Heavy Charged Particles Research Articles

DICE КМОП КНИ-триггер, устойчивый к воздействию тяжелых заряженных частиц для применения в приемных трактах

DICE КМОП КНИ-триггер, устойчивый к воздействию тяжелых заряженных частиц для применения в приемных трактах

TDDFT-Based Study on the Proton-DNA Collision.

The interaction of heavy charged particles with DNA is of interest for hadrontherapy and the aerospace industry. Here, a time-dependent density functional theory study on the interaction of a 4 keV proton with an isolated DNA base pair (bp) was carried out. Ehrenfest dynamics was used to study the evolution of the system up to about 193 fs. It was observed that the dissociation of the target occurs between 80 and 100 fs. The effect of bp linking to the DNA double helix was emulated by fixing the four O3' atoms responsible for the attachment. The bp tends to dissociate into its main components, namely, the phosphate groups, sugars, and nitrogenous bases. A central impact with an energy transfer of 17.9 eV only produces a base damage while keeping the backbone intact. An impact on a phosphate group with an energy transfer of about 60 eV leads to a backbone break at that site together with a base damage, and the opposite backbone site integrity is kept. As the whole system is perturbed during this collision, no atom remains passive. These results suggest that base damage accompanies all backbone breaks as the hydrogen bonds that keep bases together are much weaker that those between the other components of the DNA.

Simulated space radiation-induced mutants in the mouse kidney display widespread genomic change.

Exposure to a small number of high-energy heavy charged particles (HZE ions), as found in the deep space environment, could significantly affect astronaut health following prolonged periods of space travel if these ions induce mutations and related cancers. In this study, we used an in vivo mutagenesis assay to define the mutagenic effects of accelerated 56Fe ions (1 GeV/amu, 151 keV/μm) in the mouse kidney epithelium exposed to doses ranging from 0.25 to 2.0 Gy. These doses represent fluences ranging from 1 to 8 particle traversals per cell nucleus. The Aprt locus, located on chromosome 8, was used to select induced and spontaneous mutants. To fully define the mutagenic effects, we used multiple endpoints including mutant frequencies, mutation spectrum for chromosome 8, translocations involving chromosome 8, and mutations affecting non-selected chromosomes. The results demonstrate mutagenic effects that often affect multiple chromosomes for all Fe ion doses tested. For comparison with the most abundant sparsely ionizing particle found in space, we also examined the mutagenic effects of high-energy protons (1 GeV, 0.24 keV/μm) at 0.5 and 1.0 Gy. Similar doses of protons were not as mutagenic as Fe ions for many assays, though genomic effects were detected in Aprt mutants at these doses. Considered as a whole, the data demonstrate that Fe ions are highly mutagenic at the low doses and fluences of relevance to human spaceflight, and that cells with considerable genomic mutations are readily induced by these exposures and persist in the kidney epithelium. The level of genomic change produced by low fluence exposure to heavy ions is reminiscent of the extensive rearrangements seen in tumor genomes suggesting a potential initiation step in radiation carcinogenesis.

Diffusion model of the ionization response of LSI elements under exposure to heavy charged particles

An analytical model to evaluate the ionization response of a group of closely located p-n junctions under exposure to a separate heavy charged particle (HCP) in a diffusive approximation is proposed. It is revealed that, taking into account, the inhomogeneous boundary conditions leads to larger values of the collected charge in a separate sensitive area than in estimations in a classical approximation in the case of homogeneous boundary conditions. It is shown that in modern submicron VLSIs it is possible to increase the collected charge through the amplification properties of a parasitic bipolar transistor.

High purity 100 GeV electron identification with synchrotron radiation

In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV π− beam is used to test the method in the NA64 experiment resulting in a suppression factor of 10−5 while the efficiency for electron detection is ∼95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved.

Coulomb effects in high-energy e+e− electroproduction by a heavy charged particles in an atomic field

The cross section of high-energy e+e− pair production by a heavy charged particle in the atomic field is investigated in detail. We take into account the interaction with the atomic field of e+e− pair and a heavy particle as well. The calculation is performed exactly in the parameters of the atomic field. It is shown that, in contrast to the commonly accepted point of view, the cross section differential with respect to the final momentum of a heavy particle is strongly affected by the interaction of a heavy particle with the atomic field. However, the cross section integrated over the final momentum of a heavy particle is independent of this interaction.

