Nuclear Fragmentation Processes Research Articles

Features of the Organization of the Tegument in Cystacanth and Adult Acanthocephalan <i>Acanthocephalus tenuirostris</i>

A comparative light- and electron-microscopic study of the tegument of a formed cystacanth and a mature acanthocephalan Acanthocephalus tenuirostris (Achmerov et Dombrowskaja – Achmerova, 1941) was carried out. It was shown that, in addition to morphometric differences, the tegument of cystacanth differs from that of the adult acanthocephalan by terminal expansions of invaginates of the outer tegument membrane, presumably due to the secretion of glycocalyx material. In the tegument of an adult acanthocephalan, a process of detachment from the nuclei of small fragments was found, which may be an analogue of the well-known process of nuclear fragmentation that occurs at the early stages of postembryonic development. It has been shown that in many cases tegument lacunae are not completely limited by dense formations resembling fibrils on sections.

Nuclear fragmentation cross section measurements with the FOOT experiment

FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment that aims at a full characterization of the nuclear fragmentation processes of interest for Particle Therapy and Radiation Protection in Space. The physics program foresees a set of measurements in direct and inverse kinematics using particle beams and targets with composition similar to human tissues and spacecraft shielding materials. The final goal of the experiment is the measurement of double differential cross sections with respect to angle and fragment energy in the 100-800 MeV/u range with a precision better than 5%. The FOOT Collaboration is currently completing the development of the apparatus and data acquisition campaigns with partial setups have already started. In this paper, an overview of the current status of the experiment is given, together with a summary of the preliminary results obtained from the first measurements with 16O beams.

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.

The FragmentatiOn Of Target (FOOT) Experiment and Its DAQ System

The FragmentatiOn mymargin Of Target (FOOT) experiment aims to provide precise nuclear cross section measurements for two different fields: hadrontherapy and radio-protection in space. The main reason is the important role the nuclear fragmentation process plays in both fields, where the health risks caused by radiation are very similar and mainly attributable to the fragmentation process. The FOOT experiment has been developed in such a way that the experimental setup is easily movable and fits the space limitations of the experimental and treatment rooms available in hadrontherapy treatment centers, where most of the data takings are carried out. The trigger and data acquisition system needs to follow the same criteria and it should work in different laboratories and different conditions. It has been designed to acquire high statistics samples to fulfill the accuracy requirements of the physics analysis. Data-taking is being monitored online to allow the shift crew to verify the correct functioning of the system.

Enhancing the understanding of fragmentation processes in hadrontherapy and radioprotection in space with the FOOT experiment

During proton and carbon ions cancer treatment, nuclear interactions of the beam nuclei with the patient tissues always occur: the former leads to target fragmentation only, the latter to both projectile and target fragments production. In proton therapy the low-energy, high-charge and therefore short-range fragments produced along the beam path in the target fragmentation process may have higher biological effectiveness compared to protons, resulting in a not negligible effect on the delivered dose in a region before the tumor site. In carbon treatments the long range of projectile fragments results in a dose deposition in the healthy tissues behind the tumor site. Therefore, precise fragmentation cross section data would be of great importance to further optimize treatments. At the same time, such data would help improving the design of the shielding of spaceships, especially in view of long distance travels (i.e. Mars human exploration). In fact, nuclear fragmentation occurring between the space background radiation and spacecrafts materials changes the composition of the radiation field and thus the dose received by the astronauts. The FOOT (FragmentatiOn Of Target) experiment has been designed to investigate nuclear fragmentation processes of interest for particle therapy and space radiation protection with a precision in the cross section measurements around 5%. In this work the physics motivations of FOOT and the final design of the experiment will be presented. A performances study of the electronic setup based on FLUKA Monte Carlo simulations and a preliminary analysis of experimental data are reported as well.

