In this work, we present experimental results of a prompt gamma camera for real-time proton beam range verification. The detection system features a pixelated Cerium doped lutetium based ...scintillation crystal, coupled to Silicon PhotoMultiplier arrays, read out by dedicated electronics. The prompt gamma camera uses a knife-edge slit collimator to produce a 1D projection of the beam path in the target on the scintillation detector. We designed the detector to provide high counting statistics and high photo-detection efficiency for prompt gamma rays of several MeV. The slit design favours the counting statistics and could be advantageous in terms of simplicity, reduced cost and limited footprint. We present the description of the realized gamma camera, as well as the results of the characterization of the camera itself in terms of imaging performance. We also present the results of experiments in which a polymethyl methacrylate phantom was irradiated with proton pencil beams in a proton therapy center. A tungsten slit collimator was used and prompt gamma rays were acquired in the 3-6 MeV energy range. The acquisitions were performed with the beam operated at 100 MeV, 160 MeV and 230 MeV, with beam currents at the nozzle exit of several nA. Measured prompt gamma profiles are consistent with the simulations and we reached a precision (2σ) in shift retrieval of 4 mm with 0.5 × 10(8), 1.4 × 10(8) and 3.4 × 10(8) protons at 100, 160 and 230 MeV, respectively. We conclude that the acquisition of prompt gamma profiles for in vivo range verification of proton beam with the developed gamma camera and a slit collimator is feasible in clinical conditions. The compact design of the camera allows its integration in a proton therapy treatment room and further studies will be undertaken to validate the use of this detection system during treatment of real patients.
We study the distribution of maximal-chain lengths between two elements of a causal set and its relationship with the embeddability of the causal set in a region of flat spacetime. We start with ...causal sets obtained from uniformly distributed points in Minkowski space. After some general considerations we focus on the 2-dimensional case and derive a recursion relation for the expected number of maximal chains
n
k
as a function of their length
k
and the total number of points
N
between the maximal and minimal elements. By studying these theoretical distributions as well as ones generated from simulated sprinklings in Minkowski space we identify two features, the most probable path length or peak of the distribution
k
0
and its width
Δ
, which can be used both to provide a measure of the embeddability of the causal set as a uniform distribution of points in Minkowski space and to determine its dimensionality, if the causal set is manifoldlike in that sense. We end with a few simple examples of
n
k
distributions for non-manifoldlike causal sets.
The K¯N system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the K-series X-rays of kaonic hydrogen ...atoms at the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati, and have determined the most precise values of the strong-interaction energy-level shift and width of the 1s atomic state. As X-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be ϵ1s=−283±36(stat)±6(syst) eV and Γ1s=541±89(stat)±22(syst) eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy K¯N interaction.
One of the major limitations of X-ray Absorption Spectroscopy (XAS) experiment at synchrotron facilities is the performance of the detectors. In order to be able to measure more challenging samples ...and to cope with the very high photon flux of the current and future (diffraction limited) sources, technological developments of detectors are necessary. This article reports on the construction and characterization of a monolithic 19-channel germanium detector demonstrator fitted with CMOS preamplifiers. The detector was characterized in the laboratory with radioactive sources and with the X-ray synchrotron beam. Characteristics such as energy resolution, linearity, counting rate capabilities, and stability of the detector were thoroughly evaluated. In addition, it was proved that by using an advanced pulse processor such as Xspress4, it was possible to improve the performance of the detector system by eliminating the crosstalk among channels and by suppressing the charge-shared events. This work could pave the way to enhanced germanium fluorescence detectors for high-throughput X-ray spectroscopy.
In this work we present the results of the experimental characterization of Silicon Drift Detectors (SDDs) readout by CUBE preamplifiers for X-ray spectroscopy measurements. One specific goal of the ...work was to characterize SDDs of different sizes cooled at low temperature in view of their use in the upgrade of the SIDDHARTA nuclear physics experiment. Beside the target application, the results of this work are also of interest for a more extended use of the SDDs in other X-ray spectroscopy applications. The SDDs have been designed as single units with square shape of different areas, 64 mm 2 (8 mm × 8 mm) and 144 mm 2 (12 mm × 12 mm), and also as monolithic array of 3×3 elements of the 8 mm × 8 mm unit (total area 26 mm × 26 mm). The read-out of the SDDs is based on a CMOS (Complementary Metal Oxide Semiconductor) preamplifier (CUBE) both for the single unit and for the 3×3 array. For the readout of the array, an Application Specific Integrated Circuit (ASIC) has been used. An energy resolution better than 124 eV at the Mn-Kα line has been measured with a 64 mm 2 SDD cooled at the temperature of 50 K. The energy resolution remains good (<;130 eV) also at short shaping time (250 ns) thanks to the noise feature of the CUBE preamplifier. Results of measurements on SDDs of different format and also on arrays of SDDs are presented in this work.
The detection module of the ARDESIA spectrometer, an SDD-based, multichannel X-ray detector is presented. The detector design and experimental characterization are discussed. ARDESIA has been ...optimized for synchrotron radiation applications that require high-rate (>1-Mcps per channel) and high-resolution (better than 200 eV at 6 keV) X-ray detection. The main target applications considered in this development are X-ray fluorescence and X-ray absorption fine structure spectroscopy, in particular for the DAFNE-Light DXR1 beamline at LNF (Frascati, Italy). This detector is based on a compact unit (16 mm <inline-formula> <tex-math notation="LaTeX">\times16 </tex-math></inline-formula> mm) that can be replicated and juxtaposed with several units, thus easily covering different detection configurations. The detector consists of a four-channel monolithic array of SDDs, produced by Fondazione Bruno Kessler (Trento, Italy) connected to a four-channel monolithic CUBE preamplifier mounted on the same carrier. The CUBE preamplifier, compatible with both analog and digital pulse processing, enables reaching high count rates (1-Mcps per channel), while keeping good spectroscopic performances. It is extremely low white series noise guarantees good energy resolution, even at short pulse processing times (below 200 ns).
The first observation of the kaonic 3He 3d→2p transition was made, using slow K− mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors ...using the timing information of the K+K− pairs of ϕ-meson decays produced by the DAΦNE e+e− collider. The strong interaction shift of the kaonic 3He 2p state was determined to be −2±2(stat)±4(syst) eV.
Agrivoltaics describes concurrent agricultural production of crops and photovoltaic generation of electricity on the same cropland. By using tinted semi‐transparent solar panels, this study ...introduces a novel element to transform the concept of agrivoltaics from just solar‐sharing to selective utilization of different light wavelengths. Agrivoltaic growth of basil and spinach is tested. When compared with classical agriculture, and based on the feed‐in‐tariff of the experimental location, agrivoltaic co‐generation of biomass and electricity is calculated to result in an estimated financial gross gain up to +2.5% for basil and +35% for spinach. Marketable biomass yields do not change significantly for basil, while a statistically significant loss is observed for spinach. This is accompanied by a relative increase in the protein content for both plants grown under agrivoltaic conditions. Agrivoltaics implemented with tinted solar panels improve the biomass production per unit amount of solar radiation up to 68%, with up to 63% increase in the ratio of leaf and stem biomass to root. Agrivoltaics can enrich the portfolio of farmers, mitigate risks associated with climate, and vastly enhance global photovoltaics capacity without compromising agricultural production.
Agrivoltaics describes concurrent agricultural production of crops and photovoltaic generation of electricity on the same cropland. Here the combination of tinted semi‐transparent photovoltaic panels with growth of two crops of major commercial significance, basil and spinach are studied. This work develops the concept of agrivoltaics from just solar‐sharing to selective utilization of different light wavelengths.
PDF
