Energy Loss Of Fission Fragments Research Articles

Penetration of gases by fission fragments—Comparison between selected models and the data

A comparison between a few models of fission fragment penetration in several gases used in fission chambers is presented. To verify the energy loss of fission fragments, a comparison methodology was developed. It is based on comparative analysis of range experiments from third party publications with currently available models. We compared results from the SRIM code, the ICRU parametrization model implemented in Geant-4 and the LSS model. Albeit they are based on different hypotheses about the underlying physics that are not specific to fission fragments, those models reproduce fairly well the trend and order of magnitude of experimental data. Thanks to effective use of semi-empirical correlation fitted over large number of points, the SRIM code gives the closest results to experimental data: thus it is the model of choice for predicting and interpreting fission chambers’ signal.

A New Method for Measuring Specific Energy Losses of Fission Fragments

A method for measuring the specific energy losses of fission fragments is described. It is based on the digital processing of signals from a double Frisch-grid ionization chamber. The energy losses of 252Cf fission fragments were measured for masses and energies varying over wide ranges. A method is proposed for a more correct account of fission-fragment energy losses in the targets and entrance windows of spectrometers.

Energy losses of fission fragments and the density effect in gases with different collision frequencies

Our calculation of the trajectories of the fission fragments in the experiment of [4] showed that the density effect becomes much weaker when the nonlinear relation between the ion charge and the velocity of the fragments during the stopping process is taken into account. The calculation was based on measurements of the energy losses of fission fragments in air, which were performed in the present work, and modern data on energy losses in argon. The error of the experiment described in the present work is close to 10%. It can be asserted to the same degree of accuracy that the density effect does not influence the energy losses in the experimental pressure range from 300 to 8000 Pa.

Charge determination of fission fragments via energy loss and X-ray measurements

Energy loss of fission fragments of specified charges and kinetic energies have been measured with a gas detector telescope. The singles data from the telescope (DE-E R) and coincidence data with a HP Ge X-ray detector (DE-E R-X) were taken using a 252Cf fission source. An empirical expression for the dependence of Z eff on charge and energy of fragments has been determined by fitting the observed energy loss behaviour of the fission fragments. The resolution in the measurement of charge from event by event analysis of DE-E R data for the light fragment mass group was found to be about 1.8 charge units (FWHM). The present data were analysed to determine the fragment charge distribution as well as the X-ray yield per fragment in 252Cf fission.

A nuclear fragment detector for experiments with backscattered laser photons

A new fission fragment detector (FD) was designed and built for the experiments with backscattered laser photons at intermediate energies. The FD is based on low-pressure multiwire proportional chambers to detect the trajectories and energy losses of fission fragments and ( ΔE− E) plastic scintillator modules to measure the energy of light charged particles such as protons, pions, etc. The results of calibrations with a spontaneous fission 252Cf source and first experiments on bremsstrahlung-induced photofission of 238U and 237Np nuclei at ( E γ ) max = 2 GeV are presented.

Response of thin film plastic scintillator to fission fragments

Thin plastic scintillator films of different thicknesses are prepared and their characteristics response to fission fragments from 252Cf is studied. It is observed that the peak to valley ratio of fission fragments depends non-linearly upon the thickness of thin films. This ratio for the heavy fragments is larger than that of the light fragments by a factor of 1.5–1.9 for the whole range of thickness investigated. The laminated structure of the films shows slightly higher gain (≈5 %) but the resolution remains practically the same. The energy loss of fission fragments in plastic scintillator (NE 102A) is measured. A simple system for a “start-detector”, employing such a thin film and a photomultiplier, is also described for the time-of-flight experiments.

A mass-selecting apparatus to measure the energy loss of fission fragments in gases

We describe an apparatus combining solid-state and gas ionization chamber techniques to measure — for both fragments released in a fission event — the energy lost in a given gaseous range and the residual energy. This device allows to measure the energy loss in gases of fission fragments selecting their masses The performances of the apparatus are discussed referring to the data obtained by slowing down fission fragments from 252Cf in gaseous argon.

Measurement of the energy loss in argon of fission fragments having selected masses

The energy losses of fission fragments from 252Cf were measured, selecting their masses, along their range in argon. The results are discussed normalizing the fragment kinetic energies to the same initial value.

On the Energy Loss of Fission Fragments in Composite Systems

Accurate predictions of the energy loss of fission fragments in gaseous and solid stopping media are of considerable interest in a number of fields such as fissio-chemistry and direct energy conver...

Semi-Empirical Approach for Fission Fragment Energy Degradation in any Elementary Medium

A semi-empirical equation for the electronic energy loss of fission fragments has been derived by fitting the theoretical approach of Bohr, specifically developed for heavy stopping materials, to experimental data in gases and solids in a wide range of atomic numbers. The fitting procedure was performed by choosing a different expression for the number of electrons of the medium taking part in the stopping process, which includes empirical parameters obtained by fitting to experiment.The equation enables the energy loss of fission fragments in substances of any Z2, regardless of their physical state, to be predicted to a good degree of accuracy down to energies of approximately 20 MeV.

Degradation of the Time Characteristics of Surface Barrier Detectors with Fission Fragment Dose

Differential energy losses of fission fragments in thin carbon films as function of mass and initial energy mapped by time of flight method

Range-Energy Relation and Energy Loss of Fission Fragments in Solids

The energies of fission fragments transmitted through Al, Ni, Ag, Au, and U-Pd have been measured with surface-barrier detectors. The results, converted to the Lindhard-Scharff-Schiott (LSS) dimensionless parameters $k\ensuremath{\rho}$ (range) and $\ensuremath{\epsilon}$ (energy), were found to fit the empirical equation $k\ensuremath{\rho}=1.158{\ensuremath{\epsilon}}^{\frac{1}{2}}[1\ensuremath{-}\mathrm{exp}(0.0987\ensuremath{\epsilon})]+0.01939\ensuremath{\epsilon}$ in the region $12\ensuremath{\le}\ensuremath{\epsilon}\ensuremath{\le}348$. These results are 10-20% lower than those predicted by the LSS theory. A description is given of the effect of relatively simple modifications to this theory, and suggestions are presented for a more rigorous theoretical approach.

Energy Loss of Fission Fragments in Light Materials

A calibrated silicon detector provided range-energy data for ${\mathrm{Cf}}^{252}$ fission fragments in ${\mathrm{H}}_{2}$, ${\mathrm{D}}_{2}$, ${\mathrm{N}}_{2}$ and Mylar. Bohr's classical stopping-power theory and Lindhard's more recent Thomas-Fermi model both underestimate the measured energy losses. For both theories, the discrepancy with experiment is a monotonic function of the atomic number of the stopping material, at least for the limited range of materials studied.

Density Effect on Energy versus Range of Fission Fragments in Gases

The density effect on specific energy loss of fission fragments in gases is discussed. Previously reported range-versus-energy data for median-mass light and heavy fission fragments in ${\mathrm{H}}_{2}$, He, air, and Ar are corrected for saturation of the density effect.