 μs long pulses at 10–100 Hz). The TOP-IMPLART system will provide a fully active 3+1D dose delivery, that is longitudinal (energy modulation), transverse active spot scanning, and current intensity modulation. These accelerator features will permit a highly conformational dose distribution, which therefore requires an effective, online, beam monitor system with wide dynamic range, good sensitivity, adequate spatial resolution and rapid response. In order to fulfill these requisites a new device is under development for the monitoring of the beam intensity profile, its centroid and direction; it is based on transmission, segmented, ionization chambers with typical active area of 100 × 100 mm2. Micro pattern x/y pad like design has been used for the readout plane in order to maximize the field uniformity, reduce the chamber thickness and obtain both beam coordinates on a single chamber. The chamber prototype operates in ionization region to minimize saturation and discharge effects. Simulations (based on FLUKA) have been carried on to study the perturbation of the chamber on the beam parameters and the effects on the delivered dose (on a water phantom). The charge collected in each channel is integrated by dedicated auto-ranging readout electronics: an original scheme has been developed in order to have an input dynamic range greater than 104 with sensitivity better than 3%. This is achieved by a dynamical adjustment of the integrating capacitance to the signal intensity.

A new large-area, lightweight tracker based on the GEM technology is under development for the upcoming experiments in Hall A at Jefferson Lab, where a longitudinally polarized electron beam of 11 GeV will be available in late 2013. This beam, combined with innovative polarized targets, will provide luminosity up to 1039/(s⋅cm2) opening exciting opportunities to investigate unexplored aspects of the inner structure of the nucleon and the dynamics of its constituents. The GEM tracker design is presented in this paper.

A new hybrid silicon μstrip and large area GEM (Gas Electron Multiplier) tracker is under development for the upcoming high luminosity (up to 1039 /s/cm2) experiments at the Hall-A of the JLab 12 GeV electron beam facility. The system consists of 2 small 10×20 cm2 silicon planes placed near the scattering chamber and 18 40×50 cm2 GEM modules that form larger chambers with variable active area depending on the experimental needs. Rather general purpose readout electronics has been designed for both detectors and can be adopted in other equipment. It consists of two active components: front-end cards, directly connected to the detector channels and a multi-purpose digitizer board (MPD). The front-end is based on existing 128 channels APV25-S1 chip developed in the framework of LHC experiments. The MPD handles 16 front-end cards (for a total of 2048 channels) and can be used in VME environments (also VME64x or VXS). It also provides: optical, Ethernet, USB. These resources permit to use MPD cards in different frameworks, ranging from small bench-top to large on-detector distributed systems. The GEM project is part of the CERN/RD51 collaboration activities. The system has been beam tested in late 2010 and 2011, some results are presented here.

A new proton beam monitoring system and its dedicated electronics is under development for the TOP-IMPLART proton therapy facility, based on 10 to 100 Hz pulsed proton LINAC, with maximum kinetic energy of 230 MeV. The system consists of segmented ionization chambers that will measure the beam intensity profile, position and direction to monitor the fully active 3+1D beam. The chamber readout electronics, based on multiplexed multichannel sample and hold, dynamically adapts the integration capacitance on each of its input trans-impedance amplifier to the incoming charge, reaching a rather challenging dynamic range larger than 104 and relative sensitivity better than 3%.

Cardiovascular diseases are the most common cause of death in western countries. Understanding the rupture of vulnerable atherosclerotic plaques and monitoring the effect of innovative therapies of heart failure is of fundamental importance. A flexible, high resolution, high sensitivity detector system for molecular imaging with radionuclides on small animal models has been designed for this aim. A prototype has been built using tungsten pinhole and LaBr3(Ce) scintillator coupled to Hamamatsu Flat Panel PMTs. Compact individual-channel readout has been designed, built and tested. Measurements with phantoms as well as pilot studies on mice have been performed, the results show that the myocardial perfusion in mice can be determined with sufficient precision. The detector will be improved replacing the Hamamatsu Flat Panel with Silicon Photomultipliers (SiPMs) to allow integration of the system with MRI scanners. Application of LaBr3(Ce) scintillator coupled to photosensor with high photon detection efficiency and excellent energy resolution will allow dual-label imaging to monitor simultaneously the cardiac perfusion and the molecular targets under investigation during the heart therapy.

