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Abstract: The characterization of novel x-ray sources includes the measurement of the photon flux and the energy distribution of the beam produced. The aim of the BEATS2 experiment at INFN-LNF is the study of medical applications of an x-ray source based on Thomson relativistic backscattering. This source is expected to produce pulsed quasi-monochromatic x-ray beam with an instantaneous flux of 1020 ph/s in pulses 10ps long and with an average energy of 20keV. A direct measurement of energy distribution of this beam with traditional detectors, such as HPGe, CZT or CdTe, is very difficult because of the extremely high photon flux. For this reason we have planned to use a technique based on beam filtration using k-edge absorbing foils in the energy range of interest (16–22keV). By measuring the photon flux of the photon beam filtered with appropriate thicknesses of k-edge absorbers, it is possible to retrieve the energy distribution of the incident x-ray beam. The energy resolution obtainable depends on the number and energy separation of k-edges of filter used. A preliminary test of the technique was made using an x-ray tube with a tungsten anode at 22kVp, filtered with 3.1mm of Al providing an x-ray spectrum with an energy distribution similar to that expected from a Thomson source. The comparison between the results obtained directly measuring this spectrum with an HPGe detector and using the k-edge subtraction technique showed good agreement. [Copyright &y& Elsevier]

A prototype of a combined CT–SPECT tomograph for breast cancer study has been developed and evaluated. It allows to perform scintimammography and X-ray CT in the same geometrical conditions. The CT system is based on a quasi-monochromatic beam tuned at 28 keV and an array of ultra fast ceramic scintillators coupled to photodiodes whilst the SPECT system is based on two scintillator matrices coupled to position sensitive photomultipliers. CT and SPECT sinograms of a test phantom were recorded and reconstruted with both modalities. Image fusion of CT and SPECT images was then performed. The developed CT–SPECT prototype is able to detect a region of interest of 1 cm3, with a 10:1 tumour/background concentration ratio, within an object having a diameter of 8 cm. [Copyright &y& Elsevier]

A dedicated small animal PET scanner, YAPPET, was designed and built at Ferrara University. Each detector consists of a 20×20 matrix of 2×2×30 mm3 YAP:Ce finger-like crystals glued together and directly coupled to a Hamamatsu position sensitive photomultiplier. The scanner is made from four detectors positioned on a rotating gantry at a distance of 7.5 cm from the center and the field of view (FOV) is 4 cm both in the transaxial direction and in the axial direction. The system operates in 3D acquisition mode. The performance parameters of YAPPET scanner such as spatial, energy and time resolution, as well as its sensitivity and counting rate have been determined. The average spatial resolution over the whole FOV is 1.8 mm at FWHM and 4.2 mm at FWTM. The sensitivity at the center is 640 cps/μCi. [Copyright &y& Elsevier]

Abstract: The PVLAS experiment aims at the observation and measurement of the effect of magnetic birefringence of vacuum (MBV) predicted by Quantum Electrodynamics. We describe here the new PVLAS apparatus which is currently being set up in INFN Ferrara. The apparatus features two rotating permanent dipole magnets and an ellipsometer operating under UHV with a high finesse Fabry–Perot cavity. [Copyright &y& Elsevier]

The Gamma Beam System of ELI-Nuclear Physics is a high brilliance monochromatic gamma source based on the inverse Compton interaction between an intense high power laser and a bright electron beam with tunable energy. The source, currently being assembled in Magurele (Romania), is designed to provide a beam with tunable average energy ranging from 0.2 to 19.5 MeV, rms energy bandwidth down to 0.5 % and flux of about 1 0 8 photons/s. The system includes a set of detectors for the diagnostic and complete characterization of the gamma beam. To evaluate the spatial distribution of the beam a gamma beam profile imager is required. For this purpose, a detector based on a scintillator target coupled to a CCD camera was designed and a prototype was tested at INFN-Ferrara laboratories. A set of analytical calculations and Monte Carlo simulations were carried out to optimize the imager design and evaluate the performance expected with ELI-NP gamma beam. In this work the design of the imager is described in detail, as well as the simulation tools used and the results obtained. The simulation parameters were tuned and cross-checked with the experimental measurements carried out on the assembled prototype using the beam from an x-ray tube. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the capabilities of a small animal PET scanner, named SiliPET, based on four stacks of double sided silicon strips detectors. Each stack consists of 40 silicon detectors with dimension . These are arranged to form a box with minor sides opened; the box represents the maximal FOV of the scanner. The performance parameters of SiliPET scanner have been estimated, giving an intrinsic spatial resolution of 0.52mm and a sensitivity of 5.1% at the center of the system. [Copyright &y& Elsevier]

