12C Ion Beams Research Articles

Addendum: Measurement of charged particle yields from PMMA irradiated by a 220 MeV/u 12C beam

In this paper we report the re-analysis of the data published in Piersanti et al (2014 Phys. Med. Biol. 59 1857) documenting the charged secondary particles production induced by the interaction of a 220 MeV/u 12C ion beam impinging on a polymethyl methacrylate (PMMA) target, measured in 2012 at the GSI facility in Darmstadt (Germany). This re-analysis takes into account the inhomogeneous light response of the LYSO crystal in the experimental setup measured in a subsequent experiment (2014) performed in the Heidelberg Ion-Beam Therapy Center. A better description of the detector and re-calculation of the geometrical efficiencies have been implemented as well, based on an improved approach that accounts also for the energy dependence of the emission spectrum.The new analysis has little effect on the total secondary charged flux, but has an impact on the production yield and emission velocity distributions of the different particle species (protons, deuterons and tritons) at different angles with respect to the beam direction ( and ). All these observables indeed depend on the particle identification algorithms and hence on the LYSO detector energy response.The results of the data re-analysis presented here are intended to supersede and replace the results published in Piersanti et al (2014 Phys. Med. Biol. 59 1857).

Validation of Geant4 fragmentation for Heavy Ion Therapy

12C ion therapy has had growing interest in recent years for its excellent dose conformity. However at therapeutic energies, which can be as high as 400 MeV/u, carbon ions produce secondary fragments. For an incident 400 MeV/u 12C ion beam, ∼70% of the beam will undergo fragmentation before the Bragg Peak. The dosimetric and radiobiological impact of these fragments must be accurately characterised, as it can result in increasing the risk of secondary cancer for the patient as well as altering the relative biological effectiveness. This work investigates the accuracy of three different nuclear fragmentation models available in the Monte Carlo Toolkit Geant4, the Binary Intranuclear Cascade (BIC), the Quantum Molecular Dynamics (QMD) and the Liege Intranuclear Cascade (INCL++). The models were benchmarked against experimental data for a pristine 400 MeV/u 12C beam incident upon a water phantom, including fragment yield, angular and energy distribution. For fragment yields the three alternative models agreed between ∼5 and ∼35% with experimental measurements, the QMD using the “Frag” option gave the best agreement for lighter fragments but had reduced agreement for larger fragments. For angular distributions INCL++ was seen to provide the best agreement among the models for all elements with the exception of Hydrogen, while BIC and QMD was seen to produce broader distributions compared to experiment. BIC and QMD performed similar to one another for kinetic energy distributions while INCL++ suffered from producing lower energy distributions compared to the other models and experiment.

Deconvolution study on the glow curve structure of LiF:Mg,Ti and LiF:Mg,Cu,P thermoluminescent detectors exposed to 1H, 4He and 12C ion beams

Lithium fluoride represents the most frequently used base material for thermoluminescent detectors. The glow curve of these detectors is composed of a series of peaks which intensities strongly depend on the given dose, the type and energy of the impinging radiation, the concentration of dopants in the crystal and the lithium isotopic concentration.In this work, 6LiF:Mg,Ti, 7LiF:Mg,Ti, 6LiF:Mg,Cu,P and 7LiF:Mg,Cu,P detectors were exposed to calibrated hydrogen, helium and carbon ion beams in order to investigate the change of the structure of the different peaks composing the glow curves of these materials and their relative luminescence efficiency. In order to resolve the different peak contributions, computer assisted deconvolution of the glow curve was performed and the used sets of parameters (activation energy E and temperature at peak maximum Tmax) are presented.In the case of LiF:Mg,Ti detectors, the low temperature peaks and the main peak are characterized by a general efficiency decrease with the increase of the LET of the incident particle. No remarkable differences were found between detectors enriched with 6Li or 7Li. On the other hand, differences in the structure of the high temperature peaks between the two lithium isotopic compositions were found and discussed. Regarding LiF:Mg,Cu,P detectors, each peak shows a general monotonously decreasing relative efficiency with the increase of LET. In this case, a similar LET dependence was found between 6Li and 7Li based detectors. Furthermore, unusual efficiencies greater than 1 for the low temperature peaks of LiF:Mg,Cu,P exposed to low LET particle were observed.