Simulation of impact of the HCP on the CNT-nanosensor by the molecular dynamics method

The impact of heavy charged particles (HCPs) on a carbon nanotube (CNT)-nanostructure was simulated by the molecular dynamics method. The results point to the high sensitivity of nanoscale sensors to the local effects caused by the impact of HCPs.

Trilinear-augmented gaugino mediation

We consider a gaugino-mediated supersymmetry breaking scenario where in addition to the gauginos the Higgs fields couple directly to the field that breaks supersymmetry. This yields non-vanishing trilinear scalar couplings in general, which can lead to large mixing in the stop sector providing a sufficiently large Higgs mass. Using the most recent release of FeynHiggs, we show the implications on the parameter space. Assuming a gravitino LSP, we find allowed points with a neutralino, sneutrino or stau NLSP. We test these points against the results of Run 1 of the LHC, considering in particular searches for heavy stable charged particles.

Contribution of caspase-independent pathway to apoptosis in malignant glioma induced by carbon ion beams.

High linear energy transfer (LET) carbon ion beam (CIB) is becoming the best tool for external radiotherapy of inoperable tumors because of its greater cell killing than conventional low LET gamma or X-rays. In the present study, whether the caspase-independent pathway exerts the important contribution in CIB-induced cell apoptosis was explored. Herein we showed, despite the absence of caspase activity using a pan caspase inhibitor Z-VAD-FMK, that apoptosis induced by high LET CIB were clearly observed in the glioma cells. Simultaneously, the increased 8-OHdG level, PARP-1 activity and AIF translocation occurred in response to CIB irradiation. Moreover, it was distinctly higher in the nuclear translocation frequency along with PARP-1 activation when the caspase protease cascade was suppressed in the irradiated glioma cells. Nuclear colocalization between PARP-1 and AIF as well as a positive association of the PARP-1 mRNA expression with AIF translocation frequency indicated that PARP-1 activation controlled the translocation of AIF to the nucleus. Our findings strongly demonstrated that caspase-independent cell apoptosis provided a prominent compensation in the glioma cell death involving the PARP-1/AIF signaling pathway at 24h after CIB exposure, and likely triggered by oxidative damage to DNA. The knowledge on the molecular mechanism of AIF-mediated cell death may be very useful for the improvement of the therapeutic efficacy of malignant gliomas with heavy charged particles.

Assessment of microscopic ion beam field variation using fluorescent nuclear track detectors

Fluorescent Nuclear Track Detectors (FNTDs) feature superior, submicron spatial resolution that allows for single particle track detection. However, when assessing particle fluence from measured track positions, discrimination of actual fluence patterns from stochastic fluctuations due to spatial randomness in particle arrival can only be done at considerably lower resolution. This work quantifies the spatial limits of fluence-based dosimetry of (heavy) charged particles and presents the tools to detect deviations from homogenous fluence in measured data. It is found that deviations in fluence (and hence dose) on a percent level cannot be detected in a carbon beam on scales smaller than several tenths of a millimeter even when using dose levels of 1 Gy. For typical fluences measured with FNTDs, read-out area side-lengths should be larger than 0.2 mm to detect fluence differences of less than 5%.

Effective suppression of pulse shortening in a relativistic backward wave oscillator

This paper discusses pulse shortening present in a C-band relativistic backward wave oscillator (RBWO). Effects of the collector plasma are believed to be the main cause. This viewpoint is first verified in numerical simulation. The simulation results show that light charged particles such as hydrogen ions in the collector plasma would axially enter into the beam-microwave interaction region and suppress high-power microwave (HPM) generation. Simultaneously, heavy charged particles such as oxygen or ferric ions in the collector plasma would radially expand out and change the end reflection of the RBWO. All these effects can result in pulse shortening. Simulations also demonstrate that a coaxial collector can effectively suppress plasma effects by retarding their axial and radial expansions. Furthermore, a HPM experiment has confirmed the validity of the coaxial collector. Using this structure, the output power of the RBWO has been increased from 2.5 GW to 3 GW. No pulse shortening has been observed in the HPM experiment.

