Bremsstrahlung Energy Research Articles

Photonuclear reactions on 59Co at bremsstrahlung end-point energies of 40–130 MeV* *Supported in part by the Ministry of Science and Higher Education of the Russian Federation (075-15-2021-1360), and by the project of the National Center for Physics and Mathematics (NCPM) No. 6 ''Nuclear and Radiation Physics,'' direction 6.5.1

Relative yields were measured in the 40−130 MeV bremsstrahlung induced reactions of 59Co. The experiments were performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-line γ-ray spectrometric techniques. The bremsstrahlung photon flux was calculated with the Geant4 program. The cross sections were calculated by using the computer code TALYS-1.96 with different models and were found to be in good agreement with the experimental data.

Formation of medical radioisotope 111In in photonuclear reactions

The possibility of photonuclear production of 111In radioisotope has been investigated. The enriched target 112Sn was irradiated at the linear electron accelerator LUE-75 of A. Alikhanian National Science Laboratory (Yerevan, Armenia) at the bremsstrahlung endpoint energy Eγmax = 55 MeV. The cross section per equivalent quantum for reactions 112Sn(γ,x)111In, 112Sn(γ,n)111Sn, 112Sn(γ,2n)110Sn, 112Sn(γ,3n)109Sn,112 Sn(γ,pn)110mIn, 112Sn(γ,pn)110g110In, 112Sn(γ,p2n)109In have been measured via the method of activation and off-line γ-ray spectrometric technique. The cross section per equivalent quantum of the 111In in photonuclear reaction was compared with its cross section in proton induced reaction on cadmium targets and other possible 111In production routes. It is shown that the photonuclear method can be used for the production of 111In.

CROSS-SECTIONS OF PHOTONEUTRON REACTION natMo(γ,xn)93mMo AT THE BREMSSTRAHLUNG ENERGY UP TO 95 MeV

The photoproduction of the 93mMo nucleus on natural molybdenum was studied using the electron beam of the LUE-40 linac RDC “Accelerator” NSC KIPT. Measurements were performed using the activation method and off-line γ-ray spectrometric technique. For the natMo(γ,xn)93mMo reaction the experimental flux-averaged cross-sectionϭ(Eγmax)m at the bremsstrahlung end-point energy range of 38…93 MeV was first time determined. The theoretical values of the yields Ym,g(Eγmax) and flux-averaged cross-sections(Eγmax)m,g for the natMo(γ,xn)93m,gMo reactions were calculated using the cross-sections ϭ(Eγ) from the TALYS1.96 code for different gamma strength functions and level density models. The comparison showed strong discrepancies between the experimental values and the theoretical results of (Eγmax)m.

Measurement of effective 98Mo(n,γ)99 Mo reaction cross-section in the epi-cadmium neutron flux produced by 10 MeV electron LINAC with Ta-BeO assembly

An experiment was carried out to study the feasibility of 99Mo production using an electron accelerator based epi-cadmium neutron source. The neutrons were produced by the interaction of bremsstrahlung end-point energy of 10 MeV with BeO blocks and the neutrons thus produced were moderated using High Density Polyethylene blocks. Effective cross-section of 98Mo(n,γ)99Mo reaction was measured using foil activation method. An enhancement in the effective cross-section due to resonances in the epi-cadmium region was observed. The photons and neutron production/transport in the experimental set-up were simulated using the FLUKA Monte Carlo code. The simulations were found to be in good agreement with the experimental findings.

