Light Charged Particles Research Articles

Detector Development for a Double-Differential Cross Section Experiment with the Emission of Light Charged Particles from High Energy Neutrons

Detector Development for a Double-Differential Cross Section Experiment with the Emission of Light Charged Particles from High Energy Neutrons

Radiation transmittance of the optical SiO2-based glass system

In this study, parameters related to the transmission resistance of the optical glasses described by 26.47Li2O–(20.59-x)Ta2O5–5.88ZrO2–47.06SiO2–xNb2O5 were evaluated against common ionising radiation such as gamma photons, light and heavy charged particles. A combination of FLUKA simulation code, XCOM, ESTAR, PSTAR, ASTAR, and SRIM were exploited for the evaluation of photon, electron, proton, alpha particle and carbon ion transmission data for particle energies within 15 keV–15 MeV. The increase in Nb2O5 molar concentration generally, deteriorated the photon and charged radiation shielding ability of the glasses. The present glass system showed preferred gamma radiation shielding competence compared to standard glasses and concrete shields.

An SCA ASIC-based multi-channel readout system for a prototype multi-purpose TPC at CSNS Back-n white neutron source

The back-streaming white neutron source (Back-n) at China Spallation Neutron Source (CSNS), which has excellent energy spectrum and good time resolution, provides superior conditions for neutron induced light charged particle tracking experiment. To track light charged particles, CSNS has proposed a project named Multi-purpose Time Projection Chambers (MTPC) and completed a 1519-channel prototype. A multi-channel readout system based on Switched Capacitor Arrays (SCA) waveform sampling ASIC was designed to meet the requirements of the prototype MTPC. This paper presents the structure of this readout system and the results of the beam test with MTPC at CSNS. Time of Flight spectrum of neutron beam and 3D-track of neutron induced light charged particles were successfully reconstructed. These test results prove the feasibility of large-scale MTPC.

Recoil and charged particle energy spectra from the natSi(n,x) reaction and the Si semiconductor detector response to the 14 MeV neutrons

The energy spectra of light and heavy charged particles generated by the 14 MeV neutrons in silicon nuclei and in the Si semiconductor detector (SSD) were analysed. The existing measurements were used to validate the corresponding energy differential cross sections from major evaluations ENDF/B-VIII.0 and JEFF-3.3. The required data were extracted by the various codes: NJOY21, SPKA and MCNP6. It was shown that both evaluations underestimate the high energy part of the 28Si(n,x)p- and α-particle spectra by ≤50%, whereas at smaller emission energies no experimental data even exist. The calculation of the atom displacement damage in SSD reveals that the secondary protons produce additionally ≈15% of damage, whereas the contribution from secondary alphas is impossible to estimate since the Si(α,x) recoil data are not available.The single experiment, carried out by K. Yageta and co-workers in 1988, reported the energy spectra in the Si semiconductor down to the rather low energy of ≈0.3 MeV, at which the production of reaction recoils dominates over the light ions. The Monte Carlo simulation of this experiment was performed by MCNP6. The generation and transport of all relevant ions were taken in account. The energy depositions from protons or alphas were summed with their associated recoils after correction for non-ionization losses. The neutron reactions in the dead layer of the SSD were shown to increase the counts in active layer by (1–20)% depending on sort of ions. The impact of the field funneling effect was studied. Consideration of all these underlying processes has eventually allowed a reasonable reproduction of this experiment.

Characterization of Stray Radiation Produced by a Proton Beam in an Anthropomorphic Phantom with Dental Implants Using a Pixel Detector

