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Sample records for am-be isotopic neutron

  1. Determination of vanadium, manganese and tungsten in steels with an 241 Am-Be isotopic neutron source

    International Nuclear Information System (INIS)

    A non-destructive neutron activation method was developed for determination of vanadium, manganese, and tungsten in alloy-steel, with the aid of an Am-Be 1,85x1011Bq(5Ci) isotopic neutron source, employing NaI (T1) detector well type 2x2 in. The 51V (n,γ) 52V, 55Mn (n,γ) 56Mn, and 186W (n,γ) 187W nuclear reactions are induced in steel samples subject to activation by thermal neutron. After irradiation, the activity of the samples was measured by γ-spectrometry under the 1434 KeV 52V, 847KeV 56Mn, and 686 KeV 187W photopeaks. Possible interferences due to other radionuclides activity were investigated by determining the 52V, 56Mn, and 187W half-lifes. The time of analysis for vanadium determination was 11 min, with 1,5% of precision and 3,4% of average absolute deviation. The time of analysis for manganese determination was 22,8 min with 4,0% of precision and 3,4% of average absolute deviation. The time of analysis for tungsten determination was 44,62 min with 3,8% of precision and 3,1% of average absolute deviation. The activation analysis method is adequated for steel quality control in industry. (Author)

  2. Characterization of the neutron field from the 241Am-Be isotopic source of the IPHC irradiator

    International Nuclear Information System (INIS)

    A measurement campaign has been carried out recently to provide the source intensity and the reference spectra around a neutron irradiation facility based on 241Am-Be radionuclide source, using the UAB Bonner Sphere Spectrometer. This facility, which consists of a bunker, a container/shielding for the source and an irradiation device that uses an automated remote-controlled system for the source positioning and rotating during the dosimeter irradiation, is intended to be routinely used to check the response of passive dosimeters, namely those based on photo-stimulated imaging plates and solid-state nuclear track detectors. The measurement results, in terms of neutron spectra and global dosimetric quantities (i.e., fluence and ambient dose equivalent rates) at different distances with respect to the 241Am-Be source, were compared with Monte Carlo simulations using the MCNPX code and a good agreement was observed. An estimation of the un-scattered neutron spectrum directly emitted from the 241Am-Be source is given as well. - Highlights: ► We describe a neutron irradiation facility based on 241Am-Be radioactive source. ► The neutron field was characterized with a Bonner sphere spectrometer (BSS). ► Monte Carlo simulations using the MCNPX code were in good agreement with BSS. ► The un-scattered neutron spectrum is provided and compared to that given by the ISO-8529 standard. ► The neutron intensity of the 241Am-Be source is also estimated

  3. Characterization of neutron flux spectra in the irradiation sites of a 37 GBq {sup 241}Am-Be isotopic source

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, Haluk [Ankara University, Institute of Nuclear Sciences, 06100 Tandogan, Ankara (Turkey); Budak, Mustafa Guray, E-mail: mbudak@gazi.edu.tr [Gazi University, Gazi Education Faculty, 06500 Teknikokullar, Ankara (Turkey); Karadag, Mustafa [Gazi University, Gazi Education Faculty, 06500 Teknikokullar, Ankara (Turkey); Yüksel, Alptuğ Özer [Ankara University, Institute of Nuclear Sciences, 06100 Tandogan, Ankara (Turkey)

    2014-11-01

    Highlights: • An irradiation unit was installed using a 37 GBq {sup 241}Am-Be neutron source. • The source neutrons moderated by using both water and paraffin. • Irradiation unit was shielded by boron oxide and lead against neutrons and gammas. • There are two sites for irradiations, one of them has a pneumatic transfer system. • Cadmium ratio method was used for irradiation site characterization. - Abstract: For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37 GBq {sup 241}Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (φ{sub th}) and epithermal neutron fluxes (φ{sub epi}), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be φ{sub th} = (2.11 ± 0.05) × 10{sup 3} n cm{sup −2} s{sup −1}, φ{sub epi} = (3.32 ± 0.17) × 10{sup 1} n cm{sup −2} s{sup −1}, f = 63.6 ± 1.5, α = 0.045 ± 0.009, respectively. Similarly, those parameters were measured in site #2 as φ{sub th} = (1.49 ± 0.04) × 10{sup 3} n cm{sup −2} s{sup −1}, φ{sub epi} = (2.93 ± 0

  4. Characterization of neutron flux spectra in the irradiation sites of a 37 GBq 241Am-Be isotopic source

    International Nuclear Information System (INIS)

    Highlights: • An irradiation unit was installed using a 37 GBq 241Am-Be neutron source. • The source neutrons moderated by using both water and paraffin. • Irradiation unit was shielded by boron oxide and lead against neutrons and gammas. • There are two sites for irradiations, one of them has a pneumatic transfer system. • Cadmium ratio method was used for irradiation site characterization. - Abstract: For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37 GBq 241Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (φth) and epithermal neutron fluxes (φepi), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be φth = (2.11 ± 0.05) × 103 n cm−2 s−1, φepi = (3.32 ± 0.17) × 101 n cm−2 s−1, f = 63.6 ± 1.5, α = 0.045 ± 0.009, respectively. Similarly, those parameters were measured in site #2 as φth = (1.49 ± 0.04) × 103 n cm−2 s−1, φepi = (2.93 ± 0.15) × 101 n cm−2 s−1, f = 50.9 ± 1.3 and α = 0.038 ± 0.008. The results for f-values indicate

  5. Recovery of 241Am/Be neutron sources, Wooster, Ohio

    International Nuclear Information System (INIS)

    In August 1997, the Nuclear Regulatory Commission (NRC) submitted to the US Department of Energy (DOE) a partial list of licensed radioactive sealed sources to be recovered under a pilot project initiating Radioactive Source Recovery Program (RSRP) operations. The first of the pilot project recoveries was scheduled for September 1997 at Eastern Well Surveys in Wooster, Ohio, a company with five unwanted sealed sources on the NRC list. The sources were neutron emitters, each containing 241Am/Be with activities ranging from 2.49 to 3.0 Ci. A prior radiological survey had established that one of these sources, a Gulf Nuclear Model 71-1 containing 3 Ci of 241Am, was contaminated with 241Am and might be leaking. The other four sources were obsolete and could no longer be used by Eastern Well Surveys for their intended application in well-logging applications due to NRC decertification of these sources. All of the sources exceeded the limits established for Class C waste under 10 CFR 61.55 and, as a result, are the ultimate responsibility of the DOE under the provisions of PL 99-240. This report describes the cooperative effort between the DOE and NRC to recover the sources and transport them to Los Alamos National Laboratory (LANL) for deactivation under the RSRP. This operation alleviated any potential risk to the public health and safety from the site which might result from the leaking neutron sources or the potential mismanagement of unwanted sources. The on-site recovery occurred on September 23, 1997, and was performed by personnel from LANL and its contractor and was observed by staff from the Region III office of the NRC. All aspects of the recovery were successfully accomplished, and the sources were received at LANL on September 29, 1997. Experience gained during this operation will be used to formulate operational poilicies and procedures which will contribute to the eventual routine recovery operations of a full-scale RSRP

  6. Characterization of the neutron field of the 241AmBe in a calibration room

    International Nuclear Information System (INIS)

    The field of neutrons produced by an isotopic source of neutrons of 241 Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  7. Installation and measurement capacity of 3 x 592 GBq 241Am-Be neutron irradiation cell

    International Nuclear Information System (INIS)

    In this study, the installation and measurement capacity of the neutron irradiation system are investigated. First of all an irradiation geometry enabling optimum irradiation was designed for three 241Am-Be sources each of it having 592 GBq activity. Neutron irradiation system was installed after design and optimization of the system including the design of appropriate moderator and shielding were completed. Radiation safety standards of the Neutron Research Laboratory fulfilling the requirements of national regulation were achieved with unique configuration of the shielding materials. In this study the results of qualitative and quantitative detection limits obtained for Na, Al, Cl, K, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Mo, Ru, Ag, Cd, In, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Lu, Hf, W, Pt, Au, Th and U elements by using the neutron irradiation cell comprising 3 x 592 GBq 241Am-Be isotopic neutron source are presented and discussed. (orig.)

  8. Am-Be Neutron Irradiator Used for Nuclear Instrumentation Training

    International Nuclear Information System (INIS)

    A neutron irradiator was assembled at IPEN (Nuclear and Energy Research Institute) facility to perform qualitative- quantitative analysis of materials, using thermal and fast neutrons. In order to determine the 116mIn decay constant, a thermal flux obtained experimentally by Monte Carlo N-Particle Transport Code-MCNP, in a previous work, was used in the nuclear experiment. The activity calculated from the activation parameters was 13.51±0.17 kBq and the activity determined experimentally was 12.51± 0.36 kBq. The decay constant determined by the pulse height analyzer (PHA) measures was 211.4 μ.s-1, and that determined by fitting the data using a Multichannel Scaler (MCS) system was 200.3 ± 1.6 μ.s-1. The half-life of 116mIn found in the literature is 3256.8 s, which corresponds to a decay constant of 212.8 μ.s-1. The present experiment does not intend to establish a new value for the decay constant: it solely aims students' practical exercises in nuclear properties of elements. This experiment is part of the nuclear experimental course. (authors)

  9. The k0-NAA Standardization Method Using an Am-Be Neutron Source

    International Nuclear Information System (INIS)

    Instrumental neutron activation analysis is a well established technique for the analysis of trace elements in different samples. Precise elemental concentrations of Al, Mn, Mg and Na in two unknown geological samples were determined by using the k0-standardization method. For such measurements two sets of standard monitors of Gold (Au), Indium (In), Tungsten (W) and Titanium (Ta) were used. One set is bare and the other is cadmium covered. These monitors were used for measuring the irradiation position factors f and α and using the cadmium ratios of the 115In(n,γ)116In and 182Ta(n,γ)183Ta interactions. Neutrons were obtained from CNIF2 facility that uses an Am-Be radio-isotopic neutron source with a modification to have thermal and epi-thermal neutrons. Measurements were carried out using a gamma-ray spectrometer consisting of a hyper pure germanium detector and necessary associated electronics. The k0-standardization method can be used for quality control tests.