Angular Distribution of Bremsstrahlung Spectral Temperature Measured in a Full Dimension of ECR Ion Source Using NaI(TI) Detector

Measurement of angular distribution (AD) of the bremsstrahlung spectral temperature from a full dimension of the Electron Cyclotron Resonance Ion Source (ECRIS) along the beam axis is challenging. To overcome some challenges, this paper presents the AD of the bremsstrahlung spectral temperature measured in a full dimension of the ECRIS along the beam axis using data obtained from the Busan Center of Korea Basic Science Institute (KBSI). The bremsstrahlung spectral temperature from 28-GHz ECR Ion source at the KBSI was measured in six, three, and nine azimuthal angles at the injection, centre, and extraction sides of the ECRIS using three round type thallium-activated sodium iodide (NaI(TI)) scintillation detectors. Monte Carlo simulation based on the Geant4 software package was performed to take the geometrical acceptance and energy-dependent detection efficiency into account due to large non-uniformity in the material budget. True bremsstrahlung energy spectra from the 28-GHz ECR ion source were obtained using the inverse-matrix deconvolution method. The unfolding method was based on a full geometry of the Geant4 model of the ECRIS plasma. The results show that in all three measurement locations, the highest value of the spectral temperature was at an angle of 30∘ coincident with one of the maximum angles of the ECRIS plasma shape.

Proton-boron fusion scheme taking into account the effects of target degeneracy

The proton-boron (p-B11) reaction is regarded as the holy grail of advanced fusion fuels, since the primary reaction produces three α particles with few neutrons and induced radioactivities from second order reactions. Compared to the deuterium-tritium reaction a much higher reaction temperature is required. Moreover, bremsstrahlung energy losses due to the high nuclear charge of boron deem it seemingly apparent than a fusion reactor based on deuterium-tritium plasma in equilibrium is to say the least very difficult. It is becoming more appealing to collide intense laser beams or accelerated proton beams with a boron target to produce p-B11 reactions. The fusion yield of p-B11 reactions is closely related to proton beam parameters and boron target conditions such as density, temperature, and ingredients. Degeneracy will increase fusion yields by reducing the stopping power of injected protons. In this work, we suggest a scheme for beam-target p-B11 fusions via injecting a MeV proton beam into a highly compressed quantum degenerated boron target. Such a boron target can be achieved via quasi-isentropic compression of solid boron by using precisely shaped laser pulses. Our results indicate that for densities ranging from 103 to 104ρs, where ρs is the density of solid boron, contributions of bound and free electrons to the stopping of protons can be completely disregarded and dramatically reduced, respectively. The result is an increase in fusion yield by orders of magnitude. Furthermore, in order to achieve multiplication factor F greater than one, with F defined as the ratio of output fusion energy to the energy of injected protons, it is found there exists a minimum possible density of boron target, which is 1.8×105ρs when the kinetic energy of injected protons is 880 keV. Published by the American Physical Society 2024

Research on natAg(γ,xn)103-106Ag reaction cross sections with the bremsstrahlung end-point energy of 70 and 75 MeV

The flux-weighted average cross sections of natAg(γ,xn)103-106Ag reactions were measured with the bremsstrahlung end-point energy of 70 and 75 MeV using an activation and off-line γ-ray spectrometric technique. The GEANT4 code was used for the simulation of the bremsstrahlung spectra. The cross sections of natAg(γ,xn) 103-106Ag reactions as a function of mono-energetic photons were theoretically calculated by using the TALYS-1.96 code. The data of the present work and literature at different bremsstrahlung end-point energy are found to be in agreement with the theoretical values within the uncertainty limit. It can be seen that the flux-weighted average cross sections of the natAg(γ,xn)105.106Ag reactions increase with bremsstrahlung energy up to the Giant Dipole Resonance region. Thereafter, a small decrease trend with the bremsstrahlung energy was seen due to the opening of another reaction channel.

Measurement of the flux-weighted average cross section for the \(^{186}\)W\((\gamma,p)^{185}\)Ta reaction at the bremsstrahlung end-point energy of 70 MeV

Abstract. The flux-weighted average cross section for the 186W(γ,p)185Ta reaction induced with 70 MeV bremsstrahlung end-point energy was measured using the activation method in combination with off-line gamma activity measurement. The 27Al(γ,2pn)24Na monitor reaction was used for the determination of the bremsstrahlung flux. The bremsstrahlung photons used to produce the photonuclear reactions were generated from a thin tungsten (W) converter by bombardment with a 70 MeV electron beam. The experimental flux-weighted average cross section is compared with the theoretical prediction, for which the absolute cross section was calculated using the TALYS 1.95 code and the bremsstrahlung spectrum was simulated using the computer program MCNPX. The present experiment was carried out at the 100 MeV electron linac of the Pohang Accelerator Laboratory, POSTECH, Pohang, Korea.