<h3>Purpose/Objective(s)</h3> We investigated the scattered radiation produced by a collimated proton beam in the case of head and neck cancer using an anthropomorphic head phantom with human-like anatomy, with two dental implants inserted. Using high-resolution semiconductor pixel detectors, we measured and analyzed the backscatter radiation with particle identification resolving power. This research is focused on giving quantitative information about the radiation field components. <h3>Materials/Methods</h3> A treatment plan was designed on a standard X-ray CT which contained the implants at the center of the tumor. Two irradiations of an anthropomorphic head phantom were performed with clinical proton beams: one without metallic implants (plastic inserts) and one with dental implants. Two titanium cylindrical inserts of 1 cm length and 0.33 cm diameter were placed in the phantom's upper jaw like the molar's replacements. The planning target volume (PTV) is shaped so that the dental inserts are centered in the target volume. A scattered fixed proton beam with a nominal energy of 170 MeV was delivered to the phantom using collimators and boluses designed to shape and stop the beam according to the treatment plan. Scattered primary and secondary radiation was detected with hybrid semiconductor pixel detectors, placed at 4 cm behind the PTV. Detailed description of the mixed-radiation field was performed with spectral (energy loss) and tracking (direction) sensitivity. <h3>Results</h3> Measurements included a low intensity proton beam to assess the particle tracking response and identification resolving power in both situations (with and without implants). In this manner, the components of the radiation field were observed and analyzed. Based on their characteristic directional-sensitive spectral-track signal in the detector, both primary and secondary protons can be distinguished from light charged particles. This was done by analyzing single particle pixelated clusters morphology, spectral and directional sensitive parameters. Directional fluxes and linear energy transfer (LET) spectra of charged particle groups provide information about the scattered radiation field. <h3>Conclusion</h3> We present novel information about dental metallic implants' influences in a proton-based treatment. Preliminary results show differences in the LET distributions of the scattered radiation when the implants are in place, respectively, when they are missing. Further analyses will be done to provide a detailed dissemination of contribution for every type of particle.

Ternary particles of Z =1 to 4 emitted in spontaneous fission of 252Cf

This paper presents the results of ternary light charged particles from 252Cf spontenous fission source. The method DeltaE - E was applied to identify the particle by a position sensitive DeltaE - E telescope.The specific energy loss (DeltaE) was measured using the transmission type DeltaE detector (thicknesses of 150 μm ) ordered from the company Micron Semiconductors, while the residual energy (E) was measured by a Timepix detector with thicknesses of 600 μm . It was possible to measure partial-energy spectra of the various ternary particle types due to the thicknesses of Al foil (31 μm) and DeltaE detector (150 μm) placed before E detector. The energy spectrum of protons was qualitatively different from the spectra of the other particles since protons from Al(n,p) and Si (n,p) reactions could contribute to the spectra.

Experimental study of the Ca40,48+Ca40,48 reactions at 35 MeV/nucleon

In this article we investigate $^{40,48}$Ca+$^{40,48}$Ca peripheral and semi-peripheral reactions at 35 MeV/nucleon. Data were obtained using the unique coupling of the VAMOS high acceptance spectrometer and the INDRA charged particle multidetector.The spectrometer allowed high resolution measurement of charge, mass and velocity of the cold projectile-like fragment (PLF), while the INDRA detector recorded coincident charged particles with nearly $4\pi$ acceptance.The measured isotopic composition of the PLF identified in VAMOS and the average light charged particle (LCP) multiplicities are promising observables to study the isospin diffusion.The detection of the PLF in coincidence with LCP allows the reconstruction of the mass, charge and excitation energy of the associated initial quasi-projectile nuclei (QP), as well as the extraction of apparent temperatures.We investigate the suitability of the isoscaling method with the PLF and the experimental reconstructed QP.The extracted $\alpha$ and $\Delta$ isoscaling parameters present a dependence on the considered system combination that could justify their use as a surrogate for isospin asymmetry in isospin transport studies.The reconstruction of the QP allows to observe an evolution of the $\alpha/\Delta$ with the size of the QP, the latter being consistent with a strong surface contribution to the symmetry energy term in finite nuclei. This leads to the conclusion that the reconstruction of the primary source is mandatory for the study of the symmetry energy term based on the isoscaling method for such reactions.