  10. Nuclear data measurements in 3x592 GBq 241Am-Be neutron cell

    International Nuclear Information System (INIS)

    The aim of this study is to present the results of the activities carried out within the scope of the Nuclear Data Measurements in 3x592 GBq Am-Be Neutron Cell project. The study covers the establishment of neutron irradiation systems, neutron and gamma dose rate evaluations in and around the laboratory, performance measurements of neutron irradiation systems, measurements of thermal, epithermal and fast neutron flux, gamma spectrometer efficiency calibrations, fast neutron fission product yield measurements for fertile nuclides (232Th and 238U), cross section measurements for fast neutron threshold detectors, gamma ray intensity measurements of the nuclides in uranium decay chain, elemental detection limit measurements and the half life measurement of short-lived isotopes. First of all, an irradiation geometry, which enables optimum irradiation, was designed for an irradiation system of 3 241Am-Be sources with 592 GBq activity each. Paraffin was chosen in order to slow down the source neutrons. An equilateral quadrangle with 70 cm side length and 60 cm height was used as paraffin moderator. Experimentally, it was determined that paraffin with approximately 3.5 cm thickness slows down to maximum thermal neutron flux of 241Am-Be neutrons. Paraffin block was placed on the base of the source room. In order to determine the positions of thermal and fast neutron irradiations, indium wires were irradiated with 5 mm intervals vertically parallel to the neutron sources in thermal and fast neutron irradiation cells. The position of maximum thermal and fast neutron fluxes is 61.5 cm for the thermal neutron irradiation cells and 69 cm for the fast neutron irradiation cell, from the top of the irradiation pipes down. One of the most important parameters of nuclear data measurements is the counting efficiency of the gamma spectrometer used for each counting geometry. For this reason, the detector efficiencies for the related counting geometries need to be measured accurately

  11. Neutron beam preparation with Am-Be source for analysis of biological samples with PGNAA method

    International Nuclear Information System (INIS)

    Material analysis with prompt gamma neutron activation analysis (PGNAA) requires a proper geometrical arrangement for equipments in laboratory. Application of PGNAA in analysis of biological samples, due to small size of sample, needs attention to the dimension of neutron beam. In our work, neutron source has been made of 241Am-Be type. Activity of 241Am was 20 Ci which lead to neutron source strength of 4.4 x 107 neutrons per second. Water has been considered as the basic shielding material for the neutron source. The effect of various concentration of boric acid in the reduction of intensity of fast and thermal components of the neutron beam and gamma ray has been investigated. Gamma ray is produced by (α, n) reaction in Am-Be source (4.483 MeV), neutron capture by hydrogen (2.224 MeV), and neutron capture by boron (0.483 MeV). Various types of neutron and gamma ray dosimeters have been employed including BF3 and NE-213 detectors to detect fast and thermal neutrons. BGO scintillation detector has been used for gamma ray spectroscopy. It is shown that the gamma and neutron radiation dose due to direct beam is of the same magnitude as the dose due to radiation scattered in the laboratory ambient. It is concluded that 14 kg boric acid dissolved in 1,000 kg water is the optimum solution to surround the neutron source. The experimental results have been compared with Monte Carlo simulation. (author)

  12. Calculation of anisotropy factors for 241Am-Be neutron sources

    International Nuclear Information System (INIS)

    The authors calculated anisotropy factors for 241Am-Be neutron sources used for calibration of neutron-measuring devices for radiation protection purpose. In this calculation, we created a calculation model composed of following three steps: (1) calculation of α-particle spectrum at the surface of spherical cluster of AmO2, (2) calculation of neutron yield in a thick beryllium target and of neutron spectrum produced by 8Be (α,n) reactions; and (3) calculation of angular fluence distribution of neutrons emerging from two different encapsulation types of 241Am-Be neutron sources. This computation was made by combining an in-house code using the 9Be(α,n) cross section data library (JENDL/AN-2005) and the Monte Carlo code MCNP-4C. As a result, anisotropy factors in the direction perpendicular to the source capsule axis were evaluated to be 1.030 and 1.039 for 241Am-Be in a standard Amersham X3 capsule and X4 capsule, respectively. These values are in reasonable close agreement with the published experimental data. If the support structures are included in the simulation, the anisotropy factors for these neutron sources increase by about 10%. (author)

  13. On replacing Am-Be neutron sources in compensated porosity logging tools

    International Nuclear Information System (INIS)

    Full text: The authors are investigating potential replacements for the Americium-Beryllium (Am-Be) neutron source that has been used in neutron porosity logs. Am-Be sources are hazardous and would, therefore, be attractive to terrorists attempting to construct and use radiological dispersal devices (RDDs). This aspect of Am-Be sources makes them undesirable for industrial uses like well logging and in time may increase the difficulties in obtaining licenses for them. There has recently been a National Academy of Sciences Committee commissioned by Congress to author a report on Radiation Source Use and Replacement. This report is expected to be released very soon. There has also been a recent shift in the supplier of these sources to Russia, which represents possible problems in both supply and cost. These concerns led us to initiate the present study on possible replacements for the existing technology of using Am-Be sources in compensated porosity logs. Monte Carlo radiation transport simulations have been conducted with MCNP5 to investigate the responses of a typical wireline compensated neutron porosity logging tool. These results were compared to simulations where the Am-Be source was replaced with a 252Cf spontaneous fission neutron source and a deuterium-tritium fusion-based accelerator neutron source. The average energy of the 252Cf sources is about 2.1 MeV while that from an Am-Be source is about 4.2 MeV. However, the average neutron energy is not the entire story since a range of energies is involved with both the 252Cf and Am-Be sources. We are trying to investigate this problem from a fundamental point of view with the objective of understanding the phenomena underlying the compensated neutron porosity log. Both of these alternative sources would represent significantly reduced hazards in the possible terrorist purpose. A novel method involving the segmenting of the detectors used in the MCNP5 code has been developed to optimize detector spacing for the

  14. The investigation of Am-Be neutron source shield effect used on landmine detection

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei Ochbelagh, D. [Department of Physics, Faculty of Sciences, University of Mohagheg Ardebily, P.O. Box 179, Ardebil (Iran, Islamic Republic of)]. E-mail: ddrezaey@yahoo.com; Miri Hakimabad, H. [Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Najafabadi, R. Izadi [Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2007-07-11

    In this work, experiments were carried out to investigate the possible use of neutron backscattering for the detection of sample buried in the soil. A series of Monte Carlo simulations were performed to study the complexity of the neutron backscattering process and to optimize the source shield thickness. The results of these simulations indicate that neutron source shield plays an important role for the detection of nonmetallic landmines. This paper experimentally demonstrates, by using suitable shield around Am-Be neutron source, the increase of signal-to-noise ratio up to 130%.

  15. Characterization of the neutron field of the {sup 241}AmBe in a calibration room; Caracterizacion del campo de neutrones del {sup 241} AmBe en una sala para calibracion

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain)] e-mail: rvega@cantera.reduaz.mx

    2003-07-01

    The field of neutrons produced by an isotopic source of neutrons of {sup 241} Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  16. Development Of K0-INAA Standardization Method By Neutron Activation With Am-Be Source

    International Nuclear Information System (INIS)

    Method of k0 standardization in neutron activation analysis with Am-Be neutron source at DNP, University of Sciences, VNU-HCMC, have been researched and developed. In this paper, the parameters of neutron spectrum of Am-Be source such as epithermal neutron spectrum deviation (α), cadmium ratio (RCd) and ratio of fluxes of thermal/epithermal neutron (f) at thermal neutron irradiation position were measured by cadmium ratio method with dual monitors as Au and Mo, which actual were α = 0.075 ± 0.011, f 25.73 ± 2.20 and RCd,Au = 2.95 ± 0.12. HPGe detector efficiency curves for samples of cylinder and foil geometries were experimentally determined by home-made production of radioisotope 116mIn through neutron irradiation of 115In(n, γ)116mIn reaction. Application of k0 standardization method to concentration analytic of elements such as Al, Mn and Na in cement samples were carried out as well. Obtained elements concentration in this research was fairly agreed with other analyses. (author)

  17. Measurement of partial neutron spectrum of an Am-Be (α,n) source

    International Nuclear Information System (INIS)

    A partial neutron spectrum from an Am-Be (α,n) source has been measured by TOF accompanied with γ-ray. In the experiment the 4.43 MeV γ-ray comes from the reaction of 9Be(α,n)13Csup(*) (13Csup(*)(61fs)→12C+n+γ(4.43 MeV)). The result has been compared with others. (author)

  18. Preliminary experiment of the controllable Am-Be neutron source based on composite polymeric membrane

    International Nuclear Information System (INIS)

    A controllable Am-Be neutron source was designed based on a hamburger structure including two Be pallets and a composite polymeric membrane carrying 241Am. The composite polymeric membrane was made of polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA). PVDF polymeric membrane was used as the base film to load the mixed Am(NO3)3-PVA solution, which was coated on the PVDF polymeric membrane. The thickness of two layers was both about 5 μm. The correlative calculations were performed using the Geant4 code. A piece of composite membrane loading 241Am of 2.13 × 106 Bq was placed in the middle of two Be pallets just like a hamburger. Neutrons were produced continuously until the composite membrane was separated from Be pallets. The neutron yield of the controllable hamburger neutron source was measured as 54 n/(106α), which was 15.6 % lower than the calculation value. (author)

