Helium Production Cross Sections Research Articles

New remarks on KERMA factors and DPA cross section data in ACE files

KERMA factors and DPA cross section data are essential for nuclear heating and material damage estimation in fusion reactor designs. Recently we compared KERMA factors and DPA cross section data in the latest official ACE files of JENDL-4.0, ENDF/B-VII.1, JEFF-3.2 and FENDL-3.0 and it was found out that the KERMA factors and DPA cross section data of a lot of nuclei did not always agree among the nuclear data libraries. We investigated the nuclear data libraries and the nuclear data processing code NJOY and specified new reasons for the discrepancies; (1) incorrect nuclear data and NJOY bugs, (2) huge helium production cross section data, (3) gamma production data format in the nuclear data, (4) no detailed secondary particle data (energy–angular distribution data). These problems should be resolved based on this study.

A reevaluation of radiation damage cross sections

In the past years, INC models simulating spallation reactions have been undergoing considerable development, and their results are more and more scrutinized by experimental work. Recently, IAEA has led an international collaboration to independently benchmark various INC models. The preliminary results of this collaboration indicate that while the Bertini model performs well in predicting neutron production, it greatly lacks the capability to predict light charged particle emission compared to CEM’03 and INCL. This drives us to completely reevaluate the NCSU radiation damage cross section database, which was developed 7years ago using a combination of CEM2k and Bertini models for benchmarking experimental data. The reevaluation currently involves just the CEM’03 model in MCNPX due our limited code access. Our preliminary results are in reasonable agreement with the NCSU database for the helium and hydrogen production cross section, but there are obvious differences for the displacement cross section. Such similarities and differences are being investigated, and the validity of the CEM’03 model for predicting radiation damage to materials is being examined. The reevaluated radiation damage cross sections presented in this paper are used in calculating radiation damage to the target assembly currently running at SNS, and the results are compared with those of previous studies.

Fragmentation ofN14,O16,Ne20, andMg24nuclei at 290 to 1000 MeV/nucleon

We report fragmentation cross sections measured at 0 deg for beams of 14-N, 16-O, 20-Ne, and 24-Mg ions, at energies ranging from 290 MeV/nucleon to 1000 MeV/nucleon. Beams were incident on targets of C, CH2, Al, Cu, Sn, and Pb, with the C and CH2 target data used to obtain hydrogen-target cross sections. Using methods established in earlier work, cross sections obtained with both large-acceptance and small-acceptance detectors are extracted from the data and when necessary corrected for acceptance effects. The large-acceptance data yield cross sections for fragments with charges approximately half of the beam charge and above, with minimal corrections. Cross sections for lighter fragments are obtained from small-acceptance spectra, with more significant, model-dependent corrections that account for the fragment angular distributions. Results for both charge-changing and fragment production cross sections are compared to the predictions of the Los Alamos version of the Quark Gluon String Model (LAQGSM) as well as the NUCFRG2 and PHITS models. For all beams and targets, cross sections for fragments as light as He are compared to the models. Estimates of multiplicity-weighted helium production cross sections are obtained from the data and compared to PHITS and LAQGSM predictions. Summary statistics show that the level of agreement between data and predictions is slightly better for PHITS than for either NUCFRG2 or LAQGSM.

Exclusive measurements on [formula omitted] at 1 A Gev with the SPALADIN setup at GSI

A new type of spallation experiments has been carried out at GSI, Darmstadt (Germany) in order to understand the spallation mechanism in greater details. These experiments use the inverse-kinematics technique where the ion beam is directed onto a liquid Hydrogen target, allowing the detection of heavy spallation residues in coincidence with low center-of-mass energy light particles. The setup is based on A Large Acceptance DIpole magNet (ALADIN) coupled with a multitrack Time Projection Chamber (TPC), a hodoscope and a neutron detector. First, data on 56 Fe + p at 1 A GeV were taken in February 2004. In the on-going analysis, isotopic cross-sections have been determined and compared to data taken at the FRagment Separator in GSI. Mean values and width of residue velocity distributions have also been obtained as well as Helium production cross-section. First, coincidence data are being analyzed.

Production of 4He and 3He from tantalum and tungsten irradiated with nucleons at energies up to 1 GeV

Abstract The comparison of different methods of calculation and computer codes used to obtain helium isotope production cross-sections for nuclear reactions induced by nucleons at energies up to 1 GeV was performed. The cross-sections were calculated using the GNASH code, the modified ALICE code, the DISCA code and the CASCADE/INPE code. The evaluation of the helium production cross-section for tantalum and tungsten was performed using the results of model calculations, available experimental data and systematics predictions. The cross-sections were obtained for nuclear reactions induced by neutrons and protons at energies up to 1 GeV

Double Differential Hydrogen and Helium Production Cross Section of Oxygen and Nitrogen for 75 MeV Neutrons

Double differential (n,xp), (n,xd), (n,xt) and (n,xα) cross sections of oxygen and nitrogen were measured for 75 MeV incident neutrons at 25°, 65° and 125° angles using a specially designed spectrometer. The spectrometer has three counter telescope consisting of a low pressure gas proportional counter, a thin SSD and a BaF2 scintillator. The energy dependence of the BaF2 was calibrated with direct proton, deuteron and helium beams. The results were compared with the LA-150 data library. The library represents the experimental results of proton, triton and α-particle generally well, but shows the marked difference in the high energy part of deuteron one.