Charge identification of nuclear fragments with the FOOT Time-Of-Flight system

FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment conceived to conduct high-precision cross section measurements of nuclear fragmentation processes relevant for particle therapy and radiation protection in space. These measurements are important to estimate the physical and biological effects of nuclear fragments, which are produced when energetic particle beams penetrate human tissue.A component of the FOOT experiment is the ΔE-TOF system. It is designed to measure energy loss and time-of-flight of nuclear fragments produced in particle collisions in thin targets in order to extract their charge and velocity. The ΔE-TOF system is composed of a start counter, providing the start time for the time-of-flight, and a 40 × 40 cm2 wall of thin plastic scintillator bars, providing the arrival time and energy loss of the fragments passing through the detector. Particle charge discrimination can be achieved by correlating the energy loss in the scintillator bars with the measured time-of-flight.Recently, we have built a full-size ΔE-TOF detector. In this work, we describe the energy and time-of-flight calibration procedure and assess the performance of this system. We use data acquired during beam tests at CNAO with proton and 12C beams and at GSI with 16O beams in the energy range relevant for particle therapy, i.e., from 60 to 400 MeV/u. For heavy fragments (C and O), we obtain energy and time resolutions ranging from 4.0 to 5.2% and from 54 to 76 ps, respectively. The procedure is also applied to a fragmentation measurement of a 400 MeV/u 16O beam on a 5 mm carbon target, showing that the system is able to discriminate the charges of impinging fragments.

Measuring the Impact of Nuclear Interaction in Particle Therapy and in Radio Protection in Space: the FOOT Experiment

In Charged Particle Therapy (PT) proton or 12C beams are used to treat deep-seated solid tumors exploiting the advantageous characteristics of charged particles energy deposition in matter. For such projectiles, the maximum of the dose is released at the end of the beam range, in the Bragg peak region, where the tumour is located. However, the nuclear interactions of the beam nuclei with the patient tissues can induce the fragmentation of projectiles and/or target nuclei and needs to be carefully taken into account when planning the treatment. In proton treatments, the target fragmentation produces low energy, short range fragments along all the beam path, that deposit a non-negligible dose especially in the first crossed tissues. On the other hand, in treatments performed using 12C, or other (4He or 16O) ions of interest, the main concern is related to the production of long range fragments that can release their dose in the healthy tissues beyond the Bragg peak. Understanding nuclear fragmentation processes is of interest also for radiation protection in human space flight applications, in view of deep space missions. In particular 4He and high-energy charged particles, mainly 12C, 16O, 28Si and 56Fe, provide the main source of absorbed dose in astronauts outside the atmosphere. The nuclear fragmentation properties of the materials used to build the spacecrafts need to be known with high accuracy in order to optimise the shielding against the space radiation. The study of the impact of these processes, which is of interest both for PT and space radioprotection applications, suffers at present from the limited experimental precision achieved on the relevant nuclear cross sections that compromise the reliability of the available computational models. The FOOT (FragmentatiOn Of Target) collaboration, composed of researchers from France, Germany, Italy and Japan, designed an experiment to study these nuclear processes and measure the corresponding fragmentation cross sections. In this work we discuss the physics motivations of FOOT, describing in detail the present detector design and the expected performances, coming from the optimization studies based on accurate FLUKA MC simulations and preliminary beam test results. The measurements planned will be also presented.

ПОРІВНЯЛЬНА ОЦІНКА ВЕЛИЧИНИ АНТИАПОПТОТИЧНОГО ЕФЕКТУ СЕРЕД МОДУЛЯТОРІВ АКТИВНОСТІ NMDA-РЕЦЕПТОРІВ В УМОВАХ МОДЕЛЬНОЇ ПЕРЕХІДНОЇ ІШЕМІЇ РЕПЕРФУЗІЇ ОКА ЗА ДАНИМИ ПРОТОКОВО-ЦИТОМЕТРИЧНОГО АНАЛІЗУ

Модельна 60 хв. ішемія-реперфузія ока у щурів супроводжується активацією апоптотичних процесів в сітківці, про що достеменно свідчить збільшення в середньому в 20,22 раза пулу клітин, які перебувають у фазі SUB-G0G1, тобто мають ознаки фрагментації ядерної ДНК, що анонсує апоптоз. Однократна внутрішньовенна інфузія в лікувальному режимі через 30 хв після накладання лігатур розчинів амантадину або магнію сульфату, дозами 5 та 250 мг/кг відповідно, а також мемантин перорально з розрахунку 20 мг/кг, сприяють зменшенню відносної кількості ретиноцитів, які перебувають фазі SUB-G0G1 клітинного циклу, проявляючи тим самим антиапоптотичну дію. За спроможністю в умовах даної патології знижувати процес фрагментації ядерної ДНК, застосування розчину амантадину сульфату вірогідно переважає терапію розчином магнію сульфату або мемантином в середньому на 24,1 та 52,0 % відповідно.