  19. Prompt gamma-ray neutron activation analysis (PGNAA) system by using a 740 GBq 241Am-Be neutron source

    International Nuclear Information System (INIS)

    A PGNAA system consisting of a 740 GBq 241Am-Be neutron source and a gamma spectrometer with a n-type Ge (REGe) detector was installed at Ankara Nuclear Training and Research Center to measure the prompt gamma-rays produced by the interactions of thermal neutrons in the samples for the analysis of light elements such as B, P, S and Cl, and some trace elements with large cross sections (Cd, Hg, Sm, Gd, etc.). In the irradiation system, a 55 cm diameter cylinder tank filled with the water moderator comprises the neutron source placed in a polypropylene tube that was positioned in lead rings (internal diameter - 9 cm and outer diameter - 21 cm) in order to reduce the gamma rays emitted from the source such as 0.0596 MeV (241Am) and 4.43 MeV (0.6 gamma per neutron) from the 9Be(α, n) reaction in the source. The moderator tank was shielded with paraffin in all sides against fast neutrons. The thickness of paraffin at the front side of the tank is 28 cm and 18 cm at other sides. The neutron irradiation system was also shielded by using chevron lead bricks of 18 cm thickness. The background-prominent gamma-rays which is especially the 2.223 MeV gamma ray from the 1H(n, γ) reaction formed in hydrogenous materials used for neutron moderation was reduced remarkably in view of the permissible gamma dose for overall irradiation room. The neutrons thermalized in moderator travel through the hole with 6 cm diameter for the sample irradiation. The detector was shielded with Li2CO3 powder against thermal neutrons to avoid radiation damage and surrounded by additional lead bricks to reduce gamma-background. The measurements are carried out for efficiency calibration of the detector by using the standard source. The characteristics of PGNAA system with the isotopic neutron source and its analysis capability are discussed

  20. Collimator duct for neutron radiographs using a source of 241Am-Be

    International Nuclear Information System (INIS)

    With the aim of designing a collimator system to realize Neutron Radiographs using source of 241Am-Be, a collimator was designed using two removable modules. One parameter of merit to be considered in the building of a collimator is the intensity of the neutron beam on the image plane. Therefore, the choice of the inner coating material is of utmost importance. As the scattered neutrons can reduce the resolution of the neutron radiographic image, it would be opportune to capture them so that the neutron beam is aligned. Thus, an aligning module made of an absorbent material was designed, to coat the wall end extensions of the collimator. Two other parameters are essential to configure a collimator system: the length, L, and diameter of the opening, D. Geometric resolution of the neutron radiographic image is defined by the ratio L/D, as well as the neutron flux on the image plane. Simulations with code MCNP-4B were conducted to select the geometry of the collimator, the materials for the structure and coating and the dimensions for the L and D parameters and aluminum was chosen as the structural material and cadmium for coating. (author)

  1. Performance comparison of an 241Am-Be neutron source-based PGNAA setup with the KFUPM PGNAA setup

    International Nuclear Information System (INIS)

    Monte Carlo calculations have been carried out to compare the performance of an 241Am-Be neutron source-based prompt gamma neutron activation analysis (PGNAA) setup with that of the 2.8 MeV neutron-based PGNAA setup at King Fahd University of Petroleum and Minerals (KFUPM) to analyze Portland cement samples. This work is a part of a wide Monte Carlo studies being conducted at KFUPM in search of a more efficient neutron source for its 2.8 MeV neutrons, from the D(d,n) reaction, based PGNAA facility. In this study an 241Am-Be neutron source-based PGNAA setup was simulated. For comparison, the diameter of a cylindrical external moderator of the 241Am-Be neutron source, based PGNAA setup, was assumed to be similar to that used in the KFUPM PGNAA setup. It was revealed that although the optimum geometry of the 241Am-Be neutron source-based setup is similar to that of the KFUPM PGNAA facility, the performance of the 241Am-Be neutron source-based setup is slightly poorer than that of the 2.8 MeV neutron-based setup. (author)

  2. 50 curie Am-Be neutron source in determining impurities in various materials

    International Nuclear Information System (INIS)

    The neutrons from a 50 Curies Am-Be neutron source after being thermalized have been used to study the impurities in various materials by measuring the gamma rays emitted from the activated samples. To get good resolution two HPGe detectors, one of them suitable for low energy gamma rays as well as X-rays and the other suitable for measuring the gamma-ray energies up to 10 MeV have been used. The resolution of the detectors were measured and proved to be better than 1.8 keV for 60Co gamma rays. During the measurements the detectors were placed in thick lead chambers. In these chambers the background was reduced dramatically. To make the whole system safe and also for saving time in activation analysis a fully computerized control rabbit device has been coupled to the system. Our main purpose is to set up a portable, cheap and reliable system for activation analysis for research institutions that are not able to have reactors due to various reasons. Although our tests and analysis is still in progress we think that the system is very promising. In this paper we will discuss about the details and the future prospects. (author)

  3. Integral cross section measurements of a few threshold reactions induced by Am/Be neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, Md. Shuza; Hossain, Syed Mohammad; Rumman-Uz-Zaman, Md. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Institute of Nuclear Science and Technology (INST); Spahn, Ingo; Qaim, Syed M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5); Rakib-Uz-Zaman, Md. [Rajshahi Univ. (Bangladesh). Dept. of Applied Chemistry and Chemical Engineering

    2015-07-01

    Integral cross sections of the reactions {sup 46}Ti(n,p){sup 46}Sc, {sup 47}Ti(n,p){sup 47}Sc, {sup 48}Ti(n,p){sup 48}Sc, {sup 60}Ni(n,p){sup 60}Co and {sup 64}Zn(n,p){sup 64}Cu were measured with fast neutrons (E{sub n} > 1.5 MeV) from an Am/Be source. The results were compared with data calculated using the neutron spectral distribution and the excitation function of each reaction given in the data libraries ENDF/B-VII.0, IRDF-2002, JEFF-3.2 and JENDL-4.0. In general, the integral measurement and the integrated value agreed within ±4%, except for the {sup 46}Ti(n,p){sup 46}Sc reaction where JEFF-3.2 shows a deviation of 7% and the {sup 60}Ni(n,p){sup 60}Co reaction where ENDF/B-VII.0 and IRDF-2002 exhibit deviations upto 8%.

  4. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    International Nuclear Information System (INIS)

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV γ-rays from a 137Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with our previous result from a neutron generator demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source

  5. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    CERN Document Server

    Lee, H S; Choi, J H; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, G B; Kim, H J; Kim, K W; Kim, S C; Kim, S K; Kim, Y D; Kim, Y H; Lee, J H; Lee, J K; Leonard, D S; Li, J; Myung, S S; Olsen, S L; So, J H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with similar result from a neutron reactor demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source.

  6. A quantitative PGNAA study for use in aqueous solution measurements using Am-Be neutron source and BGO scintillation detector

    Science.gov (United States)

    Ghal-Eh, N.; Ahmadi, P.; Doost-Mohammadi, V.

    2016-02-01

    A prompt gamma neutron activation analysis (PGNAA) system including an Am-Be neutron source and BGO scintillation detector are used for quantitative analysis of bulk samples. Both Monte Carlo-simulated and experimental data are considered as input data libraries for two different procedures based on neural network and least squares methods. The results confirm the feasibility and precision of the proposed methods.

  7. Measurement of thermal neutron cross-sections and resonance integrals for sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As by using sup 2 sup 4 sup 1 Am-Be isotopic neutron source

    CERN Document Server

    Karadag, M; Tan, M; Oezmen, A

    2003-01-01

    Thermal neutron cross-sections and resonance integrals for the sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As reactions were measured by the activation method. The experimental samples with and without a cylindrical Cd shield case in 1 mm wall thickness were irradiated in an isotropic neutron field of the sup 2 sup 4 sup 1 Am-Be neutron source. The induced activities in the samples were measured by high-resolution gamma-ray spectrometry with a calibrated reverse-electrode germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As reactions have been obtained relative to the reference values, sigma sub 0 =13.3+-0.1 b and I sub 0 =14.0+-0.3 b for the sup 5 sup 5 Mn(n,gamma) sup 5 sup 6 Mn reaction as a single comparator. The necessary correction factors for gamma attenuation, thermal neutron and resonance neutron self-shielding effects were taken into...

  8. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    OpenAIRE

    Lee, H. S.; Bhang, H.; Choi, J.H.; Choi, S.; Hahn, I. S.; Jeon, E. J.; Joo, H. W.; Kang, W. G.; Kim, G. B.; Kim, H. J.; Kim, K. W.; Kim, S.C.; Kim, S K; Kim, Y.D.(Center for Underground Physics, Institute for Basic Science (IBS), Daejon, 305-811, Korea); Kim, Y H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) be...

