Proton Energy Range Research Articles

Time-reversal invariance violation effect in $dd$ scattering

Abstract 

A formalism has been developed for calculating the signal of violation of
time-reversal invariance, provided that
space-reflection ({\color{blue} parity}) invariance
is conserved during the scattering of tensor-polarized deuterons on vector-polarized
 ones. The formalism is based on the Glauber theory with the full consideration of spin dependence of $NN$ elastic scattering amplitudes and spin structure
of colliding deuterons.
The numerical calculations have been carried out in the range of laboratory proton energies of $T_p=0.1$--$1.2$ GeV using the SAID database
for spin amplitudes and in the energy region of the SPD NICA experiment corresponding
to the invariant mass of the interacting nucleon pairs $\sqrt{s_{NN}}= 2.5$--$25$ GeV, using two phenomenological models of $pN$ elastic scattering.
It is found that only one type of the time-reversal non-invariant
{\color{blue} parity} conserving
 $NN$ interaction gives a non-zero contribution to the signal
 in question, that is important for isolating an unknown constant of this interaction from the corresponding data.

Radiophotoluminescence response of LiF:Mg,Ti pellets irradiated with clinical proton beams in the 70–200 MeV energy range

Lithium fluoride doped with Mg and Ti (LiF:Mg,Ti) has been used for several decades as thermoluminescent dosimeter material, but recently also its radiophotoluminescence has been investigated for applications in dosimetry. In this work, LiF:Mg,Ti pellets (TLD-100) were irradiated in a water phantom at CNAO (Pavia, Italy) with therapeutic proton beams at five energies from 70 to 200 MeV in the dose range from 2 to 20 Gy. After irradiation, their visible radiophotoluminescence spectra were measured in controlled conditions and the spectrally-integrated red emission response of radiation-induced color centers has been investigated. The radiophotoluminescence signal, excited by a 445 nm continuous wave laser, was integrated within a 50 nm-wide band around the emission peak of the F2 color centers, located around 670 nm in LiF. The spectrally-integrated signal of the samples irradiated at the energy of 147.7 MeV exhibited a linear dependence with dose. Moreover, this radiophotoluminescence response appears independent from Linear Energy Transfer in the range from 0.8 to 1.6 keV/μm in all the samples irradiated at the dose of 5 Gy. Such independence was found up to 10.3 keV/μm in samples irradiated within two spread out Bragg peaks made of 36 energy components in the entire investigated proton energy range. The radiophotoluminescence response of the TLD-100 pellets was compared to that of nominally-pure LiF crystals irradiated in the same conditions, which show a similar behavior. The results are encouraging for the exploitation of TLD-100 pellets as passive solid-state radiophotoluminescent dosimeters for proton therapy.

Density functional theory to study stopping power of proton in water, lung, bladder, and intestine

Abstract Stopping power, range, and time of proton in water, lung, bladder, and intestinal human tissues are calculated using density functional theory and Beth’s relativistic equation in range of proton energy (0.01–1,000 MeV). The experimental data extracted from SRIM-2013 program were used to proton to the same human tissues applied in the MATLAB-2021 program, and the mean ionization potential of water and the studied tissues is calculated using Gaussian 09W program. A good agreement has been found between our calculations for stopping power, range, and time of protons in the studied human body tissues and SRIM-2013 program calculations.

Study of accelerator-based epithermal neutron flux depending on Li and Be targets

The Li(p,n) and Be(p,n) reactions are widely used as accelerator-based neutron sources for boron neutron capture therapy (BNCT). Because the energy of the neutrons produced by these reactions is high for BNCT, a moderator is required to reduce the energy to the epithermal energy region. The neutron yields and energy spectra derived from the Li(p,n) and Be(p,n) reactions vary with the incident proton energy; a high proton energy results in a high neutron yield. However, a high proton energy can also increase the neutron energy, and in this case, a high neutron energy requires a thick moderator, which decreases the epithermal neutron flux. Notably, these tradeoffs are not completely clear. Furthermore, the upper limit of the epithermal neutron energy used in different BCNT facilities is not the same. Therefore, epithermal neutron flux estimation with applying an appropriate moderator is necessary for comparing epithernal neutron flux depending on the proton energy, target type, and epithermal neutron range definition.In this study, GEANT4 simulations were performed to determine effective moderator materials and thicknesses. After applying a moderator, we examined the epithermal neutron flux by changing the conditions that can influence the epithermal neutron flux, such as the proton energy, target species (Li and Be), and different definitions of the epithermal neutron region. The results showed that the epithermal neutron flux increases with the increasing proton energy until a certain level for both Li and Be targets. For proton energies above 3 MeV for the Li target and above 7 MeV for the Be target, the epithermal neutron flux decreases or its increase rate gradually decreases. And, when the upper energy limit of the epithermal neutron range is changed from 10 keV to 20 keV or 40 keV, the epithermal neutron flux is more than 109 cm−2 s−1 at a proton energy of 3 MeV for Li target and 8 MeV for Be target.