Gap uniformity study of a resistive Micromegas for the Multi-purpose Time Projection Chamber (MTPC) at Back-n white neutron source

A Multi-purpose Time Projection Chamber prototype based on a resistive Micromegas technique has been proposed, designed and fabricated at China Spallation Neutron Source to measure the cross sections of neutron-induced light-charged particle emission reactions and fission reactions at the Back-n white neutron source. For the requirements of working stability with high voltage and high granularity of readout, the prototype is fabricated by applying a resistive Micromegas with high-density pixelated anode plane. In order to fully understand the process of charge spreading and signal induction on the anode plane covered by a resistive layer, a simulation method is developed and the energy correction function is then obtained, which can be used in the further energy correction in the experimental data analysis. Measured with a 55Fe X-ray source, the uniformity of gain and avalanche gap are specially analyzed by combining the simulated gas avalanche parameters with fitting of experimental data in which the parallel plate avalanche model is adopted.

Dynamical dipole excitation in the fission of a Ca40 + Sm152 composite system

The excitation of the dynamical dipole mode was explored in the formation of a heavy composite system with mass A≃ 190, by investigating its fission channel. The composite system was produced through the charge asymmetric reaction, Ca40 + Sm152, and the nearly charge symmetric one, Ca48 +Sm144, at Elab = 11 and 10.1 MeV/nucleon, respectively. High-energy γ rays and light charged particles were detected in coincidence with the two fission fragments by means of the MEDEA multidetector array coupled to two parallel plate avalanche counters. The kinetic energy spectra of the light charged particles measured at different angles were used to infer the average excitation energy, the average mass, and the average charge of the produced nuclei whereas the time of flight and the emission angle of the fragments were employed to reconstruct the fission dynamics. The study of the γ-ray spectra and angular distributions for the selected fission events, allowed us to establish (i) the excitation of the giant dipole resonance in the composite system of both reactions and (ii) the excitation of the dynamical dipole mode in the dinucleus of the charge asymmetric reaction by isolating its prompt γ radiation through the difference technique. The present results on the dynamical dipole mode were compared with the experimental findings for the evaporation channel of the Ca40 + Sm152 reaction and moreover with calculations based on a collective bremsstrahlung analysis of the reaction dynamics. Interesting hints connecting the dynamical dipole γ radiation with the superheavy element quest are given.10 MoreReceived 16 February 2022Accepted 6 June 2022DOI:https://doi.org/10.1103/PhysRevC.105.064611©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear reactionsResonance reactionsNuclear Physics

Production of neutron deficient rare earth radionuclides by heavy ion activation

Abstract The attempts to produce neutron deficient radioisotopes of rare Earth elements by heavy ion activation are discussed in this review. The heavy ion induced reaction products have large atomic number difference with that of the target; therefore, radiochemical separation of no-carrier-added radio-lanthanides from the target matrix becomes easier. Heavy ion induced reactions also allow the production of rare Earth radionuclides from non-rare Earth target by tailor-made target-projectile combinations, and in those cases, radiochemical separations become even more easier. In general, the cross sections of heavy ion induced reactions are less than those of light charged particle induced reactions. However, some of the heavy ion induced reactions have comparable cross sections with those of light ion induced reactions. The range of heavy ions is also much smaller in the target matrix than that of lighter charged particles. These points hinder application of heavy ion induced reactions to produce radionuclides for nuclear medicine.

Nuclear data for light charged particle induced production of emerging medical radionuclides

Abstract Whatever the radionuclide to be used in nuclear medicine, it is essential to know the expected yield during the production process, but also of all the possible radionuclidic impurities coproduced, that can have an impact on the product final quality, as well as in the related waste management. The availability of the majority of emerging radioisotopes, including the theranostic ones or pairs, is mainly limited by the fact that, for most of them, the optimal production route still needs to be strengthened if not defined in some cases. The aim of this work is to present a review on the charged particle induced nuclear cross sections to produce some emerging radionuclides for medical applications to show that all types of projectiles should be considered in the quest of producing medical radionuclides. An accurate analysis of the production routes is presented for some radionuclides (67Cu, 47Sc, 89Zr, 103Pd, 186gRe, 97Ru, 211At) chosen as examples to highlight (i) how the quality of the final product strongly depends on the chosen target/projectile/energy parameters set, (ii) how deuteron production routes may sometimes be more effective than the proton ones or lead to a different impurity profile and (iii) how α-particle beams may allow to bypass the limitations occurring when using Z = 1 beams. An overview of possible advantages and drawbacks of the cited production routes and of potential cross sections that still need to be measured, is also reported.