  9. Study of neutron moderation using the {sup 241}Am-Be spectrum with hydrogenated materials; Estudo da moderacao de neutrons utilizando o espectro de {sup 241}Am-Be com materiais hidrogenados

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.R.L.; Silva, F.S.; Martins, M.M.; Pereira, W.W., E-mail: aleiras@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ/LNMRI/LN), Rio de Janeiro, RJ (Brazil). Lab. de Neutrons; Freitas, B.M. [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Tavares, D.Y.S. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This work intends to assess materials for moderation of neutrons, trying to reduce the rate of H{sub p}(10) and H⁎p(10), reducing the effective dose of Occupationally Exposed Workers (OEW) who handle this source daily. The neutron spectra moderated by different materials was performed with a neutron source of {sup 241}Am-Be in an electronic positioning system, using a neutron spectrometry with Bonner Sphere at 50 cm from the center of source. The materials used for moderation were paraffin, silicone and Polyvinyl Chloride (PVC) resin ball. (author)

  10. Measuring neutron energy spectra of 252Cf and Am-Be source with neutron time-of-flight spectrometer with double scintillators

    International Nuclear Information System (INIS)

    We established a neutron time-of-flight spectrometer with double scintillators. It can be used to measure the energy spectra of neutron sources. It is capable of working at above several hundred keV. We measured the energy spectra of 252Cf and Am-Be neutron sources by using this spectrometer. The results obtained were compared to those in other works

  11. Determination of boron in water solution by an indirect neutron activation technique from a 241Am/Be source

    International Nuclear Information System (INIS)

    Boron content in water solutions has been analysed by Indirect Activation Technique a twin 241Am/Be neutron source with a source strength of 9x106 n/seg. The boron concentration was inferred from the measurement of the activity induced in a vanadium flux monitor. The vanadium rod was located inside the boron solution in a standart geometrical set up with respect to the neutron source. Boron concentrations in the range of 100 to 1000 ppm were determined with an overall accuracy of about 2% during a total analysis time of about 20 minutes. Eventhough the analysis is not selective for boron yet due the rapid, simple and precise nature, it is proposed for the analysis of boron in the primary coolant circuit of Nuclear Power Plants of PWR type. (Author)

  12. Determining the neutron spectrum of 241Am-Be and 252Cf sources using bonner sphere spectrometer

    Directory of Open Access Journals (Sweden)

    M.A Varshabi

    2016-06-01

    Full Text Available Bonner spheres system is one of the ways of measuring neutron energy distribution which is often applied in spectrometry and neutron dosimetry. This system includes a thermal neutron detector, being located in the center of several polyethylene spheres, and it is still workable due to the isotropic response of the system which in turn is derived from the spherical symmetry of moderators and the broad measurable range of the energy. In order to practically use this spectrometer, it is necessary to calibrate this system using standard neutron sources. This research aimed to determine the calibration factor of Bonner spheres spectrometry system and energy spectrum of two standard 241Am-Be and 252Cf sources in the atomic energy organization. Calibration and experimental measurement were done via the two standard sources. The response vector of each detector was derived by using MCNPX simulation code, based on the Monte Carlo method. The spectra unfolding of this system was performed through iterative method using the SPUNIT code done in software NSDUAZ6LiI and BUMS. 

  13. Recoiled Proton Track Registration in Polycarbonate Plastic by Irradiation of Neutron from 241Am-Be Radioisotope Source

    International Nuclear Information System (INIS)

    Full text: This research attempts to investigate properties of recoiled proton track registration in polycarbonate (PC) which was irradiated by neutrons from 241Am-Be source. The irradiated PC was etched with PEW solution (15% KOH, 45% H2O and 40% ethyl alcohol) at 70oC for 1 h. The recoiled proton tracks were observed under an optical microscope at approximately 100 times of magnification. The tracks were then characterized by using the Image J program which is an image processing and analysis software. The study showed that the average track density in PC was 2.74 x 105 tracks per square centimeter for a neutron flux of approximately 1.58 x 104neutrons/cm2.s at 2 weeks of irradiation time. The minimum and maximum track areas were found to be 3.443 and 340.698 μm2 while the minimum and maximum track diameters were found to be 4.137 and 20.828μm respectively

  14. Aluminium and copper analysis in metallic alloys by neutron activation analysis from an 241 Am-Be source

    International Nuclear Information System (INIS)

    Aluminium and copper have been determined in aluminium alloys by the method of activation with neutrons from an 241 Am-Be source of intensity 9,8 x 106 n/s. The activity induced due to reactions 27 Al (n, γ)28 Al and 63 Cu (n, γ)64 Cu have been measured with a NaI (Tl) detector coupled to a single channel system. In order to obtain the samples and standards of about the same composition, the material to be irradiated was powdered. In view of low intensity of neutron source it was necessary to use samples of up to 50 g. A series of preliminary irradiations were carried out to ensure that the geometry for the irradiation and for the counting are reproducible. The results have been compared with those obtained by chemical methods. Assuming that the results obtained by chemical method is exact, a maximum relative error of 3,6% is obtained by this method. The method has a good reproducibility. The time needed for analysis of aluminium and copper are 18 min and 2 hours 40 minutes respectively. Four different samples were analysed. The average of five measurements for one of the samples was: 88.0% for aluminium and 10.0% for copper. The standard deviation and coefficient of variation were 0,8 and 1.0% for aluminium and 0,2 and 2.0% for copper. (author)

  15. MCNP simulation of the incident and Albedo neutron response of the IRD Albedo Neutron Dosemeter for 241Am-Be moderated sources

    International Nuclear Information System (INIS)

    The IRD TLD Albedo dosemeter measures both incident and albedo neutron component. The incident to Albedo ratio is used to take into account the energy dependence of its response. In this paper, the behavior of the IRD Albedo dosemeter response as a function of the incident to Albedo ratio for 241Am-Be sources was simulated to improve its algorithm. The simulation was performed in MCNPX transport code and presents a good agreement with experimental measurements. The results obtained in this work are very useful to improve the accuracy of the IRD Albedo dosemeter at real neutron workplace. (author)

  16. NAA of copper in its ores by ''2''4''1Am-Be neutron source using the standard addition technique

    International Nuclear Information System (INIS)

    Neutron activation analysis using nuclear reactors as sources of activating particles is a well established technique, which has been described adequately in the literature and has been used for the analysis of a wide range of materials. The ''2''4''1Am-Be neutron source is also a useful source of activating particles for, although the neutron flux is relatively low (approximately 10''5 ncm''-''2 s''-''1) it is adequate for a range of analyses where extreme sensitivity is not of prime importance and offers the advantages of relatively low cost and ease of operation. The determination of Cu in its ores has been investigated for a typical industrial application of ''2''4''1Am-Be neutron activation by method of standard addition

  17. Characterization of the CRNA Bonner sphere spectrometer based on {sup 6}LiI scintillator exposed to an {sup 241}Am-Be neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Mazrou, Hakim [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria)], E-mail: mazrou_h@comena-dz.org; Sidahmed, Tassadit; Idiri, Zahir; Lounis-Mokrani, Zohra; Bedek, Said [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria); Allab, Malika [Faculte de Physique, Universite des Sciences et de la Technologie Houari-Boumediene (USTHB), Alger (Algeria)

    2008-02-15

    In the present work, measurements have been performed using an available multisphere neutron spectrometer based on a calibrated {sup 6}LiI scintillation detector (10mmox2mm) exposed to an {sup 241}Am-Be neutron source. Sensitive analysis has been performed to assess influence of angle and source-detector distances dependence on the detector responses. Our experimental responses were compared with the published experimental and calculated data for two {sup 241}Am-Be (ISO, PTB) neutron spectra with (4mmox4mm) {sup 6}LiI detector. A discrepancy by a factor of about two was achieved and it is chiefly due to the difference shown in active surface of both detectors.

  18. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    International Nuclear Information System (INIS)

    The neutron emission anisotropy factor of a sealed Americium–Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a “X.3” type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy

  19. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Loreti, S.; Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it

    2015-10-11

    The neutron emission anisotropy factor of a sealed Americium–Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a “X.3” type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy.

  20. Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

    OpenAIRE

    Panjeh Hamed; Hakimabad Hashem M.; Motavalli Lalle R.

    2010-01-01

    The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In ord...

  1. International key comparison of measurements of neutron source emission rate (1999-2005): CCRI(III)-K9.AmBe

    International Nuclear Information System (INIS)

    Section III (neutron measurements) of the Comite Consultatif des Rayonnements Ionisants, CCRI, conducted a key comparison of primary measurements of the neutron emission rate of an 241Am-Be(α,n) radionuclide source. A single 241Am-Be(α,n) source was circulated to all the participants between 1999 and 2005. Eight laboratories participated - the CIAE (China), CMI (Czech Republic), KRISS (Republic of Korea), LNMRI (Brazil), LNE-LNHB (France), NIST (USA), NPL (UK) and the VNIIM (Russian Federation) - with the NPL making their measurements at the start and repeating them near the end of the exercise to verify the stability of the source. Each laboratory reported the emission rate into 4π sr together with a detailed uncertainty budget. All participants used the manganese bath technique, with the VNIIM also making measurements using an associated particle technique. The CMI, KRISS, VNIIM, and later the NPL, also measured the anisotropy of the source although this was not a formal part of the comparison. The first draft report was released in May 2006 and having been discussed and modified by the participants and subsequently reviewed by the CCRI(III), the present paper is now the final report of the comparison. (authors)

  2. Development of a prompt-gamma neutron activation analysis facility for small animal in vivo body composition studies using Am-Be Source

    International Nuclear Information System (INIS)

    Full text: The design, calibration, radiation dosimetry and preliminary performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) are described. The system design was guided by Monte Carlo neutron and photon transport calculations performed using the MCNP-4C code. The facility utilizes a 555 GBq (15 Ci) Am-Be radionuclide neutron source positioned within a graphite collimator and appropriate shielding assembly. Prompt gamma rays produced by thermal neutron capture reactions within the animal are detected by a combination of a NaI(Tl) and a HPGe detectors positioned on either side of the sample, perpendicularly to the neutron beam. Small animal body nitrogen and hydrogen are determined by the NaI(Tl) detector by analysis of the 10.83 MeV and 2.22 MeV peaks, respectively, while calcium and chlorine are determined by the HPGe detector by analysis of the 6.42 MeV and 6.11 MeV peaks, respectively. Moreover, body potassium is determined independently by means of 40K measurement at a modified whole body counter facility. Appropriate corrections for animal body size and shape are applied. Mixed neutron and gamma radiation dosimetry was performed using a tissue-equivalent proportional counter. The facility described is a simple tool enabling us to perform in vivo analysis of the major body compartments of protein, bone mass, extra-cellular and intra-cellular space. It will be used to perform serial nutritional and metabolic studies in sets of small experimental animals under controlled conditions for an ethically accepted radiation dose and without the need to kill the animal. (author)

  3. Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

    Directory of Open Access Journals (Sweden)

    Panjeh Hamed

    2010-01-01

    Full Text Available The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In order to see the role of a detector shield, five kinds of the detector shield were used and finally the proper kind was introduced. Since the detector shield has an important contribution in the reduction of the undesirable and high rate gamma rays coming to the gamma ray detector, a good design of a proper shield enables the elimination of the unwanted events, such as a pulse pile-up. By improving the shielding design, discrete and distinguishable photoelectric peaks in the energy region of interest have been observed in the spectrum of prompt gamma rays.