STUDY THE ISOMERIC RATIOS IN PHOTONUCLEAR EXPERIMENTS ON THE LUE-40 LINAC RDC “ACCELERATOR” NSC KIPT

The results of photoproduction of isomeric pairs from the (γ,xn) and (γ,pxn) reactions on nuclei from Zr up to Ta at the bremsstrahlung end-point energy range 30…100 MeV are systematized. Measurements were performed at the electron beam of the LUE-40 linac RDC “Accelerator” NSC KIPT using the activation method and off-line γ-ray spectrometric technique. The theoretical isomeric ratios IR for the nuclei-products of studied reactions were calculated using the cross-sections σ(E) from the TALYS1.95 code for six different level density models. The data from the international databases were additionally used to compare experimental results and theoretical predictions. The obtained results let us make conclusions about trends of values and energy dependence of IR in studied photonuclear reactions. Further directions of experimental research in the RDC “Accelerator” NSC KIPT are discussed.

Experimental observation of excitation and deexcitation of an as-yet unknown isomer during the irradiation of the 178m2Hf isomer by low energy bremsstrahlung photons

The whole set of spectra accumulated during the 178m2Hf isomer triggering experiments in 2015 has been analyzed in detail. It looks like an as-yet unknown isomer of 178Hf is excited during irradiations. The half-life of this isomer could to be between one and five days. As a result, the efficiency of triggering, which was recorded in 2015, appears to be underestimated at least by a factor of two. Additionally, the obtained results allow suggesting why other experimental groups failed to confirm the possibility of 178m2Hf isomer triggering.

Photonuclear reactions on stable isotopes of selenium at bremsstrahlung end-point energies of 10−23 MeV

In this study, experiments were performed at bremsstrahlung end-point energies of 10−23 MeV with the beam from the MT-25 microtron using the γ-activation technique. The experimental values of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions. Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 10 to 23 MeV. Therefore, taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.

Production of 180m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{180\ extrm{m}}}$$\\end{document}Hf in photoproton reaction 181\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}}$$\\end{document}Ta(γ,p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\gamma ,p)$$\\end{document} at energy Eγmax=35\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_{\\mathrm{\\gamma max}} = 35$$\\end{document}–95 MeV

The production of the 180mHf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{180\ extrm{m}}\ extrm{Hf}$$\\end{document} nuclei in the photoproton reaction 181Ta(γ,p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)$$\\end{document} was studied at end-point bremsstrahlung energies Eγmax=35\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_{\\mathrm{\\gamma max}}=35$$\\end{document}–95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document} activation and off-line γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections ⟨σ(Eγmax)⟩m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle {\\sigma (E_{\\mathrm{\\gamma max}})}\\rangle _{\ extrm{m}}$$\\end{document} for the 181Ta(γ,p)180mHf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)^{180\ extrm{m}}\ extrm{Hf}$$\\end{document} reaction were determined, and at Eγmax>55\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_{\\mathrm{\\gamma max}} > 55$$\\end{document} MeV obtained for the first time. The measured values, as well as the literature data, significantly (by more that an order of magnitude) exceed the theoretical flux-averaged cross-sections ⟨σ(Eγmax)⟩th\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle {\\sigma (E_{\\mathrm{\\gamma max}})}\\rangle _{\ extrm{th}}$$\\end{document}. The ⟨σ(Eγmax)⟩th\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle {\\sigma (E_{\\mathrm{\\gamma max}})}\\rangle _{\ extrm{th}}$$\\end{document} values were calculated using the cross-section σ(E)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma (E)$$\\end{document} computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections from the TALYS computation for the reactions 181Ta(γ,p)180Hf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)^{180}\ extrm{Hf}$$\\end{document} and 181Ta(γ,n)180Ta\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,n)^{180}\ extrm{Ta}$$\\end{document} was performed. It was shown that the photoproton (γ,p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\gamma ,p)$$\\end{document} to photoneutron (γ,n)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\gamma ,n)$$\\end{document} strength ratio is consistent with the estimates based on the isospin selection rules and the value from the (e,e′p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(e,e'p)$$\\end{document} experiment.