Target Development towards First Production of High-Molar- Activity 44gSc and 47Sc by Mass Separation at CERN-MEDICIS.

The radionuclides 43Sc, 44g/mSc, and 47Sc can be produced cost-effectively in sufficient yield for medical research and applications by irradiating natTi and natV target materials with protons. Maximizing the production yield of the therapeutic 47Sc in the highest cross section energy range of 24-70 MeV results in the co-production of long-lived, high-γ-ray-energy 46Sc and 48Sc contaminants if one does not use enriched target materials. Mass separation can be used to obtain high molar activity and isotopically pure Sc radionuclides from natural target materials; however, suitable operational conditions to obtain relevant activity released from irradiated natTi and natV have not yet been established at CERN-MEDICIS and ISOLDE. The objective of this work was to develop target units for the production, release, and purification of Sc radionuclides by mass separation as well as to investigate target materials for the mass separation that are compatible with high-yield Sc radionuclide production in the 9-70 MeV proton energy range. In this study, the in-target production yield obtained at MEDICIS with 1.4 GeV protons is compared with the production yield that can be reached with commercially available cyclotrons. The thick-target materials were irradiated at MEDICIS and comprised of metallic natTi, natV metallic foils, and natTiC pellets. The produced radionuclides were subsequently released, ionized, and extracted from various target and ion source units and mass separated. Mono-atomic Sc laser and molecule ionization with forced-electron-beam-induced arc-discharge ion sources were investigated. Sc radionuclide production in thick natTi and natV targets at MEDICIS is equivalent to low- to medium-energy cyclotron-irradiated targets at medically relevant yields, furthermore benefiting from the mass separation possibility. A two-step laser resonance ionization scheme was used to obtain mono-atomic Sc ion beams. Sc radionuclide release from irradiated target units most effectively could be promoted by volatile scandium fluoride formation. Thus, isotopically pure 44g/mSc, 46Sc, and 47Sc were obtained as mono-atomic and molecular ScF 2+ ion beams and collected for the first time at CERN-MEDICIS. Among all the investigated target materials, natTiC is the most suitable target material for Sc mass separation as molecular halide beams, due to high possible operating temperatures and sustained release.

Latest results from the RD42 collaboration on the radiation tolerance of polycrystalline diamond detectors

As nuclear and particle physics facilities move to higher intensities, the detectors used there must be more radiation tolerant. Diamond is in use at many facilities due to its inherent radiation tolerance and ease of use. In this article we present our radiation tolerance measurements of the highest quality polycrystalline Chemical Vapor Deposition (pCVD) diamond material for irradiations from a range of proton energies, pions and neutrons up to a fluence of 2×1016particles/cm2. We have measured the damage constant as a function of energy and particle species and compared it with theoretical models. We also present measurements of the rate dependence of pulse height for non-irradiated and irradiated pCVD diamond pad and pixel detectors, including detectors tested over a range of particle fluxes up to 20 MHz/cm2 with both pad and pixel readout electronics. Our test beam results indicate a 2% upper limit to the pulse height dependence of unirradiated and neutron irradiated pCVD diamond detectors leading to the conclusion that the pulse height in pCVD diamond detectors is, at most, minimally dependent on the particle flux.

Measurement of proton induced absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from 16O(p,p ′γ )16O reaction

In this article, we report the absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from the 16O(p,p ′γ )16O reaction for incident proton energy range of 8-16 MeV. Angular distributions of the three γ-rays have been measured for seven angles at 9 MeV proton energy. A detailed phenomenological optical model potential (OMP) was set up to analyse the cross-section data. The OMP parameters were optimised using elastic, polarization and total reaction data available in the literature for protons and neutrons. Low-lying states of 16O were coupled, the optical potential was deformed using deformation parameters, and several resonances were included in the calculations to account for the nuclear structure effects. The potentials so generated have been used to calculate the differential and total cross sections for both 16O(p,p ′ )16O and 16O(p,p ′γ )16O reactions. Our calculated cross-sections are in fairly good agreement with our measured data for 6.13, 6.92 and 7.12 MeV γ-rays. However, there still exist discrepancies in reproduction of the finer details of the cross sections. The comparisons of the calculations with the data bring forth the rather complex roles of channel couplings, resonances in the p+16O system and target deformation in the variation of the cross sections with projectile energy. The increased contribution of nuclear structure effects in light mass nuclei, leads to an apparent loss of predictive power of the theoretical calculation, as we approach the low-energy region of less than 10 MeV projectile energy.