Correction factors to convert microdosimetry measurements in silicon to tissue in 12C ion therapy

Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic 12C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length to calculate the lineal energy was introduced as an alternative to the mean chord length because it was found that adopting Cauchy’s formula for the was not appropriate for the radiation field typical of HIT as it is very directional. can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident 12C ion beam can be adopted as . The tissue equivalence conversion method and were adopted to determine the RBE10, calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of the determination of .

RBE study using solid state microdosimetry in heavy ion therapy

The response of two types of 10 μm thick silicon-on-insulator (SOI) detectors in a 12C ion therapy beam with extremely high spatial resolution are presented in this work. The two detectors used are the “bridge” microdosimeter with isolated 3D sensitive volumes (SVs) and the ultra-thin 3D (U3DTHIN) detector with n+ and p+ 3D columnar structures. Both detectors were investigated at various depths in a water phantom along the central axis of the spread-out Brag peak (SOBP) of a 290 MeV/u 12C ion beam at the Heavy Ion Medical Accelerator in Chiba, Japan. Based on the Microdosimetric Kinetic (MK) model and the microdosimetric quantities measured with the two detectors, the relative biological effectiveness (RBE) values were derived and compared to results obtained with the tissue-equivalent proportional counter (TEPC). Derived RBE10 values obtained with the U3DTHIN detector were considerably higher than those obtained with the bridge microdosimeter and the TEPC along the SOBP. Due to the high spatial resolution of the microdosimeters, more detailed measurements were obtained at the end of the SOBP compared to the TEPC. The maximum derived RBE10 found using the U3DTHIN detector and bridge microdosimeter were approximately 2.66 and 2.58, respectively which are higher than the RBE10 value of 2.35 obtained with the TEPC due to the lack of high spatial resolution in the TEPC. The discrepancy in the results obtained using the two detectors is due to the difference in geometry of the SVs in the two detectors. This work presents an application of different types of SOI micodosimeters in a 12C ion therapy beam and has demonstrated that the microdosimeter with micron sized 3D SVs is more desirable for accurate lineal energy measurement and RBE determination. Silicon microdosimetry has demonstrated a simple, fast and accurate method for routine Quality Assurance in charged particle therapy.

Secondary radiation measurements for particle therapy applications: prompt photons produced by 4He, 12C and 16O ion beams in a PMMA target

Charged particle beams are used in particle therapy (PT) to treat oncological patients due to their selective dose deposition in tissues with respect to the photons and electrons used in conventional radiotherapy. Heavy (Z > 1) PT beams can additionally be exploited for their high biological effectiveness in killing cancer cells. Nowadays, protons and carbon ions are used in PT clinical routines. Recently, interest in the potential application of helium and oxygen beams has been growing. With respect to protons, such beams are characterized by their reduced multiple scattering inside the body, increased linear energy transfer, relative biological effectiveness and oxygen enhancement ratio.The precision of PT demands online dose monitoring techniques, crucial to improving the quality assurance of any treatment: possible patient mis-positioning and biological tissue changes with respect to the planning CT scan could negatively affect the outcome of the therapy. The beam range confined in the irradiated target can be monitored thanks to the neutral or charged secondary radiation emitted by the interactions of hadron beams with matter. Among these secondary products, prompt photons are produced by nuclear de-excitation processes, and at present, different dose monitoring and beam range verification techniques based on prompt-γ detection are being proposed. It is hence of importance to perform γ yield measurement in therapeutic-like conditions.In this paper we report on the yields of prompt photons produced by the interaction of helium, carbon and oxygen ion beams with a poly-methyl methacrylate (PMMA) beam stopping target. The measurements were performed at the Heidelberg Ion-Beam Therapy Center (HIT) with beams of different energies. An LYSO scintillator, placed at and with respect to the beam direction, was used as the photon detector. The obtained γ yields for the carbon ion beams are compared with results from the literature, while no other results from helium and oxygen beams have been published yet. A discussion on the expected resolution of a slit camera detector is presented, demonstrating the feasibility of a prompt-γ-based monitoring technique for PT treatments using helium, carbon and oxygen ion beams.

Effects of Ion Irradiation on Seedlings Growth Monitored by Ultraweak Delayed Luminescence.