In vitro Anticancer Activities of Ethanolic Extracts of Dendrobium crepidatum and Dendrobium chrysanthum against T-cell lymphoma

Background: The orchid plants of Dendrobium, belong to the largest family of flowering plants orchidaceae. The genus Dendrobium reported to possess various therapeutic activities including anticancer activity. In the present scenario, cancer is one of the most leading causes of death worldwide. Therefore, the main objective of the present study was to demonstrate the cytotoxic and apoptotic inducing activity of Dendrobium crepidatum and Dendrobium chrysanthum ethanolic extracts in T-cell lymphoma. Methods: MTT assay was done to evaluate the cytotoxic effect of the extracts on lymphoma cells. The reactive oxygen species (ROS) generation by the ethanolic extracts was also examined by DCFH-DA. Fluorescence microscopy studies and DNA fragmentation assay were done to investigate the apoptotic cell death. Flow cytometry was done to check the effect of ethanolic extracts on cell cycle phase distribution. Results: The results revealed that both the extracts led to dose dependent cytotoxic effect in T-cell lymphoma along with increased generation of intracellular reactive oxygen species in a dose and time dependent manner. The fluorescent microscopic studies showed that the extracts induced cellular shrinkage, chromatin condensation and nuclear fragmentation, the major hallmarks of apoptosis, in dose dependent manner. The presence of DNA ladder further confirms the process of nuclear fragmentation, and the cell cycle analysis showed significant delay at G2/M phase of the cell cycle with both the extracts. Conclusion: The whole study suggests that Dendrobium crepidatum and Dendrobium chrysanthum ethanolic extracts induced substantial cytotoxic and apoptotic activity in T-cell lymphoma. Therefore, further studies are needed to establish the detailed mechanism of anticancer activity of both the ethanolic extracts.

Characteristics of disintegration of different emulsion nuclei by relativistic 28Si nuclei at 3.7 A GeV

An analysis of the data based on 924 inelastic interaction events induced by 28Si nuclei in a nuclear emulsion is presented. The nuclear fragmentation process is studied by analysing the total charge (Q) distribution of the projectile spectators for different emulsion target groups along with the comparison of Monte Carlo Glauber model results. Probability distributions for total disintegrated events as a function of different projectile masses are shown and compared with cascade evaporation model results at same energy per nucleon. Further, mean multiplicities of different charged secondaries for different classes of events are presented and for each event, variation of mean multiplicities as a function of total charge (Q) is also presented. The pseudorapidity distributions and normalized pseudorapidity distributions of the produced charged particles in nucleus–nucleus collisions at 3.7 A GeV are analysed for total disintegration (TD) as well as minimum-bias events.

Performance of the reconstruction algorithms of the FIRST experiment pixel sensors vertex detector

Hadrontherapy treatments use charged particles (e.g. protons and carbon ions) to treat tumors. During a therapeutic treatment with carbon ions, the beam undergoes nuclear fragmentation processes giving rise to significant yields of secondary charged particles. An accurate prediction of these production rates is necessary to estimate precisely the dose deposited into the tumours and the surrounding healthy tissues. Nowadays, a limited set of double differential carbon fragmentation cross-section is available. Experimental data are necessary to benchmark Monte Carlo simulations for their use in hadrontherapy. The purpose of the FIRST experiment is to study nuclear fragmentation processes of ions with kinetic energy in the range from 100 to 1000MeV/u. Tracks are reconstructed using information from a pixel silicon detector based on the CMOS technology. The performances achieved using this device for hadrontherapy purpose are discussed. For each reconstruction step (clustering, tracking and vertexing), different methods are implemented. The algorithm performances and the accuracy on reconstructed observables are evaluated on the basis of simulated and experimental data.