Empirical forecasting models for peak intensities of energetic storm particles at 1 AU

We have investigated the dependence of the peak intensities of energetic storm particles (ESPs) on various parameters characterising the coronal mass ejections (CMEs) and associated phenomena. The aim of this study is to suggest empirical models for forecasting the peak intensities of ESP events at 1 AU based on solar and interplanetary (IP) space observations.For this study we searched for the associations of front-side full and partial halo CMEs with linear speeds >400 km s−1during the years 1996–2015 with IP shocks at 1 AU and ESP events observed near the time when the shock passes the observer. We found 88 CME-driven IP shocks associated with ESP events at proton energy range 5.0–7.2 MeV (nominal energy 6.0 MeV) and 59 shocks at the energy range 15.1–21.9 MeV (nominal energy 18.2 MeV). At these two energies 71% and 68% of the ESP events were associated with solar energetic particle (SEP) events, 85% and 84% were associated with decametric–hectometric (DH) type II radio bursts while 67% and 66% were associated with both.For each CME - shock pair we calculated the predicted shock transit speed (VTR) by using the method of Belov et al. (2022) and used this as the primary parameter in the investigation. We performed correlation analyses between the logarithm of the peak intensities of the ESP events (log10 [IESPpeak]) and the solar parameters related to the CMEs, solar flares, IP shocks, SEP events, and type II radio bursts. When using a single explanatory variable, we found best correlation coefficients for VTR(0.68 ±0.05 and 0.71 ±0.06), the CME space speed (VCMEspace) (0.59 ± 0.05 and 0.68 ± 0.07), and the logarithm of SEP peak intensity (log10 [ISEPpeak]) (0.55 ± 0.08 and 0.70 ±0.08) at 6.0 and 18.2 MeV, respectively. Weak to moderate correlations were found for the logarithm of the soft X-ray flux (log10 [SXRF]) and the logarithm of the duration of DH type II radio burst (log10 [DTII]).Using linear combinations of two or more variables improved the correlations. The best two-variable combination explaining log10 [IESPpeak] was VTRcombined with log10 [ISEPpeak] and the best three- and four-variable combinations also included these two parameters. We found two methods for forecasting ESP peak intensities, one of which can be used for long lead time and the other for medium lead time forecasting. For long lead time forecasting VTR, VCMEspaceand log10 [SXRF] are used. The correlation coefficients between the calculated and observed log10 [IESPpeak] were 0.71 ±0.05 at 6.0 MeV and 0.74 ±0.06 at 18.2 MeV. This method only depends on the coronagraph and X-ray observations at the Sun. For medium lead time forecasting the four parameters used are VTR, log10 [ISEPpeak], VCMEspace(or log10 [SXRF]), and log10 [DTII]. The correlation coefficients were 0.80 ±0.04 at 6.0 MeV and 0.84 ±0.05 at 18.2 MeV. Coronagraph observations at the Sun and solar energetic particle and DH type II burst measurements in IP space are required for this method. The medium lead time forecasting provides an average warning time of 30 ±16 h.

Оценка и анализ поглощённой дозы в гетероструктуре AlGaN/GaN при воздействии ионизирующих потоков радиационных полей Земли в условиях эксплуатации наноспутника

Research of influence of ionizing radiation in the energy range of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV) on circular sun-synchronous orbit on the radiation resistance of the AlGaN/GaN heterostructure as part of the nanosatellite on-board electronic equipment under operating conditions is carried out using physical and mathematical modeling in the stack model approximation. All calculations are based on data from the energy spectra of protons and electrons in sun-synchronous orbit provided Spenvis information system (European Space Agency). The results of calculation of integral fluxes and absorbed doses in aluminum and heterostructure were obtained. An evaluation and analysis of the radiation resistance of the heterostructure under the influence of low- and high-energy ionizing particles and their ability to function throughout the year was carried out.