Investigation of radiological properties of some shielding materials on charged and uncharged radiation interaction for neutron generator

ABSTRACTRadiation interaction parameters such as total stopping power, projected range (longitudinal and lateral) straggling, mass attenuation coefficient, effective atomic number (Zeff) and electron density (Neff) of some shielding materials were investigated for photon and heavy charged particle interactions. The ranges, stragglings and mass attenuation coefficients were calculated for the high-density polyethylene(HDPE), borated polyethylene (BPE), brick (common silica), concrete (regular), wood, water, stainless steel (304), aluminum (alloy 6061-O), lead and bismuth using SRIM Monte Carlo software and WinXCom program. In addition, effective atomic numbers (Zeff) and electron densities (Neff) of HDPE, BPE, brick (common silica), concrete (regular), wood, water, stainless steel (304) and aluminum (alloy 6061-O) were calculated in the energy region 10 keV–100 MeV using mass stopping powers and mass attenuation coefficients. Two different methods namely direct and interpolation procedures were used to calculate Zeff for comparison and significant differences were determined between the methods. Variations of the ranges, longitudinal and lateral stragglings of water, concrete and stainless steel (304) were compared with each other in the continuous kinetic energy region and discussed with respect to their Zeffs. Moreover, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) of the materials were determined for gamma rays as well and were compared with each other for different photon energies and different mfps in the photon energy region 0.015–15 MeV.

Fluorescent nuclear track images of Ag-activated phosphate glass irradiated with photons and heavy charged particles

In this paper we report about the demonstration of the nuclear track imaging capabilities of Ag-activated phosphate glass. A 375nm laser and confocal laser scanning microscopy (CLSM) were respectively used for track excitation and detection. Specifically, the blue and orange radiophotoluminescent (RPL) tracks and dose distributions observed after irradiation with soft X-rays, gamma rays and heavy charged particles (HCPs) are examined. In addition, the origins of the reductions in RPL efficiency for high-dose X-ray irradiation and for irradiation with HCPs with high linear energy transfer (LET) values are investigated via a CLSM and a conventional fluorescent reader and discussed.

Energy losses of positive and negative charged particles in electron gas

A heavy charged particle propagation through electron gas has been studied using combination of non-relativistic quantum mechanics and the Green’s functions method. The energy loss of a charged particle has been found in the case of large transferred momentum taking into account the interference term in the expression for the rate. The dependence of the energy loss of a charged particles in electron gas with nonzero temperature on the sign of the charge has been obtained.

The influence of the dose assessment method on the LET dependence of the relative luminescence efficiency of LiF:Mg,Ti and LiF:Mg,Cu,P

Thermoluminescent detectors (TLDs) are solid state detectors commonly used for dose monitoring and dose mapping in many earth and space applications. Among all the crystals available, the ones based on lithium fluoride (LiF) are the most widely spread and studied around the world. In the last years the use of these TLDs in complex heavy charged particles (HCPs) fields, as in spacecraft or in radiotherapy beams, has grown rapidly leading to the necessity of an accurate characterization of the detectors’ response in these radiation environments.In this work, 6LiF:Mg,Ti, 7LiF:Mg,Ti, 6LiF:Mg,Cu,P and 7LiF:Mg,Cu,P detectors were exposed to different radiation qualities in order to investigate the dependence of their relative luminescence efficiency on the linear energy transfer (LET) of the incident particles. The measured efficiencies were in good agreement with literature.In relation to this issue, different dose assessment methods, i.e. peak height, signal integration over different regions of interest (ROIs) and glow curve deconvolution, were compared and their influence on the measured relative luminescence efficiency values was assessed. For both LiF:Mg,Ti and LiF:Mg,Cu,P detectors, no relevant differences were found in the relative luminescence efficiency evaluated by means of main peak height, main peak ROI and main peak deconvolution. On the other hand, if the integration of the signal is extended to the high temperature zone (248–310 °C) of LiF:Mg,Ti or the low temperature zone (125–185 °C) of LiF:Mg,Cu,P, significant deviations were found.