Comparison of PHITS, GEANT4, and HIBRAC simulations of depth-dependent yields of β+-emitting nuclei during therapeutic particle irradiation to measured data

For quality assurance in particle therapy, a non-invasive, in vivo range verification is highly desired. Particle therapy positron-emission-tomography (PT-PET) is the only clinically proven method up to now for this purpose. It makes use of the β+-activity produced during the irradiation by the nuclear fragmentation processes between the therapeutic beam and the irradiated tissue. Since a direct comparison of β+-activity and dose is not feasible, a simulation of the expected β+-activity distribution is required. For this reason it is essential to have a quantitatively reliable code for the simulation of the yields of the β+-emitting nuclei at every position of the beam path. In this paper results of the three-dimensional Monte-Carlo simulation codes PHITS, GEANT4, and the one-dimensional deterministic simulation code HIBRAC are compared to measurements of the yields of the most abundant β+-emitting nuclei for carbon, lithium, helium, and proton beams. In general, PHITS underestimates the yields of positron-emitters. With GEANT4 the overall most accurate results are obtained. HIBRAC and GEANT4 provide comparable results for carbon and proton beams. HIBRAC is considered as a good candidate for the implementation to clinical routine PT-PET.

FIRST experiment: Fragmentation of Ions Relevant for Space and Therapy

Nuclear fragmentation processes are relevant in different fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at SIS accelerator of GSI laboratory in Darmstadt, has been designed for the measurement of different ions fragmentation cross sections at different energies between 100 and 1000 MeV/nucleon. The experiment is performed by an international collaboration made of institutions from Germany, France, Italy and Spain. The experimental apparatus is partly based on an already existing setup made of the ALADIN magnet, the MUSIC IV TPC, the LAND2 neutron detector and the TOFWALL scintillator TOF system, integrated with newly designed detectors in the interaction Region (IR) around the carbon removable target: a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger for detection of light fragments emitted at large angles (KENTROS). The scientific program of the FIRST experiment started on summer 2011 with the study of the 400 MeV/nucleon 12C beam fragmentation on thin (8mm) carbon target.

The FIRST experiment at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the SIS accelerator of GSI laboratory in Darmstadt has been designed for the measurement of ion fragmentation cross-sections at different angles and energies between 100 and 1000MeV/nucleon. Nuclear fragmentation processes are relevant in several fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications.The start of the scientific program of the FIRST experiment was on summer 2011 and was focused on the measurement of 400MeV/nucleon 12C beam fragmentation on thin (8mm) graphite target.The detector is partly based on an already existing setup made of a dipole magnet (ALADiN), a time projection chamber (TP-MUSIC IV), a neutron detector (LAND) and a time of flight scintillator system (TOFWALL). This pre-existing setup has been integrated with newly designed detectors in the Interaction Region, around the carbon target placed in a sample changer. The new detectors are a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger scintillator system optimized for the detection of light fragments emitted at large angles.In this paper we review the experimental setup, then we present the simulation software, the data acquisition system and finally the trigger strategy of the experiment.

Design Guidelines for a Double Scattering Compton Camera for Prompt-$\gamma$ Imaging During Ion Beam Therapy: A Monte Carlo Simulation Study

In hadrontherapy in order to fully take advantage of the assets of the ion irradiation, the position of the Bragg peak has to be monitored accurately. Here, we investigate a monitoring method relying on the detection in real time of the prompt γ emitted quasi instantaneously during the nuclear fragmentation processes. Our detection system combines a beam hodoscope and a double scattering Compton camera. The prompt-γ emission points are reconstructed by intersecting the ion trajectories given by the hodoscope and the Compton cones reconstructed with the camera. We propose here to study in terms of point spread function and efficiency the theoretical feasibility of the emission points reconstruction with our set-up in the case of a photon point source in air. First we analyze the nature of all the interactions which are likely to produce an energy deposit in the three detectors of the camera. It is underlined that upper energy thresholds in both scatter detectors are required in order to select mainly Compton events (one Compton interaction in each scatter detector and one interaction in the absorber detector). Then, we study the influence of various parameters such as the photon energy and the inter-detector distances on the Compton camera response. These studies are carried out by means of Geant4 simulations. We use a source with a spectrum corresponding to the prompt-γ spectrum emitted during the carbon ion irradiation of a water phantom. In the current configuration, the spatial resolution of the Compton camera is about 6 mm (Full Width at Half Maximum) and the detection efficiency 10-5. Finally, provided the detection efficiency is increased, the clinical applicability of our system is considered.