  4. Neutron skin in Osmium isotopes

    International Nuclear Information System (INIS)

    Here we have made an attempt to calculate neutron skin thickness in rare earth even-even osmium isotopes. The selected isotopes ranges from 2-p to 2-n drip line. Neutron skin is an important feature of neutron rich nuclei. The ground state proton and neutron rms radii have been calculated using HFB approximation. A comparison of calculated radii have been done by using two different Skyrme parameterizations and two different basis

  5. Experimental evaluation of the neutrons flux of a irradiator with AmBe sources and its possibility of use in materials analysis

    International Nuclear Information System (INIS)

    This work had as a target to determine the irradiator thermal and over cadmium (epithermal and fast) neutrons flux , of the Nuclear Experimental Laboratory of the Nuclear Energy Center (CNEN) - IPEN, and the possibility of its use for Neutron Activation Analysis (NAA) by the absolute method. The neutrons flux quantification was performed indirectly by the gold naked and cadmium-covered foils activation technique. The neutrons flux was determined for two situations: with polyethylene block 5.0 cm thick and without the polyethylene block. The quantification of the elements present in the irradiated samples was obtained after the experimental determination of the incident neutrons flux in the irradiation position of the sample. Flux values along the irradiator axis were determined. Some materials were analyzed, presenting good agreement with reference values. (author)

  6. Isotopic neutron sources for neutron activation analysis

    International Nuclear Information System (INIS)

    This User's Manual is an attempt to provide for teaching and training purposes, a series of well thought out demonstrative experiments in neutron activation analysis based on the utilization of an isotopic neutron source. In some cases, these ideas can be applied to solve practical analytical problems. 19 refs, figs and tabs

  7. Neutron monitor calibration with 241AmBe(α, n), 252Cf , 252Cf+D2O and 238PuBe(α, n) used in dose evaluation near Linac

    International Nuclear Information System (INIS)

    The use of linear accelerators in Radiotherapy is becoming increasingly more common. From the Radiation Protection point of view, these instruments represent an advance relative to cobalt and caesium irradiators, mainly due to the absence of radioactive material. On the other hand, accelerators with energies over 10 MeV contaminate with neutrons the therapeutic beam. These neutrons are generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. Photo-neutrons can also interact with other materials, present in the treatment room, consequently modifying the initial spectrum and causing other types of interactions which privilege the gamma capture. In this way, the measurement of the photo-neutron spectrum can be necessary in a radiometric survey. The present work carries through measurements in a linear accelerator of 15 MeV using three neutron area monitors calibrated using four radioactive sources: three ISO reference sources, 241AmBe (α, n), 252Cf (f, n) and 252Cf+D2O, and a 238PuBe(α, n) source. As the three first sources, this last one was standardized in the LMNRI/IRD manganese bath system. Comparison and evaluation of the response of these instruments were thereby made, analyzing whether the reading of the detectors using standard sources is adequate. In conclusion, the analysis of the response of neutron area calibrated detectors enable the use of them in an environment containing medical linear accelerator. (author)

  8. Study of the geometrical configuration of a Set-Up for the purpose of analysing organic matter using neutron backscattering with an AM-BE source and a HE3 detector

    International Nuclear Information System (INIS)

    Neutron backscattering is a powerful technique to analyse organic matter and recently a set-up has been developed by our laboratory to determine bitumen content in asphalt concrete [1].This set-up is mainly composed of an Am-Be neutron source and a He-3 detector, the source being placed under the He-3 detector. In this work, we study two geometrical configurations, the first where the source is placed under the detector and the other one is when the source and the detector are side by side. The calibration curves for the determination of bitumen content in asphalt concrete, hydrogen and the ratio C/H are built for the two geometries and then compared in terms of sensitivity. Finally, some Algerian oil samples are analysed with these setups

  9. Neutron spectra and dosimetric features of isotopic neutron sources: a review

    International Nuclear Information System (INIS)

    A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of 24NaBe, 24NaD2O, 116InBe, 140LaBe, 238PuLi, 239PuBe, 241AmB, 241AmBe, 241AmF, 241AmLi, 242CmBe, 210PoBe, 226RaBe, 252Cf and 252Cf/D2O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

  10. Neutron spectra and dosimetric features of isotopic neutron sources: a review

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Martinez O, S. A., E-mail: fermineutron@yahoo.com [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte 39-115, 150003 Tunja, Boyaca (Colombia)

    2015-10-15

    A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of {sup 24}NaBe, {sup 24}NaD{sub 2}O, {sup 116}InBe, {sup 140}LaBe, {sup 238}PuLi, {sup 239}PuBe, {sup 241}AmB, {sup 241}AmBe, {sup 241}AmF, {sup 241}AmLi, {sup 242}CmBe, {sup 210}PoBe, {sup 226}RaBe, {sup 252}Cf and {sup 252}Cf/D{sub 2}O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

  11. Neutron monitor calibration with {sup 241}AmBe({alpha}, n), {sup 252}Cf , {sup 252C}f+D{sub 2}O and {sup 238}PuBe({alpha}, n) used in dose evaluation near Linac

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Ana Paula; Pereira, Walsan Wagner; Patrao, Karla Cristina de Souza; Fonseca, Evaldo Simoes da [Instituto de Radioprotecao e Dosimetria (IRD-CNEN/RJ), Rio de Janeiro, RJ (Brazil). Lab. de Neutrons], e-mail: asalgado@ird.gov.br

    2009-07-01

    The use of linear accelerators in Radiotherapy is becoming increasingly more common. From the Radiation Protection point of view, these instruments represent an advance relative to cobalt and caesium irradiators, mainly due to the absence of radioactive material. On the other hand, accelerators with energies over 10 MeV contaminate with neutrons the therapeutic beam. These neutrons are generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. Photo-neutrons can also interact with other materials, present in the treatment room, consequently modifying the initial spectrum and causing other types of interactions which privilege the gamma capture. In this way, the measurement of the photo-neutron spectrum can be necessary in a radiometric survey. The present work carries through measurements in a linear accelerator of 15 MeV using three neutron area monitors calibrated using four radioactive sources: three ISO reference sources, {sup 241}AmBe ({alpha}, n), {sup 252}Cf (f, n) and 252{sup C}f+D{sub 2}O, and a 238{sup P}uBe({alpha}, n) source. As the three first sources, this last one was standardized in the LMNRI/IRD manganese bath system. Comparison and evaluation of the response of these instruments were thereby made, analyzing whether the reading of the detectors using standard sources is adequate. In conclusion, the analysis of the response of neutron area calibrated detectors enable the use of them in an environment containing medical linear accelerator. (a0011uth.

  12. Spectrum of isotopic neutron sources inside concrete wall spherical cavities

    International Nuclear Information System (INIS)

    The neutron spectra of 252Cf/D2O, 140LaBe, 252Cf, 238Pu18O2, 241AmB, 241AmBe, 226RaBe and 239PuBe isotopic neutron sources due to room-return have been determined for various source-to-detector distances in concrete spherical cavities of different radius. Changes in the amount of thermal neutrons (E≤0.414eV) were analyzed to estimate, for each neutron source, the coefficient that relates the neutron source strength and room surface area with the thermal neutron fluence rates. The study was carried out using Monte Carlo methods for 200, 400, 500, 800, 1000, 1200 and 1500-cm-radius spherical cavity in vacuum; cavities are 100-cm-thick concrete. Point sources were located at the center of cavity and neutron spectra were calculated at several source-to-detector distances along the cavity radius. The thermal neutron contribution was thereby evaluated. From these calculations a weighted coefficient value that relates the thermal neutron fluence with the neutron source strength and the total inner area surface of the cavity was estimated to be 3.76±0.03

  13. Progress in transactinium isotope neutron data measurements

    International Nuclear Information System (INIS)

    This paper reviews the present state of the techniques used in different laboratories for neutron data measurements on transactinium isotopes, with emphasis on recent developments and possible improvements. The different domains investigated are: fission cross sections, prompt neutrons from fission, delayed neutrons from fission, prompt fission neutron spectrum, prompt fission gamma-rays, (n,xn) reactions, capture cross sections and neutron scattering

  14. Neutron spectra produced by moderating an isotopic neutron source

    International Nuclear Information System (INIS)