Radiation tolerance and self-healing in triple halide perovskite solar cells

The high tolerance and stability of triple halide perovskite solar cells is demonstrated in practical space conditions at high irradiation levels. The solar cells were irradiated for a range of proton energies (75 keV, 300 keV, and 1 MeV) and fluences (up to 4 × 1014 p/cm2). The fluences of the energy proton irradiations were varied to induce the same amount of vacancies in the absorber layer due to non-ionizing nuclear energy loss (predominant at <300 keV) and electron ionization loss (predominant at >300 keV). While proton irradiation of the solar cells initially resulted in degradation of the photovoltaic parameters, self-healing was observed after two months where the performance of the devices was shown to return to their pristine operation levels. Their ability to recover upon radiation exposure supports the practical potential of perovskite solar cells for next-generation space missions.

Excitation functions of the 197Au(p,pxn) and 197Au(p,xn) reactions

Abstract The cross-sections for the 197Au(p,pxn)196-193Au and 197Au(p,xn)197,195,193Hg reactions within the proton energy range of 49.8–65.5 MeV were measured at the high-intensity proton linac facility (KOMAC) in Korea using the stacked-foil activation and off-line γ-ray spectrometric technique The proton beam intensity was determined based on the natCu(p,x)62Zn monitor reaction with the recommended cross-section accessed from the IAEA database library. The data gathered in the present work are compared with the available data from the literature, which agreed well with each other. In this study, the 197Au(p,p5n)193Au reaction cross-section was measured for the first time. The data from the present work and existing literature were compared with the TALYS-1.9-based data taken from the TENDL-2019 library, which generally agreed well.

Dose analysis of proton beam therapy in hepatocellular carcinoma using PHITS version 3.20

Hepatocellular Carcinoma (HCC) is one of the deadliest cancers that assault the human liver.. Proton beam therapy (PBT) is a safer therapy for HCC because there is less risk of damaging healthy tissue. The aims of this study were to determine the optimal proton energy for HCC treatment, the effect of proton energy on the rate of absorbed dose for HCC treatment, the effect of proton energy on the total isoeffective dose for the treatment of liver cancer, and safe and effective irradiation techniques for the treatment of HCC. This study is a simulation method using the PHITS 3.20. The PHITS3.20 program begins with defining the geometry, the material for liver cancer, other organs as the object under study, and the energy source used. The proton source used is S2C2 (Superconducting Synchrocyclotron). The independent variable in this study is the proton energy range between 75 MeV to 112 MeV according to the S2C2 output, while the dependent variable is the absorbed dose rate. The results of this study describe the optimum energy for HCC treatment as 88 MeV to 112 MeV; the more significant the energy used, the higher the dose rate for GTV; the more significant the energy used, the higher the dose. The total isoeffective on GTV will be smaller, and a safe and effective irradiation method for treating HCC is the pencil scattering method.

Measurement of the isomeric yield ratios of 196m,gAu and 195m,gHg in the 197Au(p,x) reaction

Abstract In this study, the isomeric yield ratio (IR) values of 196m,gAu and 195m,gHg in the 197Au(p,x) reaction within the proton energy range of 49.8–65.5 MeV were measured at the high-intensity proton linac facility (KOMAC) in Korea using an offline γ-ray spectrometric technique. Furthermore, the IR values of the above-mentioned products at different proton energies were calculated from the cross-sections based on the data in the TENDL-2019 library and are found to be higher than the experimental values. The IR values of 196m,gAu and 195m,gHg in the 197Au(p,x) reaction from the present and other works are compared with the similar literature data in the 197Au(γ,n), 196Hg(γ,n), 197Au(n,2n), 196Hg(n,2n), natPt(α,x) and natPt(3He,x) reactions to examine the role of compound nucleus spin, excitation energy, and input angular momentum.

Differential cross section measurements of the 7Li (p,p΄γ1-0) 7Li reaction suitable for PIGE applications

Differential cross sections of the reaction 7Li(p,p΄γ1-0)7Li were experimentally determined in the proton energy range between 1000 and 4000 keV. The experiment was conducted at the Tandem Accelerator Laboratory of N.C.S.R. “Demokritos”. The detection of the emitted gamma rays, having an energy Eγ = 477.6 keV, was accomplished using four HPGe detectors of relative efficiency varying between 18 and 80%, at the detection angles of 0°, 55°, 90° and 165°. The statistical errors of the measurements did not exceed 4%, while the overall systematic uncertainty budget was also kept as low as possible (∼8%). For the validation of the obtained cross sections a benchmarking experiment was performed using a thick target of known stoichiometry. The comparison with existing experimental datasets in literature is also presented and discussed.