Nuclear interactions in heavy ion transport and event-based risk models

The physical description of the passage of heavy ions in tissue and shielding materials is of interest in radiobiology, cancer therapy and space exploration, including a human mission to Mars. Galactic cosmic rays (GCRs) consist of a large number of ion types and energies. Energy loss processes occur continuously along the path of heavy ions and are well described by the linear energy transfer (LET), straggling and multiple scattering algorithms. Nuclear interactions lead to much larger energy deposition than atomic-molecular collisions and alter the composition of heavy ion beams while producing secondary nuclei often in high multiplicity events. The major nuclear interaction processes of importance for describing heavy ion beams was reviewed, including nuclear fragmentation, elastic scattering and knockout-cascade processes. The quantum multiple scattering fragmentation model is shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections and is studied for application to thick target experiments. A new computer model, which was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL), called the GCR Event Risk-Based Model (GERMcode) is described.

CHARGE AND MASS CHANGING CROSS-SECTIONS OF 158A GeV Pb PROJECTILES ON Al, Cu, Bi, AND Pb TARGETS: FRAGMENTATION PROCESSES

We report here on total and partial charge changing cross-sections of 158A GeV lead projectiles on Al , Cu , Pb and Bi stationary targets using CR-39 detectors. Present results are compared with relevant published results. Deep discussion of nuclear fragmentation processes is provided. Stacks of CR-39 Track Detectors with above-mentioned targets were exposed to 158 A GeV 207 Pb projectiles at the CERN-SPS beam facility at normal incidence with a fluence of about 1500 ions/cm 2. Lengths of etched cones on one face of the CR-39 detectors before and after the target were measured for each stack. These measurements were used for determination of total and partial charge changing cross-sections of 158 A GeV Pb 82+ projectiles on these targets in the charge region 63 < Z < 82. The charge resolution (σZ) achieved in the present experiment is ~0.18e. Mass changing cross-sections are derived from the measured charge changing cross-sections using hyper-geometric relationship. A new method is proposed for separate measurements of electromagnetic and nuclear parts of fragmentation cross-sections using ion channeling and blocking conditions of projectiles in crystalline targets.

Features Study on Target Fragmentation in the Collisions Of 24Mg and 28Si with Emulsion Nuclei at 3.7A GeV

Problem statement: The process of nuclear fragmentation in interactions of 3.7A GeV 24Mg and 28Si nuclei with the different target nuclei in a nuclear emulsion have been investigated. Approach: The probability of interactions without any projectile fragment with charge Z≥2 is zero for hydrogen target, but increases by increasing the mass of the target. Results: The disruption of a projectile nucleus is more save in interactions with the heavy target nuclei than with the light ones. The nuclear fragmentation mechanism was investigated for shower and slow particles at Dubna energy. Several correlations between these particles are studied and analyzed. The variation of ng>/ns> with Nh behaves a straight line up to Nh = 14 in the collision of 24Mg and 28Si with emulsion nuclei, it reaches to constant value. These results are contradicted with that obtained from the light projectile nuclei such as p, d, 4He and 7Li with emulsion nuclei at the same energy. Conclusion: The behavior of the scale shower (s>P (ns /s>) and compound (c>P (nc/c>) where (nc = ns+ng) particles are the same, also for both the collisions of 24Mg and 28Si with nuclei give the same behavior.

Chaos analysis of nuclear fragments in high energy collisions

This paper deals with fixed target AGS and SPS data of beam energies 14.5 and 200 A GeV respectively. A detailed study on chaos in the nuclear fragmentation process of 28Si–AgBr interactions at 14.5 A GeV and 32S–AgBr interactions at 200 A GeV has been performed using a new parameter, the entropy index. The analysis provides new data on the evidence of the erratic behavior of the target fragments signifying chaotic target fragmentation and also quantify the measure for chaos in high and ultra-high energy heavy-ion interactions. Further, it is also observed that the target fragmentation process becomes less chaotic with the increase of average multiplicities of the final states.

Determination of important nuclear fragmentation processes for human space radiation protection

We present a semi-analytical method to determine which partial cross sections of nuclear fragmentations most affect the shielded dose equivalent due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies in order for us to better predict, reduce and mitigate the radiation exposure in human space explorations.