The optical technique based on the measurement of delayed luminescence emitted from the biological samples has demonstrated its ability to provide valid and predictive information on the functional status of various biological systems. We want to extend this technique to study the effect of ionizing radiation on biological systems. In particular we are interested in the action of ion beams, used for therapeutic purposes or to increase the biological diversity. In general, the assessment of the damage that radiation produces both in the target objects and in the surrounding tissues, requires considerable time because is based on biochemical analysis or on the examination of the evolution of the irradiated systems. The delayed luminescence technique could help to simplify this investigation. We have so started our studies performing irradiations of some relatively simple vegetable models. In this paper we report results obtained from mung bean (Vigna radiata) seeds submitted to a 12C ion beam at the energy of 62 MeV/nucleon. The dry seeds were irradiated at doses from 50 to 7000 Gy. The photoinduced delayed luminescence of each seed before and after ion irradiation was measured. The growth of seedlings after irradiation was compared with that of untreated seeds. A growth reduction on increasing the dose was registered. The results show strong correlations between the ion irradiation dose, seeds growth and delayed luminescence intensity. In particular, the delayed luminescence intensity is correlated by a logistic function to the seedlings elongation and, after performing a suitable measurement campaign based on blind tests, it could become a tool able to predict the growth of seeds after ion irradiation. Moreover these results demonstrate that measurements of delayed luminescence could be used as a fast and non-invasive technique to check the effects of ion beams on relatively simple biological systems.

Simulations and Test Results of Large Area Continuous Position Sensitive Diamond Detectors

Continuous Position Sensitive Diamond Detector (CPSDD) development started by using the single crystal (sc) diamond material. The intrinsic high detection efficiency of sc diamond, providing a high Signal to Noise (S/N) ratio, allowed the full testing of CPSDD with α-particles. However, due to the size limitations of sc diamond, the development of Large Area CPSDD (LACPSDD) naturally evolved towards the use of polycrystalline (pc) diamond material, produced by chemical vapor deposition (CVD). The charge generated by the particle or radiation impact is collected through diamond like carbon (DLC) layers and associated metallic electrodes deposited on the sides of the pc diamond plate. The incident particle position can be obtained via charge division measurement by using charge sensitive amplifiers (CSA) connected to each electrode. In this paper we report the improvement in LACPSDD design by showing results obtained for two pc diamond detector (pcDD) structures. The first pcDD has a DLC layer with four electrodes at the corners of the front side, whereas the back side is fully metallized. The second pcDD has DLC layers on both sides of the detector plate, each equipped with two parallel electrode strips, along the x and y axis, respectively. Experimental results on the first pcDD showed an ion rate limitation, caused by the increase in the detector time constant (because of the larger detection area), and a low S/N ratio, due to the specific reduced signal associated with low Charge Collection Efficiency (CCE) of pc diamond. Subsequently, by using an optimized electronics and a better pc diamond (higher CCE), the second pcDD shows a higher S/N ratio, as well as a lower time constant. This paper presents simulation results on the time constant and an analytical evaluation of the S/N ratio, which serve to optimize the pc LACPSDDs. We also show experimental test results with α-particles, as well as 54Ni (1.7 AGeV) and 12C (11.4 AMeV) ion beams. Prime Novelty StatementThis paper presents the first large area continuous position sensitive diamond detectors implemented on polycrystalline CVD diamond material for single ionizing particle detection.

Comparisons of longitudinal and lateral dose profiles and relative biological effectiveness for DNA double strand breaks among 1H, 4He and 12C beams

Monte Carlo FLUKA and MCDS codes were used to study 1H, 4He and 12C ion beams with similar ranges in water phantom. The longitudinal and lateral dose profiles and the relative biological effectiveness (RBE) were investigated. Simulations were performed with particular emphasis in the vicinity of the Bragg peak (BP). The impact of individual nuclear fragments created by the primary beams was examined. Comparisons were made for the BP width, lateral dose profile width, and RBE value at different depths in the phantom. RBE values for the induction of DNA double-strand breaks were estimated, particularly in the vicinity of the BP. Results showed that 12C beam had the narrowest BP width, smallest lateral dose profile, and largest RBE value, followed by 4He and 1H beams. However, the differences between 4He and 12C were smaller than those between 1H and 4He. It also showed that the influence of nuclear fragments was significant for 12C beam, moderate for 4H beam, and minor for 1H beam. This influence was important for 12C at depths beyond the BP. Our results suggest that 4He beam is also a promising option for cancer therapy.

