Beam Fragmentation Research Articles

Charge exchange processes during carbon ion fragmentation at an energy of 300 MeV/nucleon: comparison with models of ion-ion interactions

Experimental data are presented on the differential cross sections to produce 11Be, 12Be, and 12B isotopes at the carbon beam fragmentation with an energy of 300 MeV/nucleon in the FRAGM experiment conducted based on the ITEP-TWAС multipurpose accelerator complex. The obtained experimental data are compared with the predictions of the models of ion-ion interactions: binary cascade and quantum molecular dynamics model.

Assessment of Crack Resistance of Reinforced Concrete Beam Fragments of Three-layer Floor Slabs

The aim of the work is to study the crack resistance of reinforced concrete beam fragments of three-layer floor slabs. Experimental studies of samples-fragments of reinforced concrete three-layer slabs with an average layer of expanded polystyrene material without internal ribs. Experimental data on crack resistance, formation and development of cracks in fragments and recommendations for calculation are given. Based on the results of experiments, the methodology of the calculation normative standard for the formation of inclined cracks has been refined and supplemented. The coefficient of safety which is included in the formula of the normative standard, taking into account the working conditions of the concrete of the lower layer of fragments of floor slabs, based on the experiments carried out, is recommended to be taken equal to 0.4-0.5

Radioactive ion beam opportunities at the new FRAISE facility of INFN-LNS

At the Laboratori Nazionali del Sud of INFN (INFN-LNS) in Catania, the construction of the new Radioactive Ion Beams (RIBs) facility FRAISE (FRAgment In-flight SEparator) has reached its ending phase. The facility uses the in-flight technique based on a primary beam fragmentation impinging on light Be or C targets. FRAISE makes use of light and medium mass primary beams, having power up to ≈ 2–3 kW, leading to RIBs, whose intensities vary in the range of ≈ 103–107 pps, for nuclei far from and close to the stability valley, respectively. FRAISE aims at providing high-intensity and high-quality RIBs for nuclear physics experiments, also serving to interdisciplinary research areas, such as medical physics. Critical aspects for high-quality beams are the tuning and transport, representing time-consuming processes and requiring dedicated diagnostics and tagging devices measuring many features of RIBs. Some of these devices should be capable to operate in radioactively activated environments because of the expected 2 kW beam lost in the dipole after the production target. Due to its peculiar robustness to radioactive damage, Silicon Carbide (SiC) technology has been considered for the detection layer. In this view, an R&D campaign has been started aiming at developing the FRAISE facility, the new diagnostics system, and a new tagging device, the latter of which will be useful for the CHIMERA multidetector beamline. In this paper, we discuss the status and the perspectives of the facility with a focus on the RIBs opportunities.

The fragmentation trigger of the FOOT experiment

FOOT is a fixed target nuclear physics experiment in which O, C and He beams are shot on H enriched targets to study the projectile fragmentations; the measured cross sections will be used in medical physics and radioprotection in space applications. Beam fragmentation happens only on ≈ 10% of the cases so it is convenient to develop a sophisticated trigger procedure to veto most of non-fragmented primaries passing through the detector.In this paper we present the developed trigger algorithm operated on a WaveDAQ TDAQ system which is used also as DAQ for three of the FOOT detectors.

Fragmentation Measurements in Particle Therapy: status and plans of the FOOT experiment