Investigation of (γ, xpxn)-reactions on titanium, lutetium, nickel and chromium nuclei at Ebr=37 MeV

For the first time, both the flux-weighted average yields of the 50Cr(γ,pn+2n)48V, natTi(γ,pxn)46Sc, 48Ti(γ,p)47Sc reactions and the isomeric yield ratios of the 175Lu(γ,n)174Lum,g reaction were measured at a bremsstrahlung end-point energy of 37 MeV. The flux-weighted average yields of the 52Сr(γ,n)51Cr, 58Ni(γ,n)57Ni and 58Ni(γ,p)57Co reactions were also measured and their values coincided with the results of the works of the other authors. According to the results of modeling within the framework of the TALYS-1.96 code, a significant contribution of non-statistical processes is ascertained to the mechanisms of the 48Ti(γ,p)47Sc and 50Cr(γ,pn+2n)48V reactions.

Determination of the bremsstrahlung spectra by unfolding technique based on [formula omitted]Bi([formula omitted], xn) reactions

This work explores and describes the possibility of assessment of high energy bremsstrahlung spectrum, through the use of photonuclear reactions. Experimentally obtained values of saturation activities of various Bi isotopes, created by 209Bi(γ, xn) reactions in the 100 MeV bremsstrahlung beam were used in calculations. The photon spectrum is obtained by utilizing the unfolding techniques and cross sections data calculated by the TALYS 1.96 code. The experimental results were compared with the results obtained by Geant4 Monte Carlo simulation.

Comparison of End-Point Energies of Bremsstrahlung Photons from 28- GHz ECR Ion Source in Three Measurement Locations

Bremsstrahlung photons measurement show elevated energy emission beyond critical energy in 28-GHz ECR and its nature is not revealed. Thus, the aim of this study is to unveil the nature of high end-point energies at the three measurement locations. Bremsstrahlung photons from a 28-GHz ECR ion source were measured at Busan center of Korean Basic Science Institute (KBSI). The gamma-ray detection system consists of three round type NaI(Tl) scintillation detectors placed 62 cm radially from the beam axis at the three measurement locations namely injection, centre and extraction sides of an ECR ion source, and a NaI(Tl) scintillation detector placed at the view port for monitoring photon intensity along the beam axis. Such design of the experiment was based on the inner structure of the ECR ion source and the shape of the ECR plasma. Also, bremsstrahlung photons were measured by exchanging the detector positions for studying systematic uncertainties. Monte Carlo simulation based on the Geant4 package was performed to take geometrical acceptance and the energydependent detection efficiency into account due to large non-uniformity in the material budget. True bremsstrahlung energy spectra from the 28-GHz ECR ion source were extracted using an inverse matrix unfolding method. The measured high end-point energies at the three measurement locations were 1.68 MeV, 1.72 MeV and 2.04 MeV for the injection, centre and extraction sides, respectively. The high end-point energy values of the measured bremsstrahlung photons beyond the theoretical energy value of 1.33 MeV were found to be correlated with the structure of the ECR ion source and the shape of the ECR plasma. Furthermore, the high end-point energy values resulting from the bremsstrahlung photons measurements in the 28-GHz ECR plasma are due to the higher number of unconfined electrons arriving at the chamber wall easily, and producing higher bremsstrahlung photons. The unconfined electrons are the results of imperfect magnetic confinement that cause electrons to escape from the plasma volume.