Optimal exploitation of Multi Anode PhotoMultiplier Tubes (MAPMT) as imaging devices requires the acquisition of a large number of independent channels; despite the rather wide demand, on-the-shelf electronics for this purpose does not exist. A compact independent channel readout system for an array of MAPMTs has been developed and tested [1,2]. The system can handle up to 4096 independent channels, covering an area of about 20 x 20 cm(2) with pixel size of 3 x 3 mm(2), using Hamamatsu H-9500 devices. The front-end is based on a 64 channels VLSI custom chip called MAROC, developed by IN2P3 Orsay (France) group, controlled by means of a Field Programmable Gate Array (FPGA) which implements configuration, triggering and data conversion controls. Up to 64 front-end cards can be housed in four backplanes and a central unit collects data from all of them, communicating with a control Personal Computer (PC) using an high speed USB 2.0 connection. A complete system has been built and tested. Eight Flat MAPMTs (256 anodes Hamamatsu H-9500) have been arranged on a boundary of a 3 x 3 matrix for a grand total of 2048 channels. This detector has been used to verify the performances of a focusing aerogel RICH prototype using an electron beam at the Frascati (Rome) INFN National Laboratory Beam Test Facility (BTF) during the last week of January 2009. Data analysis is ongoing: the first results are encouraging, showing that the Cherenkov rings are well identified by this system. (C) 2009 Elsevier B.V. All rights reserved.

In 2014 the CEBAF electron accelerator at Jefferson Lab (JLab) will deliver a longitudinally polarized (up to 85%), high intensity (up to 100 μA) beam with maximum energy of 12 GeV, twice the present value. To exploit the new opportunities that the energy upgrade will offer, a new spectrometer (Super BigBite - SBS) is under development, featuring very forward angle, large acceptance and ability to operate in high luminosity environment. The tracking system of SBS will consist of large area (40×150 cm2 and 50×200 cm2), high spatial resolution (better than 100 μm) chambers based on the GEM technology and 2 small (10×20 cm) Silicon Strip Detector planes. The design of the GEM chambers and its sub-components such as the readout electronics is resented here.

Introduction: We describe an open and flexible detector system for studying cardiovascular diseases on mice, namely the detection of atherosclerotic plaques and stem cell therapy of heart infarction. Tests with a prototype on phantom, perfusion SPECT imaging on mice, with different routes of the radiotracer and detection of atherosclerotic plaques on mice have been performed. Methods: A Geant4 code has been used to design a detector system optimized for studying cardiovascular disease on mice, open and flexible enough to be able to host detectors with different modalities (MRI). In order to perform test measurements on detection of atherosclerotic plaques and on perfusion SPECT imaging of mouse heart two prototype modules of the detector made of CsI (Tl) and NaI (Tl) pixellated scintillators coupled to pinhole collimators and PSPMTs. A readout electronics capable of reading out 4096 channels individually at 10-20 KHz was specifically designed and built. Results: Tests performed on phantom show a spatial resolution of 0.8 mm. It can be improved down to 0.3 mm as tradeoff with needed sensitivity. Measurement on transgenic mice after injection of 99Tc-AnnexinV showed suspicious focal activity indicating possible plaques. Myocardial perfusion SPECT study with two different routes of delivery (tail vein and peritoneum) showed that also injecting the radiotracer trough the peritoneum gives good images making possible the use of this technique to monitor the effects of stem cell therapy of infarction on mice. To fully accomplish the objectives of the study will probably require the integration of other modalities (MRI) with significant modifications of the layout, and of the materials and components.

An experimental study of the (16)O(e,e'K(+))(Lambda)(16)N reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K(+))Lambda, Sigma(0) exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76+/-0.16 MeV was obtained for (Lambda)(16)N with better precision than previous measurements on the mirror hypernucleus (Lambda)(16)O. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p(1/2) and p(3/2) hole states of the (15)N core nucleus.

The design and first test results of new readout electronics for a Multi Anode PhotoMultiplier Tube (MAPMT) array is reported. The system has been developed to perform the readout of arrays of 64 or 256-channels MAPMTs, used in single photon imaging applications, such as Single Photon Emission Computed Tomography (SPECT) for medical studies on stem cells or clinical diagnosis of breast-cancer.