Due to the advantageous characteristics of the charged particle’s energy deposition in matter, protons or ion beams are used in hadrontherapy to treat deep-seated solid tumors. Using these beams, the maximum of the dose is released to the tumor tissues at the end of the beam range. In this process, nevertheless, fragmentation of both projectile and target nuclei can occur in the nuclear interactions of the beam with the patient tissues and, as showed in recent studies, needs to be carefully taken into account in the delivered dose calculation. Nuclear fragmentation is also extremely relevant for space radioprotection studies, when the exposition of sensors and human crews to solar and galactic particle flows have to be minimized. The goal of the FOOT (FragmentatiOn Of Target) experiment is to estimate target and beam fragmentation performing cross section measurements (with respect to the kinetic energy and direction) with a precision of the order of 5% in the energy range of interest for hadrontherapy (protons in the energy range of 70-230 MeV or ion beams with energy up to 400 MeV/u) and space radioprotection (ion beams with energy up to 800 MeV/u) in order to provide new data for medical physicists, radio-biologists and to improve not only the new generation of oncological Treatment Planning Systems but also the design of shielding elements for the future long duration space missions eventually with human crews. In this paper will be presented the project, the present status of the different detector sub-systems construction and the data-taking plans.

Proceedings to the 7th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA)

Proceedings to the 7th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA)

The FOOT experiment: current status and future perspective for nuclear fragmentation studies in particle therapy and space radiation protection

Nuclear fragmentation processes occurring in the beam-target interaction represent a potential source of hazard for humans’ health both in particle therapy and space exploration. The FragmentatiOn Of Target (FOOT) experiment aims to characterize both beam and target fragments, and to measure with great accuracy nuclear fragmentation cross sections interesting in cancer therapy and in long-lasting interplanetary missions. In this paper, the fragments reconstruction capabilities of the FOOT experimental setup is reported. FOOT future perspective of providing useful data to improve the modelling of neutron interactions is also discussed.

Identification of a new isomeric state in Zn76 following the β decay of Cu76

Background: The evolution of nuclear shell structure far from stability can be explored by identifying and measuring the properties of isomers. Neutron-rich nuclei between the $Z=28$ and the $Z=50$ closed shells have been the subject of recent studies which have identified a number of $0.1--10\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{s}$ isomers and measured detailed spectroscopic properties.Purpose: The purpose of this analysis was to identify and measure the properties of short-lived isomeric states populated following $\ensuremath{\beta}$ decay in $Z\ensuremath{\approx}30,\phantom{\rule{0.28em}{0ex}}N\ensuremath{\approx}50$ nuclei near the doubly magic nucleus $^{78}\mathrm{Ni}$.Methods: Radioactive ions produced by beam fragmentation at the National Superconducting Cyclotron Laboratory were implanted into a ${\mathrm{CeBr}}_{3}$ scintillator coupled to a pixelated photomultiplier tube. Ancillary arrays of HPGe clover and ${\mathrm{LaBr}}_{3}$ detectors were positioned around the implantation detector to measure $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$ rays.Results: The previously observed 2634-keV level in $^{76}\mathrm{Zn}$, populated following the $\ensuremath{\beta}$ decay of $^{76}\mathrm{Cu}$, was identified as isomeric with a half-life of 25.4(4) ns. A combination of timing and $\ensuremath{\gamma}$-ray spectroscopy was used to confirm this assignment. Shell-model calculations were performed and indicate that this state may be a negative-parity state formed by the occupation of the $\ensuremath{\nu}0{g}_{9/2}$ orbital.Conclusions: A new isomeric state in $^{76}\mathrm{Zn}$ has been identified, and its half-life was measured. Ambiguity about the structure of this state could be resolved with further experiments.

Measurement of therapeutic 12C beam in a water phantom using CR-39

The motivation for this study was to explore a new method to test the particle spatial distribution for a therapeutic carbon beam. CR-39 plastic nuclear track detectors were irradiated to a 276.5 MeV u−1 mono-energy carbon beam at the heavy ion facility in the Shanghai Proton and Heavy Ion Center. The spatial distribution of the primary carbon beam and secondary fragments in a water phantom were systematically analyzed both in the transverse direction (perpendicular to the projection direction of the primary beam) and at different depths in the longitudinal direction (along the projection direction of the primary beam) with measured tracks on the CR-39 detectors. Meanwhile, the theoretically spatial distribution and linear energy transfer (LET) spectra of the primary beam and secondary fragments were calculated using the Monte Carlo (MC) toolkit Geant4. The results showed that the CR-39 detectors are capable of providing high lateral resolution of carbon ion at different depths. In the range of the primary carbon beam, the beam width simulated with MC is in good agreement with that of experimental measurement. The track size registered in the CR-39 has a good correlation with the particle LET. These findings indicate that the CR-39 can be used for measuring both the particle flux and its spatial distribution of carbon ions.