A multi-source based Monte Carlo simulation model for spot scanning proton radiotherapy using GEANT4

Proton therapy is widely used for treating various tumor types due to its favorable dosimetric characteristics compared with conventional radiotherapy. However, a small error in dose calculation may lead to a substantial misadministration of planned radiation dose. This work aims to create a simplified and easy-to-use Monte Carlo (MC) simulation model, based on the multi-source model principle, for spot scanning proton radiotherapy. Our multi-source model contains a set of physical parameters acquired from a Varian ProBeam compact system at the South Florida Proton Therapy Institute (SFPTI). The source model input parameters are mean energy (σΕ) and beam spot (σs) standard deviations, which directly affect the integrated depth-dose (IDD) dosimetric characteristics such as beam width, proton range, and distal fall-off. Despite the simplicity of the presented model, all simulated results matched the corresponding experimental values within 2.5% and were found to be within the acceptable clinical limits, for a wide nominal proton energy range (i.e., 90–220 MeV). Additionally, the comparison of the simulated IDDs with the experimental IDDs was found to be highly conformal with 100% of the points passing the 2%/2 mm gamma index test. The model presented in this work can be efficiently used to model high energy (>80 MeV) in a central axis clinical scanning proton beam in a real clinical setting. The small number of input parameters selected allows for a more efficient and user-friendly MC modeling than previously developed models, while off-axis beam characteristics can be studied with the addition of a new sub-source parameter file.

Investigating the potential contribution of inter-track interactions within ultra-high dose-rate proton therapy

Objective. Laser-accelerated protons offer an alternative delivery mechanism for proton therapy. This technique delivers dose-rates of ≥109 Gy s−1, many orders of magnitude greater than used clinically. Such ultra-high dose-rates reduce delivery time to nanoseconds, equivalent to the lifetime of reactive chemical species within a biological medium. This leads to the possibility of inter-track interactions between successive protons within a pulse, potentially altering the yields of damaging radicals if they are in sufficient spatial proximity. This work investigates the temporal evolution of chemical species for a range of proton energies and doses to quantify the circumstances required for inter-track interactions, and determine any relevance within ultra-high dose-rate proton therapy. Approach. The TOPAS-nBio Monte Carlo toolkit was used to investigate possible inter-track interactions. Firstly, protons between 0.5 and 100 MeV were simulated to record the radial track dimensions throughout the chemical stage from 1 ps to 1 μs. Using the track areas, the geometric probability of track overlap was calculated for various exposures and timescales. A sample of irradiations were then simulated in detail to compare any change in chemical yields for independently and instantaneously delivered tracks, and validate the analytic model. Main results. Track overlap for a clinical 2 Gy dose was negligible for biologically relevant timepoints for all energies. Overlap probability increased with time after irradiation, proton energy and dose, with a minimum 23 Gy dose required before significant track overlap occurred. Simulating chemical interactions confirmed these results with no change in radical yields seen up to 8 Gy for independently and instantaneously delivered tracks. Significance. These observations suggest that the spatial separation between incident protons is too large for physico-chemical inter-track interactions, regardless of the delivery time, indicating such interactions would not play a role in any potential changes in biological response between laser-accelerated and conventional proton therapy.

Cross section measurements of low-energy charged particle induced reactions using moderated neutron counter arrays

A high-and-flat efficiency moderated neutron detection array of 3He counters has been recently developed for photoneutron cross section measurements at the future ELI-NP gamma-ray beam source. We have designed a three rings geometry of 31 counters with a ˜37% efficiency flat within 5% in the 10 keV to 5 MeV neutron energy interval. A commissioning experiment was performed using proton beams delivered by the 9 MV Tandem accelerator of IFIN-HH. We measured the neutron production cross sections for proton induced reactions on nat Cu and 27Al. The (p, xn) reactions on nat Cu were investigated in the 4.5 MeV to 14 MeV proton energy range with 250 keV steps, using pulsed and continuous proton beams. The low energy measurements below 10 MeV served to validate the detection efficiency calibration against well-known natCu(p, n) cross sections. The 27Al(p, n) reaction was investigated in the 5.8 MeV to 6.75 MeV energy range with 5 keV steps. Preliminary cross section results are here compared with preceding data.