Production of pure quasi-monochromatic 11C beams for accurate radiation therapy and dose delivery verification

In the present study we develop a new technique for the production of clean quasi-monochromatic 11C positron emitter beams for accurate radiation therapy and PET–CT dose delivery imaging and treatment verification. The 11C ion beam is produced by projectile fragmentation using a primary 12C ion beam. The practical elimination of the energy spread of the secondary 11C fragments and other beam contaminating fragments is described. Monte Carlo calculation with the SHIELD-HIT10+ code and analytical methods for the transport of the ions in matter are used in the analysis. Production yields, as well as energy, velocity and magnetic rigidity distributions of the fragments generated in a cylindrical target are scored as a function of the depth within 1cm thick slices for an optimal target consisting of a fixed 20cm section of liquid hydrogen followed by a variable thickness section of polyethylene. The wide energy and magnetic rigidity spread of the 11C ion beam can be reduced to values around 1% by using a variable monochromatizing wedge-shaped degrader in the beam line. Finally, magnetic rigidity and particle species selection, as well as discrimination of the particle velocity through a combined Time of Flight and Radio Frequency-driven Velocity filter purify the beam from similar magnetic rigidity contaminating fragments (mainly 7Be and 3He fragments). A beam purity of about 99% is expected by the combined method.

Dosimetry in radiobiological studies with the heavy ion beam of the Warsaw cyclotron

The aim of this study was to verify various dosimetry methods in the irradiation of biological materials with a 12C ion beam at the Heavy Ion Laboratory of the University of Warsaw. To this end the number of ions hitting the cell nucleus, calculated on the basis of the Si-detector system used in the set-up, was compared with the number of ion tracks counted in irradiated Solid State Nuclear Track Detectors and with the number of ion tracks detected in irradiated Chinese Hamster Ovary cells processed for the γ-H2AX assay. Tests results were self-consistent and confirmed that the system serves its dosimetric purpose.

Estimation of the spatial energy deposition in CA1 pyramidal neurons under exposure to 12C and 56Fe ion beams

The exposure to heavy charged particles represents a significant risk to the central nervous system. In experiments with rodents, the irradiation with heavy ions induces a prolonged deficit in hippocampus-dependent learning and memory. The exact nature of these violations remains mostly unclear. In this regard, the estimation of radiation effects at the level of single neurons is of our special interest. The present study demonstrates the results of comparative calculations that are performed to clarify the early physical events in single neurons under the exposure to accelerated 12C and 56Fe ions with different parameters. Using the Geant4-based Monte Carlo simulations, the radiation effects are considered in terms of energy and dose deposition. The spatial patterns of energy and dose depositions within a single neural cell are produced. As additional characteristics, the spectra of the specific energy and energy imparted are estimated. Our results show that the cell morphology is an important factor determining the accumulation of radiation dose in neurons under the exposure to heavy ions. The data obtained suggest a possibility of radiation damage to synapses that are considered to play an important role in radiation-induced violations of hippocampus-dependent learning and memory.

Measurements of 12 C ion fragmentation on thin carbon target from the FIRST collaboration at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI laboratory took data in summer 2011, studying the collisions of a 12C ion beam with Carbon and Au thin targets. The experiment main purpose is the double differential cross section measurement of the carbon ion fragmentation at energies that are relevant both for tumor therapy and space radiation protection applications (100-1000 MeV/u). The FIRST dataset contains carbon ions collisions on a 3.43 g·Cin−2 carbon target (about 24 M events) and on a 0.96 g·cm−2 Au target (about 4.5 M events). The SIS (heavy ion synchrotron) was used to accelerate the 12C ions at the energy of 400 MeV/u. The preliminary results of differential cross sections measurements as a function of angle and energy for carbon target, in the small angle region (θ ≤ 5°), are presented.

Mutagenic effects of heavy-ion beam irradiation on in vitro nodal segments of Artemisia annua L.