Feasibility studies for the measurement of single-spin asymmetry in inclusive K0 s production at pion beam at U-70

In the Spring 2018, the first physics data was accumulated in the new SPASCHARM experiment at U-70 accelerator of IHEP, Protvino. The first stage of SPASCHARM’s physics programs prursues the goal of studying spin effects in the beam fragmentation region at an unpolarized negative 28 GeV beam, interacting with a frozen polarized proton target. In this resport, the feasibility of measuring the single spin asymmetry AN in the reaction: π − + p↑→K 0 S + X is evaluated by Monte-Carlo simulations. We present estimates of the detection efficiency as well as for expected event statistics. It is shown that, in the process of interest above, the attainable statistical errors for AN would be at the scale of a few percents.

Characterization of the PTW-34089 type 147 mm diameter large-area ionization chamber for use in light-ion beams

A newly-designed large-area plane-parallel ionization chamber (of type PTW 34089), denoted BPC150, with a nominal active volume diameter of 147 mm is characterized in this study. Such chambers exhibit benefits compared to smaller chambers in the field of scanned light-ion beam dosimetry because they capture a larger fraction of the laterally-spread beam fragments and ease positioning with respect to small fields. The chamber was characterized in 60Co, 200 kV x-ray, proton and carbon ion beams. The chamber-specific beam-quality correction factor kQ,Q0 was determined. To investigate the homogeneity of the chamber’s response, a radial response map was acquired. An edge correction was applied when the proton beam only partly impinged on the chamber’s active surface. The measured response map showed that the response in the chamber’s center is 3% lower than the average response over the total active area. Furthermore, percentage depth dose (PDD) curves in carbon ions were acquired and compared to those obtained with smaller-diameter chambers (i.e. 81.6 mm and 39.6 mm) as well as with results from Monte Carlo simulations. The measured absorbed dose to water cross calibration coefficients resulted in a kQ,Q0 of 0.981 ± 0.020. Regarding carbon ion PDD curves, relative differences between the BPC150 and smaller chambers were observed, especially for higher energies and in the fragmentation tail. These differences reached 10%–22% in the fragmentation tail (compared to the 81.6 mm diameter chamber). Differences increased when comparing to a chamber with 39.6 mm diameter. The provided results characterize the BPC150 thoroughly for usage in scanned light-ion beam dosimetry and demonstrate its advantage of capturing a larger fraction of the laterally-integrated dose in the fragmentation tail.

A timing RPC with low resistive ceramic electrodes

For precise start time determination a Beam Fragmentation T0 Counter (BFTC) is under development for the Time-of-Flight Wall of the Compressed Baryonic Matter Spectrometer (CBM) at the Facility for Antiproton and Ion Research (FAIR) at Darmstadt/Germany. This detector will be located around the beam pipe, covering the front area of the Projectile Spectator Detector. The fluxes at this region are expected to exceed 105cm−2s−1. Resistive plate chambers (RPC) with ceramic composite electrodes could be use because of their high rate capabilities and radiation hardness of material. Efficiency ≥ 97 %, time resolution ≤ 90 ps and rate capability ≥ 105cm−2s−1 were confirmed during many tests with high beam fluxes of relativistic electrons. We confirm the stability of these characteristics with low resistive Si3N4/SiC floating electrodes for a prototype of eight small RPCs, where each of them contains six gas gaps. The active RPC size amounts 20×20 mm2 produced on basis of Al3O2 and Si3N4/SiC ceramics. Recent test results obtained with relativistic electrons at the linear accelerator ELBE of the Helmholtz-Zentrum Dresden-Rossendorf with new PADI-10 Front-end electronic will be presented.