ELI-NP-GBS is a high-brilliance gamma source that will produce monochromatic beams in the energy range 0.2–19.5 MeV through inverse Compton scattering. In order to obtain a monochromatic beam a collimation of the emission is necessary. Depending on the energy, the angular aperture required to provide the design bandwidth Δ E/E=0.5% is between 70 and 700 μ rad. This collimation is provided by a stack of 14 tungsten slits, arranged with a relative rotation around the beam axis, so that the overlap will be a continuously adjustable aperture. To monitor the operation and alignment of the collimation, a set of detectors will provide a complete characterization of the gamma beam, including the measurement of the transverse spatial distribution. For this task a gamma beam profile imager based on a thin scintillator screen and a high-resolution CCD-camera was developed. In this work we briefly present the status of the collimation system and beam profile imager, which were designed, assembled and are currently under test at INFN-Ferrara laboratories. [ABSTRACT FROM AUTHOR]

Abstract: We studied with Monte Carlo simulations, using the EGSnrc code, a new scanner for small animal positron emission tomography (PET), based on stacks of double-sided semiconductor detectors. Each stack is composed of planar detectors with dimension 70×60×1mm3 and orthogonal strips on both sides with 500μm pitch to read the two interaction coordinates, the third being the detector number in the stack. Multiple interactions in a stack are discarded. In this way, we achieve a precise determination of the first interaction point of the two 511keV photons. The reduced dimensions of the scanner also improve the solid angle coverage resulting in a high sensitivity. Preliminary results of scanners based on Si planar detectors are presented and the initial tomographic reconstructions demonstrate very good spatial resolution limited only by the positron range. This suggests that, this is a promising new approach for small animal PET imaging. We are testing some double-sided silicon detectors, equipped with 128 orthogonal p and n strips on opposite sides using VATAGP3 ASIC by IDEAS. [Copyright &y& Elsevier]

The ELI-NP facility will provide a monochromatic, high brilliance γ beam with tunable energy up to 19.5 MeV. The time structure of the beam consists of 32 pulses of 1 0 5 photons separated by 16 ns and delivered at repetition rate of 100 Hz. In order to match such unprecedented beam specifications and to measure its energy spectrum, intensity and space profile, a characterization system has been developed. This paper will focus on the working principle, the expected performances and the results of tests carried out on a low-Z sampling calorimeter, made of silicon detectors and polyethylene absorbers, which will measure the average beam energy and its intensity. The results of tests performed with an infrared pulsed laser have shown the capability of the detector to cope with the time structure of ELI-NP beam. Further tests carried out at the LABEC facility in Firenze have shown the excellent linearity of the silicon detectors in the energy range relevant to ELI-NP beam. [ABSTRACT FROM AUTHOR]

The ELI-NP facility, currently being built in Bucharest, Romania, will deliver an intense and almost monochromatic γ beam with tunable energy between 0.2 MeV and 19.5 MeV in two different beamlines. An articulated beam characterization system will be installed downstream of the collimator of each line. The system will use, as calibration candles, a few selected nuclear levels whose fluorescence condition will be monitored by a Nuclear Resonance Scattering System (NRSS). The NRSS will use a peculiar double-readout approach in order to detect resonant events overwhelming background: both scintillation and Cherenkov photons produced inside the same crystals will be separately read. • The NRS system will play a crucial role in the characterization of the Eli-NP beam. • It will be able to give a precise absolute energy calibration of the gamma beam. • The determination of the resonance will be achieved using a matrix of BaF/LYSO crystals. • A novel double readout technique shows a very good background rejection power. [ABSTRACT FROM AUTHOR]