Artemisia annua L. is a commercial source of artemisinin. Nevertheless, artemisinin content within the plant is relatively low and varies depending on genotype and environment. To broaden the genetic variability, the mutation effect of 12C-ion beam irradiation on A. annua was examined. Irradiation at 2.5 Gy had a slight lethal effect to nodal segments while a noticeable lethal effect was observed at 5 and 10 Gy. Furthermore, at higher doses (20 and 50 Gy), a severe lethal effect was observed. Mutations at the DNA level of axillary bud-derived shoots were performed by RAPD. The mutation frequency at 10 Gy was about 1.7 and 2.1 times higher than that at 2.5 and 5 Gy, respectively. After growth and artemisinin production observation of 72 irradiated mutants, around 14 and 7 % of them showed higher artemisinin content and artemisinin yield compared to the controls, respectively. The highest artemisinin content in a mutant was 1.43 % DW, which was 3.2-fold higher than the original wild type. Additionally, the highest artemisinin yield in mutants was 3.68 mg/plant, which was around 1.4-fold higher than in the wild type. Moreover, irradiated mutants exhibited antibacterial activity against S. aureus, but the wild types did not. This study presents an effective application of heavy ion beam irradiation to create variations and improve artemisinin production in A. annua.

Effective source size, radial, angular and energy spread of therapeutic 11C positron emitter beams produced by 12C fragmentation

The use of positron emitter light ion beams in combination with PET (Positron Emission Tomography) and PET–CT (Computed Tomography) imaging could significantly improve treatment verification and dose delivery imaging during radiation therapy.The present study is dedicated to the analysis of the beam quality in terms of the effective source size, as well as radial, angular and energy spread of the 11C ion beam produced by projectile fragmentation of a primary point monodirectional and monoenergetic 12C ion beam in a dedicated range shifter of different materials. This study was performed combining analytical methods describing the transport of particles in matter and the Monte Carlo code SHIELD-HIT+.A high brilliance and production yield of 11C fragments with a small effective source size and emittance is best achieved with a decelerator made of two media: a first liquid hydrogen section of about 20cm followed by a hydrogen rich section of variable length.The calculated intensity of the produced 11C ion beam ranges from about 5% to 8% of the primary 12C beam intensity depending on the exit energy and the acceptance of the beam transport system. The angular spread is lower than 1 degree for all the materials studied, but the brilliance of the beam is the highest with the proposed mixed decelerator.

Experimental study of nuclear fragmentation of 200 and 400 MeV/u 12C ions in water for applications in particle therapy

Carbon ion beams in the energy range of about 100–450 MeV/u offer excellent conditions for tumour therapy, in particular for the treatment of deep-seated radio-resistant tumours. Their depth-dose distribution is characterized by a low dose in the entrance channel, small lateral beam spread and an elevated biological effectiveness in the Bragg peak region. In comparison to protons the radiation field of heavier ions stopping in tissue is however more complex due to nuclear fragmentation reactions occurring along their stopping path. This results in an attenuation of the primary beam flux and a build-up of lower-Z fragments with longer ranges causing the characteristic dose tail beyond the Bragg peak. In the present work the characteristics of secondary charged particles at various depths of water were investigated experimentally using 12C ion beams of 200 and 400 MeV/u delivered by the heavy-ion synchrotron SIS-18 at GSI Darmstadt. The nuclear charge Zf of secondary fragments was identified by combining energy loss and time-of-flight (TOF) measurements. Energy spectra and yields were recorded at lab angles of 0° – 10° and at seven different water depths corresponding to the entrance channel, the Bragg peak region and the tail of the Bragg curve.