    A Monte Carlo study has been carried out to determine the neutron spectra produced by an isotopic neutron source inserted in moderating media. Most devices used for radiation protection have a response strongly dependent on neutron energy. ISO recommends several neutron sources and monoenergetic neutron radiations, but actual working situations have broad spectral neutron distributions extending from thermal to MeV energies, for instance, near nuclear power plants, medical applications accelerators and cosmic neutrons. To improve the evaluation of the dosimetric quantities, is recommended to calibrate the radiation protection devices in neutron spectra which are nearly like those met in practice. In order to complete the range of neutron calibrating sources, it seems useful to develop several wide spectral distributions representative of typical spectra down to thermal energies. The aim of this investigation was to use an isotopic neutron source in different moderating media to reproduce some of the neutron fields found in practice. MCNP code has been used during calculations, in these a 239PuBe neutron source was inserted in H2O, D2O and polyethylene moderators. Moderators were modeled as spheres and cylinders of different sizes. In the case of cylindrical geometry the anisotropy of resulting neutron spectra was calculated from 0 to 2. From neutron spectra dosimetric features were calculated. MCNP calculations were validated by measuring the neutron spectra of a 239PuBe neutron source inserted in a H2O cylindrical moderator. The measurements were carried out with a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. From the measurements the neutron spectrum was unfolded using the BUNKIUT code and the UTA4 response matrix. Some of the moderators with the source produce a neutron spectrum close to spectra found in actual applications, then can be used during the calibration of radiation protection devices

  15. Study of neutron-deficient Sn isotopes

    International Nuclear Information System (INIS)

    The formation of neutron deficient nuclei by heavy ion reactions is investigated. The experimental technique is presented, and the results obtained concerning Sn et In isotopes reported: first excited states of 106Sn, high spin states in 107Sn and 107In; Yrast levels of 106Sn, 107Sn, 108Sn; study of neutron deficient Sn and In isotopes formed by the desintegration of the compound nucleus 112Xe. All these results are discussed

  16. Securing the future of medical isotopes and neutron science in Canada: the Canadian Neutron Source (CNS)

    International Nuclear Information System (INIS)

    This presentation discusses establishment of the Canadian Neutron Source (CNS) that could be utilized for production of medical isotopes and neutron science in Canada. The Canadian Neutron Source would be 20 MWth research reactor optimized for delivery of medical isotopes and neutron beams for neutron science to serve both industry and the public sector. Employing existing reactor and isotope technology minimizes the risk and schedule. Neutron beams could be used in materials science research, biomedical research as well as imaging.

  17. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  18. Laser Spectroscopy of neutron deficient Sn isotopes

    CERN Multimedia

    We propose to study the ground state properties of neutron-deficient tin isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The tin isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

  19. Radiochemical studies of neutron deficient actinide isotopes

    International Nuclear Information System (INIS)

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, 242Bk, was produced with a cross-section of approximately 10 μb in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, αxn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,αxn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z1 + Z2 = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,αxn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of 228Pu, 230Pu, 232Cm, or 238Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes

  20. Radiochemical studies of neutron deficient actinide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.E.

    1978-04-01

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, /sup 242/Bk, was produced with a cross-section of approximately 10 ..mu..b in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, ..cap alpha..xn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,..cap alpha..xn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z/sub 1/ + Z/sub 2/ = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,..cap alpha..xn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of /sup 228/Pu, /sup 230/Pu, /sup 232/Cm, or /sup 238/Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes.

  1. Neutron capture by the chromium isotopes

    International Nuclear Information System (INIS)

    Capture cross sections of the chromium isotopes have been measured at neutron energies up to 350 keV using the capture cross section facility at the 40 m station of the Oak Ridge Electron Linear Accelerator. Parameters have been derived for 180 resonances. A moderate correlation [rho(gamma-n-0,gamma-gamma) approximately 0.45] is observed between reduced neutron widths and radiative widths for s-wave resonances. Calculations of valence widths show that valence capture can only account for the correlated component of the observed radiative widths. An additional mechanism such as a 2p-1h doorway state must therefore be occurring to explain the uncorrelated component. (author)

  2. Particles in classically forbidden area, neutron skin and halo, and pure neutron matter in Ca isotopes

    OpenAIRE

    Im, Soojae; Meng, J

    2000-01-01

    The nucleon density distributions and the thickness of pure neutron matter in Ca isotopes were systematically studied using the Skyrme-Hartree-Fock model (SHF) from the $\\beta$-stability line to the neutron drip-line. The pure neutron matter, related with the neutron skin or halo, was shown to depend not only on the Fermi levels of the neutrons but also on the orbital angular momentum of the valence neutrons. New definitions for the thickness of pure neutron matter are proposed.

  3. Characterization of a Sealed Americium-Beryllium (AmBe) Source by Inductively Coupled Plasma Mass Spectrometry

    International Nuclear Information System (INIS)

    Two Americium-Beryllium neutron sources were dismantled, sampled (sub-sampled) and analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Characteristics such as 'age' since purification, actinide content, trace metal content and inter and intra source composition were determined. The 'age' since purification of the two sources was determined to be 25.0 and 25.4 years, respectively. The systematic errors in the 'age' determination were ± 4 % 2s. The amount and isotopic composition of U and Pu varied substantially between the sub-samples of Source 2 (n=8). This may be due to the physical means of sub-sampling or the way the source was manufactured. Source 1 was much more consistent in terms of content and isotopic composition (n=3 sub-samples). The Be-Am ratio varied greatly between the two sources. Source 1 had an Am-Be ratio of 6.3 ± 52 % (1s). Source 2 had an Am-Be ratio of 9.81 ± 3.5 % (1s). In addition, the trace element content between the samples varied greatly. Significant differences were determined between Source 1 and 2 for Sc, Sr, Y, Zr, Mo, Ba and W.

  4. Thermal neutron capture cross sections of tellurium isotopes

    International Nuclear Information System (INIS)

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given

  5. Thermal neutron capture cross sections of tellurium isotopes

    International Nuclear Information System (INIS)

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te,124Te,125Te,126Te,128Te, and 130Te are reported. These values are based on a combination of newly determined partial γ-ray cross sections obtained from experiments on targets contained natural Te and γ intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given

  6. Thermal neutron capture cross sections of tellurium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tomandl, I.; Honzatko, J.; von Egidy, T.; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.

    2004-03-01

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given.

  7. Detection limits of pollutants in water for PGNAA using Am Be source

    Science.gov (United States)

    Khelifi, R.; Amokrane, A.; Bode, P.

    2007-09-01

    A basic PGNAA facility with an Am-Be neutron source is described to analyze the pollutants in water. The properties of neutron flux were determined by MCNP calculations. In order to determine the efficiency curve of a HPGe detector, the prompt-gamma rays from chlorine were used and an exponential curve was fitted. The detection limits for typical water sample are also estimated using the statistical fluctuations of the background level in the areas of recorded the prompt-gamma spectrum.

  8. Detection limits of pollutants in water for PGNAA using Am-Be source

    Energy Technology Data Exchange (ETDEWEB)

    Khelifi, R. [Departement de Physique, Universite Saad Dahlab, BP: 270, Blida (Algeria)], E-mail: r_khelifi@yahoo.com; Amokrane, A. [Faculte de Physique, USTHB, Bab Ezzouar, Alger (Algeria); Bode, P. [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB (Netherlands)

    2007-09-15

    A basic PGNAA facility with an Am-Be neutron source is described to analyze the pollutants in water. The properties of neutron flux were determined by MCNP calculations. In order to determine the efficiency curve of a HPGe detector, the prompt-gamma rays from chlorine were used and an exponential curve was fitted. The detection limits for typical water sample are also estimated using the statistical fluctuations of the background level in the areas of recorded the prompt-gamma spectrum.

  9. Uses of isotopic neutron sources in elemental analysis applications

    International Nuclear Information System (INIS)

    The extensive development and applications on the uses of isotopic neutron in the field of elemental analysis of complex samples are largely occurred within the past 30 years. Such sources are used extensively to measure instantaneously, simultaneously and nondestructively, the major, minor and trace elements in different materials. The low residual activity, bulk sample analysis and high accuracy for short lived elements are improved. Also, the portable isotopic neutron sources, offer a wide range of industrial and field applications. In this talk, a review on the theoretical basis and design considerations of different facilities using several isotopic neutron sources for elemental analysis of different materials is given

  10. Canadian Neutron Source (CNS): a research reactor solution for medical isotopes and neutrons for science

    International Nuclear Information System (INIS)

    This presentation describes a dual purpose research facility at the University of Saskatchewan for Canada for the production of medical isotopes and neutrons for scientific research. The proposed research reactor is intended to supply most of Canada's medical isotope requirements and provide a neutron source for Canada's research community. Scientific research would include materials research, biomedical research and imaging.

  11. Neutron capture reactions on Lu isotopes at DANCE

    International Nuclear Information System (INIS)

    The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for the 175Lu and 176Lu isotopes with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natural lutetium foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured. (authors)

  12. Neutron Capture Reactions on lu Isotopes at Dance

    Science.gov (United States)

    Roig, O.; Meot, V.; Daugas, J.-M.; Morel, P.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Wouters, J. M.

    2013-03-01

    The DANCE1 (Detector for Advanced Neutron Capture Experiments) array at LANSCE spallation neutron source in Los Alamos has been used to obtain the neutron radiative capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process.2,3 Three targets were used to perform these measurements. One was natural Lu foil of 31 mg/cm2 and the other two were isotope-enriched targets of 175Lu and 176Lu. Firstly, the cross sections were obtained by normalizing yield to a well-known cross section at the thermal neutron energy. Now, we want to obtain absolute cross sections of radiative capture through a precise neutron flux determination, an accurate target mass measurement and an efficiency determination of the DANCE array.