Effect of dissipation coefficient of the K coordinate in dynamical modeling of nuclear fission of 178W produced in fusion reaction

In this paper, a stochastic approach based on two-dimensional dynamical model was used to simulate the fission process of the excited compound nucleus [Formula: see text]W produced in [Formula: see text] reaction. In the dynamical calculations, the elongation parameter of the nucleus was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, [Formula: see text], considered as the second dimension. The average pre-fission multiplicities of neutron, light charged particles and the total kinetic energy of the fission fragments were calculated for [Formula: see text]W and the results of calculations compared with the experimental data over a wide range of excitation energy. In the dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula and the dissipation coefficient of [Formula: see text], was considered as a free parameter and its magnitude inferred by fitting measured data on the average pre-fission multiplicities of neutron and proton for the compound nucleus [Formula: see text]W. It was shown that the results of calculations are in good agreement with the experimental data by using the dissipation coefficient of [Formula: see text] in the range [Formula: see text]. It was also shown that the results of calculations with [Formula: see text] provide a better agreement with the experimental data than with a deformation-dependent dissipation coefficient. Furthermore, it was also shown that differences between the results of calculations for the total kinetic energy of the fission fragments calculated by using different values of dissipation coefficient of [Formula: see text] are small.

Readout system for a prototype multi-purpose time projection chamber at CSNS Back-n

This paper presents a readout system for a prototype multi-purpose Time Projection Chamber (MTPC), which is developed for the research of neutron-induced light-charged particles emission reaction. The prototype MTPC consists of 1521 readout channels for charge measurements, track reconstruction, and neutron time-of-flight measurement. The main function of the readout system is to perform 1521-channel waveform digitization based on multi-channel analog to digital converters (ADCs). Digital waveform compression, multi-board time synchronization, and many other efforts have been made to ensure system performance and stability. Test results show that the readout system has a time resolution better than 10 ns at a trigger rate of 20 kHz. With a 2.8 pC dynamic range of charge measurement, the noise without any input load is around 0.76 fC (in RMS), and the nonlinearity of each channel is less than 0.35%. A beam test with 6Li target has been carried out at the back-streaming white neutron source (Back-n) of China Spallation Neutron Source. The tracks of particles from neutron-induced reactions have been successfully reconstructed. The time-of-flight distribution of the 6Li(n,α)3H reaction reveals the resonance peak at about 240 keV. These results indicate that the readout system fulfils the requirements of the prototype MTPC.

The New Physics in LILITA_N21: An Improved Description of the Reaction 190 MeV 40Ar + 27Al

In this paper, light charged particle emission in the evaporation residue channel for the 190 MeV 40Ar + 27Al reaction leading to 67Ga composite nuclei at Ex = 91 MeV and angular momentum up to 46 ℏ has been re-analyzed. The main goal was to study the decay of 67Ga on the basis of an extended set of observables in order to provide a description of the evaporative decay cascades using the multistep Monte Carlo approach. The proton and α-particle energy spectra along with their angular distributions and ratios of differential multiplicities have been considered. The measured observables were compared with statistical model calculations. Having used a single-step Monte Carlo approach and standard parameters decades ago, the model does not provide a good description of the full dataset. Only a subset of the data was reproduced by assuming emitting nuclei with very large deformed shapes in a previous work published in the late 1980s. In the reported analysis, better agreement has been observed. Using the new transmission coefficients from the Optical Model, the parameters of which have recently been derived, the multi-step approach and the introduction of a nuclear shape description based on the nuclear stratosphere allowed us to realize a significant improvement.