SU‐E‐T‐502: In Search of the Optimum Ion for Radiotherapy

Purpose: To investigate the physical and biological properties and the clinical potential of several different ions through computer simulations. Methods: Using the Geant4 Monte Carlo toolkit, we calculated spatial dose and LET distributions in a water phantom for monoenergetic beams for four candidate ions with the same range (28 cm in water): 207 MeV/u protons, 244 MeV/u 3He ions, 206 MeV/u 4He ions, and 400 MeV/u 12C ions. An ideal broad beam of 6 cm in diameter was used in the simulations. The scoring voxel volume was set to 1 cubic millimeter. We also recorded the dose contributions from several major nuclear fragments. Furthermore, data for a 5‐cm RBE‐weighted dose SOBP for 12C ions with a range of 30 cm were analyzed. Results: Simulation results showed advantages and disadvantages of each ion. For instance, a 12C ion beam produces the sharpest and narrowest Bragg peak, and the smallest penumbra, but it has the highest entrance to peak dose ratio, and highest and longest nuclear fragmentation tail. Furthermore, the lateral dose halo effect of 12C is substantially greater than other ions. For the same range in water, 3He and 4He ions show very similar features. They have smaller lateral penumbrae than protons, and much smaller fragmentation tails compared with 12C ions. Although protons have the largest lateral penumbra and widest Bragg peak, they do not have an observable fragmentation tail. For a pristine beam of 400 MeV/u 12C ions, the fragmentation tail dose is 15% of the peak dose. In the case of 5‐cm SOBP with 30‐cm range of 12C ions, the fragmentation tail dose can be as high as 30% of the maximum dose. Conclusion: Each type of ion has special advantages and disadvantages. Further research is needed to consider additional factors such as energy dependence, cost effectiveness and RBE. NCI grant P01CA021239

4D particle therapy PET simulation for moving targets irradiated with scanned ion beams

Particle therapy positron emission tomography (PT-PET) allows for an in vivo and in situ verification of applied dose distributions in ion beam therapy. Since the dose distribution cannot be extracted directly from the β+-activity distribution gained from the PET scan the validation is done by means of a comparison between the reconstructed β+-activity distributions from a PT-PET measurement and from a PT-PET simulation. Thus, the simulation software for generating PET data predicted from the treatment planning is an essential part of the dose verification routine. For the dose monitoring of intra-fractionally moving target volumes the PET data simulation needs to be upgraded by using time resolved (4D) algorithms to account correctly for the motion dependent displacement of the positron emitters. Moreover, it has to consider the time dependent relative movement between target volume and scanned beam to simulate the accurate positron emitter distribution generated during irradiation. Such a simulation program is presented which properly proceeds with motion compensated dose delivery by scanned ion beams to intra-fractionally moving targets. By means of a preclinical phantom study it is demonstrated that even the sophisticated motion-mitigated beam delivery technique of range compensated target tracking can be handled correctly by this simulation code. The new program is widely based on the 3D PT-PET simulation program which had been developed at the Helmholtz-Zentrum Dresden-Rossendorf, Germany (HZDR) for application within a pilot project to simulate in-beam PET data for about 440 patients with static tumor entities irradiated at the former treatment facility of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany (GSI). A simulation example for a phantom geometry irradiated with a tracked 12C-ion beam is presented for demonstrating the proper functionality of the program.

Refractive Features and Diffraction Scattering Patterns Observed in the Elastic Scattering of <sup>12</sup>C from <sup>12</sup>C at Various Energies

We have measured the angular distributions for 12C ion beam elastically scattered from 12C target of thickness 17.4 μg/cm2 at energies 15, 18 and 21 MeV which is close to the Coulomb barrier energy for 12C + 12C nuclear system. The elastic scattering of 12C beam on 12C was analysed also at different energies (139.5, 158.8, 180, 240, 288.6, 300, 360 and 420 MeV) from literature in order to obtain the global optical potential parameters, which could fairly reproduce the experimental data. The experimental results were analysed within the framework of both the optical model and the double folding potential obtained with different density-dependent NN interactions which give the corresponding values of the nuclear incompressibility K in the Hartree-Fock calculation of nuclear matter. The agreement between the experimental results and the theoretical predictions in the whole angular range is fairly good.

The Distortion of Energy Deposit Distribution of 12C Ions in Water

The transport process of 12C ions in water was studied with SRIM code and Geant4 toolkit. The SRIM results indicate that the transverse diffusion of 12C ion beam causes distortion of energy deposit along the beam direction. The distortion becomes more notable as the transverse diffusion increases. The simulation results of Geant4 indicate that the influence of secondary fragments on energy deposit distribution would be the main factor causing the distortion in higher energy range. In the region adjacent to the beam line where the contribution from 12C ions dominates, the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary fragments exceed that of 12C. Among all the secondary fragments, the contributions of H, He and B ions are mostly notable. It is also found that some positron-emitting secondary fragments could be very useful for position emitting tomography (PET).