Accelerated helium and hydrogen production in 54Fe doped alloys – measurements and calculations for the FIST experiment

F-82H alloys isotopically enriched in 54Fe up to 86% were irradiated in the high flux isotope reactor (HFIR) to determine the accelerated production of helium and hydrogen due to isotopic effects. Results are compared to calculations using isotopic helium production cross-sections from ENDF/B-VI or GNASH and measured neutron spectra. Helium measurements demonstrated an accelerated helium (appm)/dpa ratio of 2.3 after a 1.25-year irradiation, an increase of a factor of 4.3 over natural iron. The accelerated helium production is due to higher helium production cross-sections for 54Fe and 55Fe. Alloys doped with 55Fe could achieve helium/dpa ratios up to about 20, well above the fusion reactor ratio of 10. Hydrogen measurements were performed using a newly developed quadrupole mass spectrometer system at PNNL. Calculations predict that hydrogen production will be accelerated by about a factor of 13 over natural iron. However, measurements show that most of this hydrogen is not retained in the samples.

Data base for radiation damage analysis of advanced transmutors

The new cross-section data library BISERM2 elaborated for radiation damage analysis is described. Data base contains neutron induced displacement, hydrogen and helium production cross-sections for 259 stable isotopes of structural materials from aluminum to bismuth for energy range up to 1 GeV, and displacement cross-sections for most important alloys, namely Zircaloy, Inconel and various types of stainless steel.

Measurement of Proton-Induced Helium Production Cross Sections for Aluminum and Nickel below 16 MeV

Proton-induced He production cross sections, (p, He), for Al and Ni have been measured up to 16MeV by using a He accumulation method.The reliability of the present experiment was confirmed by performing three kinds of experiments for the Al(p, He). The sample structure or the manner of measuring the number of bombarding protons differs in each experiment. A comparison of their results shows that it is valid to install an Al sample in a Faraday cup for determination of the absolute number of incident protons and to sandwich a sample sheet by two Au foils to catch outgoing α-particles from the sample surface layer for measuring the all He produced in the sample.

Measurement of Helium Production Cross Sections of Stainless Steels for 14 MeV Neutrons

Helium production cross sections of the austenitic stainless steels, Type 316 stainless steel, JPCA, and JPCA2, and the ferritic/martensitic stainless steels, HT-9, and JFMS have been measured for 14.5MeV neutrons, employing a helium accumulation method. The measured effective cross sections range from 52 to 59 mb with ±8% error and have been compared with the composite values which are calculated from measured or estimated He production cross sections for individual constituent elements. The measured effective cross sections agree well with the composite cross sections. The contributions from constituent elements to the composite cross sections were compared. As a result, the comparison shows that the carbon content of the stainless steel has a significant effect on the He production rate.

Measurement of Helium Production Cross Sections of Stainless Steels for 14 MeV Neutrons.

Helium production cross sections of the austenitic stainless steels, Type 316 stainless steel, JPCA, and JPCA2, and the ferritic/martensitic stainless steels, HT-9, and JFMS have been measured for 14.5MeV neutrons, employing a helium accumulation method. The measured effective cross sections range from 52 to 59 mb with ±8% error and have been compared with the composite values which are calculated from measured or estimated He production cross sections for individual constituent elements. The measured effective cross sections agree well with the composite cross sections. The contributions from constituent elements to the composite cross sections were compared. As a result, the comparison shows that the carbon content of the stainless steel has a significant effect on the He production rate.

Measurement of Proton-Induced Helium Production Cross Sections for Aluminum and Nickel below 16MeV.

Proton-induced He production cross sections, (p, He), for Al and Ni have been measured up to 16MeV by using a He accumulation method.The reliability of the present experiment was confirmed by performing three kinds of experiments for the Al(p, He). The sample structure or the manner of measuring the number of bombarding protons differs in each experiment. A comparison of their results shows that it is valid to install an Al sample in a Faraday cup for determination of the absolute number of incident protons and to sandwich a sample sheet by two Au foils to catch outgoing α-particles from the sample surface layer for measuring the all He produced in the sample.

Helium Production by 9.85-MeV Neutrons in Elemental Iron, Nickel, and Copper and in56Fe and58,60,61Ni

Neutron-induced helium production, which can contribute substantially to radiation damage, is an important parameter in the choice of structural materials and other component materials for both fusion and fission reactors. Here, helium production cross sections for the elements iron, nickel, and copper and for the isotopes {sup 56}Fe, {sup 58}Ni, {sup 60}Ni, and {sup 61}Ni for 9.85-MeV neutrons have been measured by irradiation with an intense, quasi-monoenergetic neutron source followed by helium analysis with isotope dilution gas mass spectrometry. The results are in fair agreement with (n, {alpha}) cross sections measured by alpha-particle detection and integration over the alpha-particle energies and angular distributions.

