Neutrinos are abundantly produced in the LHC. Flavour composition and energy reach of the neutrino flux from proton-proton collisions depend on the pseudorapidity . At large , energies can exceed the ...TeV, with a sizeable contribution of the τ flavour. A dedicated detector could intercept this intense neutrino flux in the forward direction, and measure the interaction cross section on nucleons in the unexplored energy range from a few hundred GeV to a few TeV. The high energies of neutrinos result in a larger N interaction cross section, and the detector size can be relatively small. Machine backgrounds vary rapidly while moving along and away from the beam line. Four locations were considered as hosts for a neutrino detector: the CMS quadrupole region (25 m from CMS Interaction Point (IP)), UJ53 and UJ57 (90 and 120 m from CMS IP), RR53 and RR57 (240 m from CMS IP), TI18 (480 m from ATLAS IP). The potential sites are studied on the basis of (a) expectations for neutrino interaction rates, flavour composition and energy spectrum, (b) predicted backgrounds and in situ measurements, performed with a nuclear emulsion detector and radiation monitors. TI18 emerges as the most favourable location. Already with 150 fb−1 expected in LHC Run3, a small detector in TI18 could measure, for the first time and with good precision, the high-energy N cross section for all neutrino flavours.
The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide ...therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.
We discuss an experiment to investigate neutrino physics at the LHC, with emphasis on tau flavour. As described in our previous paper Beni et al (2019 J. Phys. G: Nucl. Part. Phys. 46 115008), the ...detector can be installed in the decommissioned TI18 tunnel, ≈480 m downstream the ATLAS cavern, after the first bending dipoles of the LHC arc. The detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudorapidity η, where neutrino energies can exceed a TeV. This paper focuses on exploring the neutrino pseudorapity versus energy phase space available in TI18 in order to optimize the detector location and acceptance for neutrinos originating at the pp interaction point, in contrast to neutrinos from pion and kaon decays. The studies are based on the comparison of simulated pp collisions at s= 13 TeV: PYTHIA events of heavy quark (c and b) production, compared to DPMJET minimum bias events (including charm) with produced particles traced through realistic LHC optics with FLUKA. Our studies favour a configuration where the detector is positioned off the beam axis, slightly above the ideal prolongation of the LHC beam from the straight section, covering 7.4 < η < 9.2. In this configuration, the flux at high energies (0.5-1.5 TeV and beyond) is found to be dominated by neutrinos originating directly from IP1, mostly from charm decays, of which ≈50% are electron neutrinos and ≈5% are tau neutrinos. The contribution of pion and kaon decays to the muon neutrino flux is found small at those high energies. With 150 fb−1 of delivered LHC luminosity in Run 3 the experiment can record a few thousand very high energy neutrino charged current (CC) interactions and over 50 tau neutrino CC events. These events provide useful information in view of a high statistics experiment at HL-LHC. The electron and muon neutrino samples can extend the knowledge of the charm PDF to a new region of x, which is dominated by theory uncertainties. The tau neutrino sample can provide first experience on reconstruction of tau neutrino events in a very boosted regime.
In Cone-Beam Computed Tomography (CBCT) the X-ray scatter control and reduction is one of the major challenges because CBCT is less immune to scatter than fan-beam CT. In breast volume imaging, ...studies on Cone-Beam Breast Computed Tomography (CBBCT) have shown the necessity to implement an efficient scatter reduction technique for a successful implementation of a breast CT scan using cone-beam geometry. X-ray scatter reduces image contrast, increases image noise and introduces reconstruction artifacts. A method for scatter evaluation through Monte Carlo simulations is investigated, leading to a scatter correction procedure applied to measured projections via subtraction of the simulated scatter component. Simulations are compared with measurements performed with a CBBCT prototype scanner. This paper presents the evaluation of the method through phantom studies on a cylindrical and on a hemi-ellipsoidal PMMA test object of 120- or 140-mm diameter at its base, simulating the pendant breast. The results indicate that this correction method is effective to reduce and correct X-ray scatter, with no increase of noise in the CT images. The cupping artifact due to scatter was reduced by a factor 3 (from 23% to 7%) for the hemi-ellipsoidal phantom of 140-mm diameter. Correspondingly, the relative noise in the CT slices remains constant to about 3%; the figure of merit for evaluating the correction efficacy was 98% of the ideal case. We discuss the application of this procedure to model breasts characterized in terms of few parameters, as indicated by recent published results of breast anatomy characterization derived from CBBCT patient data, from which a possible parametric breast size model in terms of bra cup size can be set forth. The scatter correction could be applied to projections from patient scans obtained with a breast holder, on the basis of a pre-determined database of simulated scatter distributions corresponding to the breast holder size, shape and estimated volume glandular fraction, for given beam quality and scanner geometry.