Investigation of the diamond based detectors characteristics with different thickness of the sensor element

This work is devoted to study of the diamond based radiation detectors. Experiments were carried out with two types of detectors: based on a thin diamond film and on a composite diamond plate. The following types of ionizing radiation has been used in experiments: beta radiation of 90Sr - 90Y, fission fragments and alpha particles of 252Cf, and Kr ions obtained at the particle accelerator. It is shown that the developed thin-film diamond based detector effectively registers heavy charged particles, whereas beta, neutron and gamma radiation does not give a significant contribution to the detector signals. Those type of detectors are proposed for measurement of heavy charged particles linear energy transfer in diamond. The multilayer diamond based detector (detector with a composite diamond plate) showed improved charge collection efficiency values in compare with the detection with a single diamond plate.

The Evolving Role of Particle Radiotherapy in the Treatment of Head and Neck Cancer

Radiotherapy has a proven role in the management of most types of head and neck cancer but results are suboptimal in certain clinical situations. Particle radiotherapy offers the opportunity to improve outcomes in such cases. Fast neutron radiotherapy is a high linear energy type of radiotherapy and may be advantageous for many “radioresistant” tumors such as salivary gland malignancies, mucosal melanomas, and sarcomas. Proton radiotherapy offers greatly improved dose distributions compared to conventional photon radiation and this allows for higher radiation doses and potentially improved outcomes for tumors near critical structures such as the brain stem and optic structures and in the re-irradiation setting. The applicability of proton radiotherapy in other settings is also discussed. Heavier charged particles, such as carbon ions, offer both improved radiation dose distributions and the radiobiological advantage of fast neutron radiotherapy. While data is limited, it appears that carbon ions are advantageous in the same subset of tumors as fast neutron radiotherapy, but the improved dose distribution theoretically should result in reduced morbidity. Boron neutron capture therapy (BNCT) is a technique that has recently been used to treat recurrent head and neck tumors and new boron carrier compounds are being developed for this application. Clinical data on the use of each of these modalities in the treatment of head and neck cancer is reviewed and their current role in the treatment of head and neck cancer is summarizedKey Words: Neutron radiotherapy, proton radiotherapy, carbon ion radiotherapy, BNCT

Design and Simulation of Novel Gated Integrator for the Heavy ion Beam Monitors System

In this study, the objective is to realize a Gated Integrator (GI) circuit for silicon strip, Si(Li), CdZnTe and CsI detectors etc. With the development of radioactive ion beam physics, heavy-charged particles like carbon ions have been applied to the treatment of deep-seated inoperable tumors in the therapy terminal of the Heavy ion Research Facility in Lanzhou (HIRFL) located at the Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS). A high resolution current measurement circuit was developed to monitor the beam current at 1pA range. The circuit consisted of a low current high sensitivity I/V converter and gated integrator in an energy spectroscopy. A low offset voltage precision amplifier and new guarding and shielding techniques were used in the I/V converter circuit which allowed to measure low current. This paper will show a MOS switch configuration which is used to prevent leakage current and novel technique to compensate a charge injection in the reset switch.

Measuring space radiation shielding effectiveness

Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles is described. Using accelerated alpha particles at the National Aeronautics and Space Administration Space Radiation Laboratory at Brookhaven National Laboratory, the method is applied to sample tiles from the Heat Melt Compactor, which were created by melting material from a simulated astronaut waste stream, consisting of materials such as trash and unconsumed food. The shielding effectiveness calculated from measurements of the Heat Melt Compactor sample tiles is about 10% less than the shielding effectiveness of polyethylene. Shielding material produced from the astronaut waste stream in the form of Heat Melt Compactor tiles is therefore found to be an attractive solution for protection against space radiation.

Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at √{{s}} = 13 TeV using the ATLAS experiment

Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at √{{s}} = 13 TeV using the ATLAS experiment