Isomeric pair 95 m,g Nb in the photonuclear reactions on natMo at the bremsstrahlung end-point energy of 38–93 MeV

The photonuclear reaction was studied using the electron beam from the NSC KIPT linear accelerator LUE-40. The experiment was performed using the activation and off-line γ-ray spectrometric technique. The experimental isomeric yield ratio (IR) was determined for the reaction products at the bremsstrahlung end-point energy range of 38–93 MeV. The obtained values of IR are in satisfactory agreement with the results of other studies and extend the range of previously known data. The theoretical values of the yields and the IR for the isomeric pair from the reaction were calculated using the partial cross-sections from the TALYS1.95 code for six different level density models. For the investigated range of , the theoretical dependence of IR on energy was confirmed – the IR smoothly increases with increasing energy. The comparison showed a noticeable difference (more than 3.85 times) in the experimental IR relative to all theoretical estimates.

Multiparticle natSe([formula omitted]) reactions induced with bremsstrahlung end-point energies of 20–80 MeV

The flux weighted average cross sections 〈σ〉 and cross sections per equivalent photon σq were first measured for the photonuclear multiparticle reactions natSe(γ, xnyp) at end-point bremsstrahlung gamma energies ranging from 20 to 80 MeV. The experiments were performed with the beam from the electron linear accelerator LINAC-200 with the use of the γ-activation technique. The bremsstrahlung photon flux was calculated with the program Geant4. The theoretical values of the flux weighted average cross sections 〈σ〉 and the cross sections per equivalent photon σq were calculated using the partial cross section σ(E) computed with the TALYS package code and the combined model of photonuclear reactions.

STRUCTURE OF MASS DISTRIBUTIONS OF PHOTOFISSION PRODUCT YIELDS OF 238U AT 17.5 MeV BREMSSTRAHLUNG ENERGY

The values of 29 relative yields of products belonging to 26 mass chains of photofission of 238U were obtained at a maximum bremsstrahlung energy of 17.5 MeV (near the second chance fission threshold). The stimulation of the 238U photofission reaction was performed at the electron accelerator of the Institute of Electron Physics of the National Academy of Sciences of Ukraine, the M-30 microtron. The GEANT4 toolkit was used to model the components of the bremsstrahlung spectrum. The presence of a fine structure in the mass distribution of heavy product yields was found to be localized in the mass range 133-134, 138-139, and 143-144. A multi gaussian model (superposition of three Gaussians) was used to theoretically describe the structure. The calculated values of product yields using the GEF code describe in general terms and predict the fine structure of the mass distribution of photofission products of 238U.

A brief peek at the cyclotron in our microscope

The influence of low energy bremsstrahlung emission on the performance of electron spectrometers and monochromators is investigated. Despite the occurrence of multi-photon events, the effect of the main azimuthal (organ pipe) mode is likely to be negligible. Potentially more serious is a new radial mode not considered in the classical theory but revealed in the quantum mechanics picture. The progress of the finely focused wave at the spectrometer entrance slit is described by a coherent wave packet of many oscillator states. It is shielded from disruption by a relatively much longer half-life. Cavity effects causing additional suppression of bremsstrahlung emission are briefly discussed.

A CsI(Tl) hodoscope on CSHINE for Bremsstrahlung [formula omitted]-rays in heavy ion reactions

Bremsstrahlung γ production in heavy ion reactions at Fermi energies carries important physical information including the nuclear symmetry energy at supra-saturation densities. In order to detect the high energy Bremsstrahlung γ rays, a hodoscope consisting of 15 CsI(Tl) crystals read out by photo multiplier tubes has been built, tested and operated in experiment. The resolution, efficiency and linear response of the units to γ rays have been studied using radioactive source and (p,γ) reactions. The inherent energy resolution of 1.6%+2%/Eγ1/2 is obtained. Reconstruction method has been established through Geant 4 simulations, reproducing the experimental results where comparison can be made. Using the reconstruction method developed, the whole efficiency of the hodoscope is about 2.6×10−4 against the 4π emissions at the target position, exhibiting insignificant dependence on the energy of incident γ rays above 20 MeV. The hodoscope is operated in the experiment of 86Kr+124Sn at 25 MeV/u, and a full γ energy spectrum up to 80 MeV has been obtained.