  13. Spectrometry and dosimetry of isotopic sources of neutrons by means of artificial neural networks

    International Nuclear Information System (INIS)

    The artificial neural networks technology has been applied to reconstruct the neutrons spectra of two isotopic sources: 252Cf, and 241Am-Be. Also, this technology has been applied to obtain the effective dose, E, and the personal dose equivalents, Hp(10) and environmental, H *(10). To obtain the spectra and the doses only were used the count rates produced in a Bonner Spheres spectrometer with a scintillator of 6LiI(Eu) of 0.4 φ x 0.4 cm2. The equivalent environmental dose and the spectra of the sources were also obtained by means of the reconstruction code BUNKIUT. When comparing the results obtained by means of both procedures it was found that they are consistent. (Author)

  14. Shell Model Description of Neutron-Deficient Sn Isotopes

    Institute of Scientific and Technical Information of China (English)

    Erdal Dikmen

    2009-01-01

    The shell model calculations in the sdgh major shell for the neutron-deficient 106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The single-shell states and the corresponding matrix elements needed for describing Sn isotopes are reconstructed to calculate the coefficient of fractional parantage by reducing the calculation requirements. This reconstruction allows us to do the shell model calculations of the neutron deficient Sn isotopes in very reasonable time. The results are compared to the recent high-resolution experimental data and found to be in good agreement with experiments.

  15. Neutron capture reactions on Lu isotopes at DANCE

    CERN Document Server

    Roig, O

    2010-01-01

    The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natLu foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured.

  16. Production of Medical isotope Technecium-99 from DT Fusion neutrons

    Science.gov (United States)

    Boguski, John; Gentile, Charles; Ascione, George

    2011-10-01

    High energy neutrons produced in DT fusion reactors have a secondary application for use in the synthesis of valuable man-made isotopes utilized in industry today. One such isotope is metastable Technecium-99 (Tc99m), a low energy gamma emitter used in ~ 85% of all medical imaging diagnostics. Tc99m is created through beta decay of Molybdenum-99 (Mo99), which itself has only a 66 hour half-life and must be created from a neutron capture by the widely available and stable isotope Molydenum-98. Current worldwide production of Tc99m occurs in just five locations and relies on obtaining the fission byproduct Mo99 from highly enriched Uranium reactors. A Tc99m generator using DT fusion neutrons, however, could potentially be operated at individual hospitals and medical facilities without the use of any fissile material. The neutron interaction of the DT neutrons with Molybdenum in a potential device geometry was modeled using Monte Carlo neutron transport code MCNP. Trial experiments were also performed to test the viability of using DT neutrons to create ample quantities of Tc99m. Modeling and test results will follow.

  17. Fission decay properties of ultra neutron-rich uranium isotopes

    Indian Academy of Sciences (India)

    L Satpathy; S K Patra; R K Choudhury

    2008-01-01

    The fission decay of highly neutron-rich uranium isotopes is investigated which shows interesting new features in the barrier properties and neutron emission characteristics in the fission process. 233U and 235U are the nuclei in the actinide region in the beta stability valley which are thermally fissile and have been mainly used in reactors for power generation. The possibility of occurrence of thermally fissile members in the chain of neutron-rich uranium isotopes is examined here. The neutron number = 162 or 164 has been predicted to be magic in numerous theoretical studies carried out over the years. The series of uranium isotopes around it with = 154-172 are identified to be thermally fissile on the basis of the fission barrier and neutron separation energy systematics; a manifestation of the close shell nature of = 162 (or 164). We consider here the thermal neutron fission of a typical representative 249U nucleus in the highly neutron-rich region. Semiempirical study of fission barrier height and width shows that 250U nucleus is stable against spontaneous fission due to increase in barrier width arising out of excess neutrons. On the basis of the calculation of the probability of fragment mass yields and the microscopic study in relativistic mean field theory, this nucleus is shown to undergo exotic decay mode of thermal neutron fission (multi-fragmentation fission) whereby a number of prompt scission neutrons are expected to be simultaneously released along with the two heavy fission fragments. Such properties will have important implications in stellar evolution involving -process nucleosynthesis.

  18. Radio-isotopic neutron sources for industrial applications and basic research

    International Nuclear Information System (INIS)

    CNIF2 is an irradiation facility based on an Am-Be (b, n) source with present activity of about 175 GBq results in a neutron yield of about 1.04*107 n/s. The facility provides fast and epi-thermal neutrons as well. The aim of the present work is to develop methods able to use neutron activation analysis to estimate the hydrogen content in bulk samples through neutron reflection and transmission processes.

  19. Octupole strength in the neutron-rich calcium isotopes

    CERN Document Server

    Riley, L A; Agiorgousis, M L; Baugher, T R; Bazin, D; Bowry, M; Cottle, P D; DeVone, F G; Gade, A; Glowacki, M T; Gregory, S D; Haldeman, E B; Kemper, K W; Lunderberg, E; Noji, S; Recchia, F; Sadler, B V; Scott, M; Weisshaar, D; Zegers, R G T

    2016-01-01

    Low-lying excited states of the neutron-rich calcium isotopes $^{48-52}$Ca have been studied via $\\gamma$-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA $\\gamma$-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.

  20. Exotic fission properties of highly neutron-rich Uranium isotopes

    OpenAIRE

    Satpathy, L.; Patra, S.K.; Choudhury, R. K.

    2007-01-01

    The series of Uranium isotopes with $N=154 \\sim 172$ around the magic number N=162/164 are identified to be thermally fissile. The thermal neutron fission of a typical representative $^{249}$U of this region amenable to synthesis in the radioactive ion beam facilities is considered here. Semiempirical study of fission barrier height and width shows this nucleus to be infinitely stable against spontaneous fission due to increase in barrier width arising out of excess neutrons. Calculation of p...

  1. Direct measurements of neutron capture on radioactive isotopes

    CERN Document Server

    Couture, A

    2009-01-01

    We simulated the response of a 4p calorimetric g-detector array to decays of radioactive isotopes on the s-process path. The GEANT 3.21 simulation package was used. The main table contains estimates on the maximum sample size and required neutron flux based on the latest available neutron capture cross section at 30 keV. The results are intended to be used to estimate the feasibility of neutron capture measurements with 4p arrays using the time of flight technique.

  2. Neutron Capture Radiography: Neutron Capture Radiography:a technique for isotopic labelling and analytical imaging with a few stable isotopes

    OpenAIRE

    Michel Thellier; Camille Ripoll

    2006-01-01

    NCR (neutron capture radiography) may be used successfully for the imaging of one of the stable isotopes of a few chemical elements (especially 6Li and 10B, possibly also 14N, 17O, and others) and for labelling experiments using these stable isotopes. Other physical techniques compete with NCR. However, NCR can remain extremely useful in a certain number of cases, because it is usually more easily done and is less expensive than the other techniques.

  3. Neutron Capture Radiography: Neutron Capture Radiography:a technique for isotopic labelling and analytical imaging with a few stable isotopes

    Directory of Open Access Journals (Sweden)

    Michel Thellier

    2006-01-01

    Full Text Available NCR (neutron capture radiography may be used successfully for the imaging of one of the stable isotopes of a few chemical elements (especially 6Li and 10B, possibly also 14N, 17O, and others and for labelling experiments using these stable isotopes. Other physical techniques compete with NCR. However, NCR can remain extremely useful in a certain number of cases, because it is usually more easily done and is less expensive than the other techniques.

  4. Calculation of prompt neutron spectra for curium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1997-03-01

    With the aim of checking the existing evaluations contained in JENDL-3.2 and providing new evaluations based on a methodology proposed by the author, a series of calculations of prompt neutron spectra have been undertaken for curium isotopes. Some of the evaluations in JENDL-3.2 was found to be unphysically hard and should be revised. (author)

  5. New neutron-deficient isotopes from 78Kr fragmentation

    Science.gov (United States)

    Blank, B.; Goigoux, T.; Ascher, P.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kurtukian Nieto, T.; Magron, C.; Agramunt, J.; Algora, A.; Guadilla, V.; Montaner-Piza, A.; Morales, A. I.; Orrigo, S. E. A.; Rubio, B.; Ahn, D. S.; Doornenbal, P.; Fukuda, N.; Inabe, N.; Kiss, G.; Kubo, T.; Kubono, S.; Nishimura, S.; Phong, V. H.; Sakurai, H.; Shimizu, Y.; Söderström, P.-A.; Sumikama, T.; Suzuki, H.; Takeda, H.; Wu, J.; Fujita, Y.; Tanaka, M.; Gelletly, W.; Aguilera, P.; Molina, F.; Diel, F.; Lubos, D.; de Angelis, G.; Napoli, D.; Borcea, C.; Boso, A.; Cakirli, R. B.; Ganioglu, E.; Chiba, J.; Nishimura, D.; Oikawa, H.; Takei, Y.; Yagi, S.; Wimmer, K.; de France, G.; Go, S.

    2016-06-01

    In an experiment with the RIKEN projectile fragment separator called BigRIPS at the RIKEN Nishina Center, the fragmentation of a 78Kr beam allowed the observation of new neutron-deficient isotopes at the proton drip line. Clean identification spectra could be produced and 63Se,67Kr, and 68Kr were identified for the first time. In addition, 59Ge was also observed. Three of these isotopes, 59Ge,63Se, and 67Kr, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes 58Ge,62Se, and 66Kr were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic isotopes. These measurements confirm the trend already observed that the empirical parametrization of fragmentation cross sections, EPAX, significantly overestimates experimental cross sections in this mass region.