Light charged particle emission from Pb isotopes formed in n-induced channel and related structural analysis

Light charged particle emission from Pb isotopes formed in n-induced channel and related structural analysis

Study of the Proton Irradiation Effects in n-FZ DSSD for the Si Tracker at R3B Experiment

The R3B collaboration aims to assemble an experimental setup with high resolution and efficiency to perform kinematically complete measurements of reactions with high-energy RIBs (radioactive ion beams). In the R3B experimental setup, the silicon tracker is positioned closest to the target region and can provide high-resolution position measurements of light-charged particles like protons. The three layers of the silicon tracker are constructed with a total of 30 Si double-sidedstrip detectors (DSSD). In this paper, as an option of 23 MeV proton irradiated n-type Float-Zone(Fz)Si double-sidedstrip detector (DSSD) havebeen considered, and by taking the two-trapproton irradiation damage model, the bulk damage effect and the macroscopic performance of the Sidouble-sidedstrip detector (DSSD) have been discussed. The detector is irradiated with three values of proton fluences (equivalent to 1Mev neutron fluence): 2×1014,5×1014 and 8×1014 cm-2. By using the Shockley-Read-Hall recombination (SRH) formulation, the full depletion voltage and leakage current have been measured as a function of the irradiation dose, finally the device and process parameters and specifications for the Si double-sidedstrip detector (DSSD) used in the R3B silicon tracker experimenthavebeen proposed.

Nuclear reaction measurements of 80.5 MeV/u [formula omitted]C beam bombarding on C, Cu, W, Au, Pb targets

To get the energy distributions and cross sections of emitted light charged particles, and to explore the nuclear reaction, experiments of 80.5 MeV/u 12C beam bombarding on C, Cu, W, Au, Pb targets have been carried out at Institute of Modern Physics, Chinese Academy of Sciences. 30°, 60°, and 120° relative to the incident beam have been detected using three sets of telescope detectors. The method of ΔE−ΔE−E was used for particle identification. Results indicate that heavier targets have larger double differential cross sections, and the emitted fragments tend to go forward. Besides, the decrease of cross sections of fragments produced with the increasing emitted angles follows a kind of pattern.

Direct Measurement of Carbon Fusion at Astrophysical Energies with Gamma-Particle Coincidences

We present 12C+12C direct fusion measurements with STELLA UKFATIMA, that reach into the region of astrophysics interest relevant to massive stars (M⊙ ≈ 25) using self-supporting thin rotating carbon foils [1]. We demonstrate that detecting gammas and light charged particles in coincidence with nanosecond timing is key for effective background reduction achieving reliable measurements in the sub-nanobarn range. We give details about core developments of the detection apparatus as well as the coincidence-analysis procedure of low count statistics. The present data largely follows the phenomenological hindrance interpolation and shows indication for resonant behaviour at the lowest energy explored.

The emission order of hydrogen isotopes via correlation functions in 30 MeV/u Ar+Au reactions

The intensity interferometry is applied as a chronometer of the particle emission of hydrogen isotopes from the intermediate velocity source formed in 40Ar+197Au reactions at 30 MeV/u. The dynamic emission order of τp>τd>τt is evidenced via the correlation functions of nonidentical particle pairs. Assuming the similar source size, the same emission order is inferred from the correlation functions of identical particle pairs, where τp≈100fm/c is extracted by the fit of Koonin-Pratt equation to p-p correlation function. Transport model simulations demonstrate that the dynamic emission order of light charged particles depends on the stiffness of the nuclear symmetry energy.

Reaction losses of charged particles in CsI(Tl) crystals

To efficiently detect energetic light charged particles, it is common to use arrays of energy-loss telescopes involving two or more layers of detection media. As the energy of the particles increases, thicker layers are usually needed. However, carrying out measurements with thick-telescopes may require corrections for the losses due to nuclear reactions induced by the incident particles on nuclei within the detector and for the scattering of incident particles out of the detector, without depositing their full energy in the active material. In this paper, we develop a method for measuring such corrections and determine the reaction and out-scattering losses for data measured with the silicon-CsI(Tl) telescopes of the newly developed HiRA10 array. The extracted efficiencies are in good agreement with model predictions using the GEANT4 reaction loss algorithm for Z=1 and Z=2 isotopes. After correcting for the HiRA10 geometry, we obtain a general function that describes the loss of efficiency due to reaction losses in CsI(Tl) crystals as a function of range.