A system for measurement of sub-parts-per-trillion helium in solids

A system for measurement of less than 1 ppt (parts per trillion) of helium contained in a solid within the range of mass between 100 mg and 1 g has been developed for the primary purpose of measuring neutron-induced helium production cross sections. The system consists of an apparatus based on ultrahigh vacuum techniques, computer codes to estimate suitable parameters for the given experimental conditions and to control data acquisition parts, and an appropriate routine of operation of the system. The system apparatus consists of a gas releaser, a mass spectrometer, and a standard helium supply. A sample containing helium is evaporated in the gas releaser and the gas is analyzed with the mass spectrometer after purifying it for helium to decrease background gases. The background of helium for a dummy sample of silicon is measured to be 0.04 ppt. The total uncertainty of the apparatus is 4.4% in the range of (0.5–5.0)×1010 He measurement.

Calculation of displacement, gas, and transmutation production in stainless steel irradiated with spallation neutrons

Calculations using the high-energy transport code LAHET have been made for the production of displacements, helium gas, and transmuted atoms for stainless steel (Fe-18 wt% Cr-10 wt% Ni) irradiated with spallation neutrons at energies of 100 to 1600 MeV. The damage energy cross section increased from about 250 to 350 b keV for increasing neutron energies from 100 to 1600 MeV with a spallation spectrum average of 281 b keV. For a displacement threshold energy of 33 eV, the corresponding spectrum-average displacement cross section is 3400 b. The PKA spectrum was found to be fairly independent of the incident neutron energy, with an average damage energy of 0.25–0.30 MeV. The helium production cross section increased monotonically with increasing neutron energy with a spectrum average of 0.32 b. The maximum transmutation yield was observed near manganese ( Z = 25), corresponding to a production cross section of about 0.2 b. Relevance to fusion materials is discussed.

Helium production cross sections in structural materials irradiated by protons and neutrons at energies up to 800 MeV

Abstract The proton and neutron helium production cross sections have been obtained for a number of structural materials in the energy range between 10 and 800 MeV. The cross-section calculations have been carried out using the DIDACS/90 code package and the ALICE/ASH code. Some features of high energy helium production cross-section calculations are discussed.

Neutron displacement cross-sections for structural materials below 800 MeV

Neutron displacement cross-sections at energies of 15 to 800 MeV have been calculated for the main structural materials. Good agreement between the preequilibrium exciton model and intranuclear cascade evaporation model calculations has been achieved at energies around 20 MeV. A brief description of the DIDACS computer code developed for calculations of displacement cross-sections, as well as hydrogen and helium production cross-sections in the high energy region, is given. Specific features of neutron displacement cross-section calculation at high energies are discussed.

A new technique for enhancing helium production in ferritic materials

Abstract Analyses of iron samples irradiated up to 1027n/m2 in HFIR found more helium than was expected from fast neutron reactions at high neutron fluences. The helium excess increased systematically with neutron exposure, suggesting a transmutation-driven process. The extra helium may be produced in two different ways, either by fast neutron reactions on the transmuted isotopes of iron or by a thermal neutron reaction with the radioactive isotope 55Fe. Radiometric and mass spectrometric measurements of the iron isotopes composing the irradiated samples have been used to determine limits on the cross sections for each process. Either of these processes can be used to enhance helium production in ferritic materials during irradiations in mixed-spectrum reactors by isotopically enriching the samples. Further work is needed to clarify the reaction mechanisms and helium-production cross sections. Our measurements determined the thermal neutron total absorption cross section of 55Fe to be 13.2 ± 2.1 barn.

New ideas in dosimetry and damage calculations for fusion materials irradiations

Nuclear data and techniques are being developed to improve our ability to characterize fusion materials irradiations. The production of long-lived isotopes have been measured near 14 MeV, including reactions from AI, Fe, and Mo to 26A1, 53Mn, and 94Nb, respectively. These data can be used for fusion reactor activation, dosimetry, and plasma diagnostics. Dosimetry cross sections can be adjusted using measurements at Be(d,n) sources ( E d = 7–40 MeV ) and mono-energetic neutron sources from 1 to 14 MeV. Helium production cross sections are being tested at all fusion irradiation facilities. We have recently discovered a new thermal helium production in copper, similar to the well-known effect in nickel. Recommended cross sections and procedures are included. A new program SPECOMP has been developed to calculate displacement damage for compounds. This program uses the SPECTER recoil atom distributions and integrates over secondary displacement functions for each combination of incident ion and matrix material to determine displacement cross sections for alloys, insulators, and breeder materials.

Helium Production in Pure Elements, Isotopes, and Alloy Steels by 14.8-MeV Neutrons

The results of an extensive series of total helium production cross-section measurements for incident neutrons in the 14- to 15-MeV energy region are presented, and an experimental data base for th...