High-precision mass measurements of Ge and As isotopes near N = Z

High-precision mass measurements of 64,65Ge and 66,67As are presented, which were obtained with the LEBIT (Low Energy Beam Ion Trap) facility at NSCL. The rare isotopes were produced by fast beam fragmentation, slowed down with a high-pressure gas stopping cell and analyzed with LEBIT's Penning-trap mass spectrometer. Compared to previous data, the uncertainties of the masses of 67As and 66As were reduced threefold to 550 eV and five-fold to 5.7 keV, respectively. The mass measurements of 64Ge and 65Ge with respective uncertainties of 40 keV and 4 keV confirm previous LEBIT data. The mass value of the superallowed beta emitter 66As leads to a new QEC value of 9581.5(6.1) keV. Its improvement brings 66As closer to the group of isotopes with well-known Q-values that are used to test the conserved vector current (CVC) hypothesis in searches for physics beyond the Standard Model.

Global analysis of charge exchange meson production at high energies

Many experiments that are conducted to study the hadron spectrum rely on peripheral resonance production. Hereby, the rapidity gap allows the process to be viewed as an independent fragmen- tation of the beam and the target, with the beam fragmentation dominated by production and decays of meson resonances. We test this separation by determining the kinematic regimes that are dominated by factorizable contributions, indicating the most favorable regions to perform this kind of experiments. In doing so, we use a Regge model to analyze the available world data of charge exchange meson production with beam momentum above 5 GeV in the laboratory frame, that are not dominated by either pion or Pomeron exchanges. We determine the Regge residues and point out the kinematic regimes which are dominated by factorizable contributions.

Abstract ID: 241 Geant4 simulation studies of secondary particles emission in hadrontherapy treatments

The aim of this work is the full simulation with Geant4 (vs. 10.0.p03) of secondary particles emitted during an hadrontherapy treatment with 12C. An accurate study of the ion beam fragmentation is important for both the evaluation of secondaries field inside and outside the target volume (i.e. for radioprotection and biological effects evaluation) and the prediction of nuclear particle interactions and their reaction products. In this study we investigate the depth energy deposition (Bragg curve) and the rate of secondary particles produced in the interaction between 12C and targets of different materials (water and Plexiglas). Simple irradiation setup was first implemented for a preliminary comparison of the Geant4 code with literature studies [1,2]. A good agreement (∼0.04%) was found for the Bragg peak position and the peak-to-plateau ratio (∼0.3%). The complete CNAO [3] (Centro Nazionale di Adroterapia Oncologica) extraction beamline with the target water phantom was then simulated for a characterization of secondary particles energy deposition along the beam axis, angular distributions for outgoing protons, neutrons, heavy secondary particles and prompt gammas. An agreement within 0.03% was found for the Bragg peak position with respect to CNAO data and Fluka simulation for 279.97 MeV/u 12C, highlighting the reliability of the Geant4 simulation. Preliminary results agree with literature studies but experimental data are needed to validate the code. Comparisons with additional simulation codes are foreseen. Geant4 simulations studies to predict the development of different physical processes as a function of the beam energy are also ongoing for both protons and carbon ions.

Measurements of 12C ions beam fragmentation at large angle with an Emulsion Cloud Chamber

Hadron radiotherapy is a powerful technique for the treatment of deep-seated tumours. The physical dose distribution of hadron beams is characterized by a small dose delivered in the entrance channel and a large dose in the Bragg peak area. Fragmentation of the incident particles and struck nuclei occurs along the hadron path. Knowledge of the fragment energies and angular distributions is crucial for the validation of the models used in treatment planning systems. We report on large angle fragmentation measurements of a 400 MeV/n 12C beam impinging on a composite target at the GSI laboratory in Germany. The detector was made of 300 micron thick nuclear emulsion films, with sub-micrometric spatial resolution and large angle track detection capability, interleaved with passive material. Thanks to newly developed techniques in the automated scanning of emulsions it was possible to extend the angular range of detected particles. This resulted in the first measurement of the angular and momentum spectrum for fragments emitted in the range from 34̂ to 81̂.