Fission at intermediate neutron energies Meo, S Lo; Mancusi, D; Massimi, C ...
Journal of physics. Conference series,
01/2014, Letnik:
533, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In the present work, as a theoretical support to the campaign of neutron cross section measurements at the n_TOF facility at CERN1, Monte Carlo calculations of fission induced by neutrons in the ...energy range from 100 MeV to 1 GeV are carried out by means of a recent version of the Liege Intranuclear Cascade Model, INCL++6, coupled with different evaporation-fission codes, such as Gemini++7 and ABLA078. Theoretical cross sections are compared with experimental data obtained by the n_TOF collaboration and perspectives for future theoretical work are outlined.
The (n,f) cross-sections proposed as references by the IAEA for 235U, 238U and 209Bi are compared with a new analysis that combines the measurements performed at CERN-n_TOF of their cross-section ...ratios with new calculations done using Monte Carlo codes based on phenomenological models INCL+ +, GEMINI+ +, and ABLA07. The calculations are cross-checked with those for the (p,f) reactions, where experimental values are available. We have evaluated in this way the (n,f) cross sections for 238U, 235U and 209Bi, in the intermediate energy region going from 190 MeV to 2 GeV. Our results definitively discard the JENDL/HE-2007 evaluations above 300 MeV, falling inside the confidence corridor proposed by IAEA but for the points around 300–400 MeV where a discrepancy is to be noticed.
Fission at intermediate nucleon energies Meo, S Lo; Mancusi, D; Massimi, C ...
Journal of physics. Conference series,
01/2014, Letnik:
527, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In the present work Monte Carlo calculations of fission of actinides and pre- actinides induced by protons and neutrons in the energy range from 100 MeV to 1 GeV are carried out by means of a recent ...version of the Liège Intranuclear Cascade Model, INCL++, coupled with different evaporation-fission codes, in particular GEMINI++ and ABLA07. Fission model parameters are adjusted on experimental (p, f) cross sections and used to predict (n, f) cross sections, in order to provide a theoretical support to the campaign of neutron cross section measurements at the n_TOF facility at CERN.
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Neutron production and transport in the spallation target of the n_TOF facility at CERN has been simulated with GEANT4. The results obtained with different models of high-energy nucleon-nucleus ...interaction have been compared with the measured characteristics of the neutron beam, in particular the flux and its dependence on neutron energy, measured in the first experimental area. The best agreement at present, within 20% for the absolute value of the flux, and within few percent for the energy dependence in the whole energy range from thermal to 1 GeV, is obtained with the
INCL++
model coupled with the GEANT4 native de-excitation model. All other available models overestimate by a larger factor, of up to 70%, the n_TOF neutron flux. The simulations are also able to accurately reproduce the neutron beam energy resolution function, which is essentially determined by the moderation time inside the target/moderator assembly. The results here reported provide confidence on the use of GEANT4 for simulations of spallation neutron sources.
Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments.
Moreover, ...due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed.
•The design permits to obtain perfectly overlapped images from both devices.•The main peculiarity is to have the same FoV for both detectors.•The overall detector can be also used as portable dual modality device.
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The characteristics of the neutron beam at the new n_TOF-EAR2 facility have been simulated with the Geant4 code with the aim of providing useful data for both the analysis and planning of the ...upcoming measurements. The spatial and energy distributions of the neutrons, the resolution function and the in-beam
-ray background have been studied in detail and their implications in the forthcoming experiments have been discussed. The results confirm that, with this new short (18.5m flight path) beam line, reaching an instantaneous neutron flux beyond 10
5
n/μs/pulse in the keV region, n_TOF is one of the few facilities where challenging measurements can be performed, involving in particular short-lived radioisotopes.
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