The ELI-NP facility (Extreme Light Infrastructure-Nuclear Physics) will deliver an intense and almost monochromatic gamma beam for frontier research in nuclear physics. Peculiar devices and techniques have been developed to measure and monitor the beam parameters during the commissioning and the operational phase. In this work we will present the Compton Spectrometer, designed to reconstruct the γ beam energy spectrum, by measuring the energy and the position of Compton scattered electrons. The energy and the angle of the scattered electron are measured by a High Purity Germanium detector and a double sided silicon strip detector. The associated photon is detected in coincidence with the electron by barium fluoride (BaF 2) crystals for trigger purpose. In this work we report the status of the characterization carried out on the detectors composing the spectrometer. • Compton spectrometer, designed to reconstruct the ELI-NP γ beam energy spectrum. • Energy of the scattered e − measured with a High Purity Germanium detector. • Scattered angle determined by a double sided silicon strip detector. • Scattered photon detected in coincidence by BaF 2 crystals for trigger purpose. • Tests carried out on the components of the spectrometer are presented. [ABSTRACT FROM AUTHOR]

A Gamma Beam Characterisation System has been designed by the EuroGammaS association for the commissioning and development of the Extreme Light Infrastructure-Nuclear Physics Gamma Beam System (ELI-NP-GBS) to be installed in Magurele, Romania. The characterisation system consists of four elements: a Compton spectrometer, a sampling calorimeter, a nuclear resonant scattering spectrometer (NRSS) and a beam profile imager. In this paper, the nuclear resonant scattering spectrometer system, designed to perform an absolute energy calibration for the gamma beam, will be described. [ABSTRACT FROM AUTHOR]

Abstract: MIRRORCLE is a tabletop synchrotron light source being investigated within an EC funded project named LABSYNC. To evaluate the potential of this novel x-ray source for medical imaging applications, a set of measurements was performed at the MIRRORCLE factory in Japan. In particular, the aim of this work was to characterize the proposed compact x-ray source by determining different parameters, such as the intensity of the broad spectra produced with thin wire targets, the size of the focal spot and its distribution. The average electron-beam impact current on wire targets was calculated by several methods and it was demonstrated to be in the range . By comparing these values with data available for conventional x-ray tubes, the current needed to achieve the same fluence as in a standard diagnostic examination was estimated to be about 0.1–0.5mA. Finally, results from the measurements of the electron-beam impact cross-section on the target suggested that the diameter of the electron beam circulating in the storage ring is about 6mm. [Copyright &y& Elsevier]

Compact gamma cameras based on arrays of compact Position Sensitive Photomultipliers (PSPMTs) (Hamamatsu R7600–C8/12) were recently developed by several research groups. The previous generation of dedicated gamma cameras (5 in. PSPMT) demonstrated the clinical benefit and general diagnostic value for functional breast imaging in comparison with conventional nuclear medicine technique (Anger Camera prone scintimammography and 99mTc Sestamibi administration). The aim of this paper is to investigate how scintillation material and pixel size of crystal arrays can improve image contrast and tumor SNR values. In this paper we compare tumor Signal-to-Noise Ratio (SNR) results obtained by imagers based on CsI(Tl) and NaI(Tl) array, respectively, by means of a liquid and solid breast phantom. The data collected by NaI(Tl) array show a improvement of SNR values for small tumor size (less than 8 mm). The improvement is also evident in small camera, even though for tumor size less than 6 mm the results are near visibility limit. [Copyright &y& Elsevier]

We have been investigating the possibility to readout a large number of crystals (more than 400) by means of WaveLength Shifting (WLS) square section fibers and multi-pixel Hybrid PhotoDiodes (HPDs) for PET applications. However, due to the small light yield, the detection efficiency for 511 keV photons could be too low. To overcome this limitation, we have recently proposed to shape the surface of each finger crystal like an “half-pipe” to achieve a better scintillator—WLS fiber coupling. In this paper, we present the results of the light yield experimental measurements on a test 5×5 “half-pipe” YAP:Ce crystal matrix and a comparison with square fibers—standard matrix configuration.In view of future availability of large-area HPD, we have also assembled a small detector head using a test 4×4 YAP:Ce crystal matrix directly coupled to a 61-pixel HPD. Experimental measurements on the imaging capabilities are also presented. [Copyright &y& Elsevier]