Radiation hard ceramic RPC development

We report recent advances in R&D on the Beam Fragmentation and T0 Counter (BFTC) for the CBM experiment, based on RPCs with floating electrodes made of resistive ceramic material. An optimal value of the ceramics bulk resistivity has been determined to be about 5·109 Ω·cm. RPCs with such electrodes show even characteristics and stable operation under particle fluxes of up to 150 kHz/cm2, with the detection efficiency above 90%.

Study of single-spin asymmetries with polarized target at the SPASCHARM experiment at U70 accelerator

A new experiment SPASCHARM for systematic study of polarization phenomena in inclusive and exclusive hadronic reactions is currently under commissioning at IHEP. The universal experimental setup will detect dozens of various resonances and stable particles produced in collisions of unpolarized beams with the polarized target, and at the next stage, using polarized beams. At the first stage with polarized target, the final states composed of light quarks (u, d, s) will be reconstructed. Hyperon polarization and spin density matrix elements of the vector mesons will be measured along with the single-spin asymmetries. The 2π-acceptance in azimuth, which is extremely useful for reduction of systematic errors in measurements of spin observables, will be implemented in the experiment. The solid angle acceptance of the setup, Δθ≈250 mrad vertically and 350 mrad horizontally in the beam fragmentation region, covers a wide range of kinematic variables pT and xF. This provides the opportunity for separating dependences on these two variables which is usually not possible in the setups with a small solid angle acceptance. Unlike some previous polarization experiments, the SPASCHARM will be able to simultaneously accumulate and record data on the both, charged and neutral particle production.

Systematic Study of Spin Effects at SPASCHARM Experiment at 70-GeV Accelerator in Protvino

A new experiment SPASCHARM for systematic study of polarization phenomena in the inclusive and exclusive hadronic reactions in the energy range of IHEP accelerator U-70 (12–50[Formula: see text]GeV) is currently under development. The universal experimental setup will detect dozens of various resonances and stable particles produced in collisions of unpolarized beams with the polarized target, and at the next stage, using polarized proton and antiproton beams. At the beginning, the final states consisting of light quarks ([Formula: see text], [Formula: see text], [Formula: see text]) will be reconstructed, and later on the charmonium states will be studied. Measurements are planned for a variety of beams: [Formula: see text], antiprotons. Hyperon polarization and spin density matrix elements of the vector mesons will be measured along with the single-spin asymmetry (SSA). The 2[Formula: see text]-acceptance in azimuth, which is extremely useful for reduction of systematic errors in measurements of spin observables, will be implemented in the experiment. The solid angle acceptance of the setup, [Formula: see text] mrad vertically and 350 mrad horizontally in the beam fragmentation region, covers a wide range of kinematic variables [Formula: see text] and [Formula: see text]. This provides the opportunity for separating dependences on these two variables which is usually not possible in the setups with a small solid angle acceptance. Unlike some previous polarization experiments, the SPASCHARM will be able to simultaneously accumulate and record data on the both, charged and neutral particle production.

Simulation of dependence of the cross section of deuterons beam fragmentation into cumulative pions and protons on the mass of the target nucleus

We have studied the mechanisms influencing production of cumulative pions and protons in the fragmentation of the incident deuterons into cumulative pions and protons emitted at zero angle. We argue that the peripheral dependence on the atomic mass of the target nucleus, which was obtained in the experiments for medium and heavy nuclei, can be explained by scattering on target nucleons without introducing additional parameters.