Computation of Voxel-by-Voxel Dose Rates in Patients for Proton Pencil Beam Dose Delivery

<h3>Purpose/Objective(s)</h3> Proton beam radiotherapy is most commonly delivered using the pencil beam scanning (PBS) technique. However, the vast majority of clinical outcome data is based on patients treated with the passive scattering technique. The overall dose distributions delivered with these techniques are fairly similar, with an advantage in conformity noted for PBS. Major differences between these two modalities can be observed in the temporal dose delivery pattern. The passive scattering technique uniformly delivers dose across the cross section of the entire target simultaneously, while the dose in PBS is delivered point-by-point, resulting in a much higher local instantaneous dose rate. Recent studies have shown that ultra-high dose rate (FLASH) irradiations can change the biological response to radiation. This work presents an analytical tool to compute voxel-wise maximum dose rates for clinical PBS treatment plans. <h3>Materials/Methods</h3> The scripting environment of our treatment planning system was used to develop software to compute dose rate distributions for clinical pencil beam scanning treatment plans. The basis of the computation is an accurate model of the delivery timing properties of the accelerator and scanning system. The minimum temporal resolution supported is 1 ms. This captures the timing of single spots but excludes the beam pulse structure of our cyclotron (ns). With the timing model and a given spot map we compute the average dose rate over a time interval of interest for each voxel. The latter is an input parameter determined by the user. To validate the tool, test beams in a simple solid water geometry were generated in the treatment planning system and corresponding dose rate distributions produced. Single point measurements with custom-made diode and electronics were used to verify computations against experimentation for a range of proton energies and depths. <h3>Results</h3> For dose rate calculations recording the maximum value observed in any 1 ms time interval during the field's delivery, we observe peak values of 186 Gy/min and 273 Gy/min for 110 MeV and 150 MeV protons, respectively. On average, the agreement of calculations and measurements was -0.9% with a standard deviation of 4.1%. <h3>Conclusion</h3> The software enables accurate local instantaneous dose rate calculations for clinically deliverable treatment plans. This may be important to use as a basis to better understand clinical results. In addition to standard PBS treatments, the observed dose rates may be relevant when considering the out of field areas in FLASH treatments.

Absolute response of a proton detector composed of a microchannel plate assembly and a charge-coupled device to laser-accelerated multi-MeV protons.

The absolute response of a real-time proton detector, composed of a microchannel plate (MCP) assembly, an imaging lens, and a charge-coupled device (CCD) camera, is calibrated for the spectral characterization of laser-accelerated protons, using a Thomson parabola spectrometer (TPS). A slotted CR-39 plate was used as an absolute particle-counting detector in the TPS, simultaneously with the MCP-CCD detector to obtain a calibration factor (count/proton). In order to obtain the calibration factor as a function of proton energy for a wide range of proton numbers, the absolute response was investigated for different operation parameters of the MCP-CCD detector, such as MCP voltage, phosphor voltage, and CCD gain. A theoretical calculation for the net response of the MCP was in good agreement with the calibrated response of the MCP-CCD detector, and allows us to extend the response to higher proton energies. The response varies in two orders of magnitude, showing an exponential increase with the MCP voltage and almost linear increase with the phosphor voltage and the CCD gain. The calibrated detector enabled characterization of a proton energy spectrum in a wide dynamic range of proton numbers. Moreover, two MCP assemblies having different structures of MCP, phosphor screen, and optical output window have been calibrated, and the difference in the absolute response was highlighted. The highly-sensitive detector operated with maximum values of the parameters enables measuring a single proton particle and evaluating an absolute spectrum at high proton energies in a single laser shot. The absolute calibrations can be applied for the spectral measurement of protons using different operating voltages and gains for optimized response in a large range of proton energy and number.

Determination of WER and WET equivalence estimators for proton beams in the therapeutic energy range using MCNP6.1 and TOPAS codes

To use the dosimetric advantages that proton therapy provides, the exact knowledge of the range and its associated parameters of the beam is essential. Since the human body is composed of several tissues whose composition and density differ from water it is important to relate the range in water to the range in those tissues. Those range associated parameters are the Water Equivalent Ratio (WER) and Water Equivalent Thickness (WET). This work presents the Range, WER and WET values obtained from the simulations using the Monte Carlo codes MCNP6.1 and TOPAS for several tissue-equivalent materials, which are materials that reproduce the radiation behavior of the human tissues in a phantom. Simulations have been done in the therapeutic proton energy range from 70 to 225 MeV. Therefore, the main objective of this work is to provide and contribute to the improvement of dose calculation in proton therapy, more specifically in the calculation of WER and WET in tissue equivalent medium. The results showed good agreement between codes, presenting only small differences less than 1.9% in the cortical bone, but they did not affect the dose calculation in the therapeutic range used in this study.