  6. Neutron capture measurements on Tl-isotopes at Dance

    International Nuclear Information System (INIS)

    The thallium isotopes play an important role in the s-process nucleosynthesis at the s-process endpoint. Furthermore, 204Tl is one of few branch point isotopes in the endpoint region. The understanding of branch point isotopes provides modeling constraints on the temperatures and neutron densities during which the process takes place. The production of s-only 204Pb is controlled almost entirely by 204Tl. Measurements of the capture cross-sections of the stable Tl isotopes have recently been made using the DANCE 4π array at LANSCE. This provides needed resonance information in the region as well as preparing the way for measurements of as yet unmeasured capture cross-section of the unstable 204Tl. (authors)

  7. Neutron capture measurements on Tl-isotopes at Dance

    Energy Technology Data Exchange (ETDEWEB)

    Couture, A.; Reifarth, R.; Bredeweg, T.A.; Haight, R.C.; Jandel, M.; Mertz, A.F.; O' Donnell, J.M.; Rundberg, R.S.; Ullmann, J.L.; Viera, D.J.; Wouters, J.M. [Los Alamos National Laboratory, NM (United States); Baker, J.D. [Idaho National Laboratory, Idaho Falls, ID (United States)

    2008-07-01

    The thallium isotopes play an important role in the s-process nucleosynthesis at the s-process endpoint. Furthermore, {sup 204}Tl is one of few branch point isotopes in the endpoint region. The understanding of branch point isotopes provides modeling constraints on the temperatures and neutron densities during which the process takes place. The production of s-only {sup 204}Pb is controlled almost entirely by {sup 204}Tl. Measurements of the capture cross-sections of the stable Tl isotopes have recently been made using the DANCE 4{pi} array at LANSCE. This provides needed resonance information in the region as well as preparing the way for measurements of as yet unmeasured capture cross-section of the unstable {sup 204}Tl. (authors)

  8. New neutron-deficient isotopes from $^{78}$Kr fragmentation

    CERN Document Server

    Blank, B; Ascher, P; Gerbaux, M; Giovinazzo, J; Grevy, S; Nieto, T Kurtukian; Magron, C; Agramunt, J; Algora, A; Guadilla, V; Montaner-Piza, A; Morales, A I; Orrigo, S E A; Rubio, B; Ahn, D S; Doornenbal, P; Fukuda, N; Inabe, N; Kiss, G; Kubo, T; Kubono, S; Nishimura, S; Phong, V H; Sakurai, H; Shimizu, Y; Soderstrom, P -A; Sumikama, T; Suzuki, H; Takeda, H; Wu, J; Fujita, Y; Tanaka, M; Gelletly, W; Aguilera, P; Molina, F; Diel, F; Lubos, D; de Angelis, G; Napoli, D; Borcea, C; Boso, A; Cakirli, R B; Ganioglu, E; Chiba, J; Nishimura, D; Oikawa, H; Takei, Y; Yagi, S; Wimmer, K; de France, G; Go, S

    2016-01-01

    In an experiment with the BigRIPS separator at the RIKEN Nishina Center, the fragmentation of a $^{78}$Kr beam allowed the observation of new neutron-deficient isotopes at the proton drip-line. Clean identification spectra could be produced and $^{63}$Se, $^{67}$Kr, and $^{68}$Kr were identified for the first time. In addition, $^{59}$Ge was also observed. Three of these isotopes, $^{59}$Ge, $^{63}$Se, and $^{67}$Kr, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes $^{58}$Ge, $^{62}$Se, and $^{66}$Kr were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic isotopes. These measurements confirm the trend already observed that the empirical parameterization of fragmentation cross sections, EPAX, significantly overestimates experimental cross sections in this mass region.

  9. Quadrupole collectivity in neutron-rich Cd isotopes

    International Nuclear Information System (INIS)

    The proximity to the closed shells at Z = 50 and N = 82 makes the neutron-rich Cd isotopes a perfect test case for nuclear theories. The energy of the first excited 2+-state in the even 122-128 shows an irregular behaviour as the Cd isotopes exhibit only a slight increase for 122Cd to 126Cd and even a decrease from 126Cd to 128Cd. This anomaly can so far not be reproduced by shell model calculations. Only beyond mean field calculations with a resultant prolate deformation are capable to describe this anomalous behaviour. In order to gain more information about the neutron-rich Cd isotopes a Coulomb excitation experiment was performed with MINIBALL at REX-ISOLDE, CERN. The extracted transition strengths B (E2,0+gs → 2+1) for 122,124,126,128Cd agree with beyond mean field calculations. The spectroscopic quadrupole moments Qs (2+1) are compared with measurements on odd neutron-rich Cd isotopes

  10. Spectrometry and dosimetry of isotopic sources of neutrons by means of artificial neural networks; Espectrometria y dosimetria de fuentes isotopicas de neutrones mediante redes neuronales artificiales

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Ortiz R, J. M.; Hernandez D, V. M; Martinez B, M. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, C/Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain); Barquero, R., E-mail: fermineutron@yahoo.co [Hospital del Rio Hortega, C/Dulzaina No. 2, 47012 Valladolid (Spain)

    2010-09-15

    The artificial neural networks technology has been applied to reconstruct the neutrons spectra of two isotopic sources: {sup 252}Cf, and {sup 241}Am-Be. Also, this technology has been applied to obtain the effective dose, E, and the personal dose equivalents, Hp(10) and environmental, H *(10). To obtain the spectra and the doses only were used the count rates produced in a Bonner Spheres spectrometer with a scintillator of {sup 6}LiI(Eu) of 0.4 {phi} x 0.4 cm{sup 2}. The equivalent environmental dose and the spectra of the sources were also obtained by means of the reconstruction code BUNKIUT. When comparing the results obtained by means of both procedures it was found that they are consistent. (Author)

  11. Medical Isotope Production Analyses In KIPT Neutron Source Facility

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States); Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    Medical isotope production analyses in Kharkov Institute of Physics and Technology (KIPT) neutron source facility were performed to include the details of the irradiation cassette and the self-shielding effect. An updated detailed model of the facility was used for the analyses. The facility consists of an accelerator-driven system (ADS), which has a subcritical assembly using low-enriched uranium fuel elements with a beryllium-graphite reflector. The beryllium assemblies of the reflector have the same outer geometry as the fuel elements, which permits loading the subcritical assembly with different number of fuel elements without impacting the reflector performance. The subcritical assembly is driven by an external neutron source generated from the interaction of 100-kW electron beam with a tungsten target. The facility construction was completed at the end of 2015, and it is planned to start the operation during the year of 2016. It is the first ADS in the world, which has a coolant system for removing the generated fission power. Argonne National Laboratory has developed the design concept and performed extensive design analyses for the facility including its utilization for the production of different radioactive medical isotopes. 99Mo is the parent isotope of 99mTc, which is the most commonly used medical radioactive isotope. Detailed analyses were performed to define the optimal sample irradiation location and the generated activity, for several radioactive medical isotopes, as a function of the irradiation time.

  12. Medical Isotope Production Analyses In KIPT Neutron Source Facility

    International Nuclear Information System (INIS)

    Medical isotope production analyses in Kharkov Institute of Physics and Technology (KIPT) neutron source facility were performed to include the details of the irradiation cassette and the self-shielding effect. An updated detailed model of the facility was used for the analyses. The facility consists of an accelerator-driven system (ADS), which has a subcritical assembly using low-enriched uranium fuel elements with a beryllium-graphite reflector. The beryllium assemblies of the reflector have the same outer geometry as the fuel elements, which permits loading the subcritical assembly with different number of fuel elements without impacting the reflector performance. The subcritical assembly is driven by an external neutron source generated from the interaction of 100-kW electron beam with a tungsten target. The facility construction was completed at the end of 2015, and it is planned to start the operation during the year of 2016. It is the first ADS in the world, which has a coolant system for removing the generated fission power. Argonne National Laboratory has developed the design concept and performed extensive design analyses for the facility including its utilization for the production of different radioactive medical isotopes. 99Mo is the parent isotope of 99mTc, which is the most commonly used medical radioactive isotope. Detailed analyses were performed to define the optimal sample irradiation location and the generated activity, for several radioactive medical isotopes, as a function of the irradiation time.

  13. Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

    CERN Document Server

    Flanagan, K T; Ruiz, R F Garcia; Budincevic, I; Procter, T J; Fedosseev, V N; Lynch, K M; Cocolios, T E; Marsh, B A; Neyens, G; Strashnov, I; Stroke, H H; Rossel, R E; Heylen, H; Billowes, J; Rothe, S; Bissell, M L; Wendt, K D A; de Groote, R P; De Schepper, S

    2013-01-01

    The magnetic moments and isotope shifts of the neutron-deficient francium isotopes Fr202-205 were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1\\% was measured for Fr-202. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to Fr-205, with a departure observed in Fr-203 (N = 116).

  14. Level structures of neutron-rich Xe isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    The level structures of neutron-rich Xe isotopes were determined by observing prompt gamma-ray coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 248}Cm, in the form of {sup 248}Cm-KCl pellet, was placed inside Eurogam array which consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. Transitions in Xe isotopes were identified by the appearance of new peaks in the {gamma}-ray spectra obtained by gating on the gamma peaks of the complementary Mo fragments.

  15. Properties of neutron-rich Ni isotopes investigated at LAND

    International Nuclear Information System (INIS)

    A kinematical complete measurement of reactions with relativistic beams of unstable 68-72Ni isotopes has been performed at the LAND reaction setup at GSI. Different targets (C,CH2, Pb) have been measured in order to investigate different types of reactions including heavy-ion induced electromagnetic excitation, nuclear neutron removal reactions, as well as quasi-free knockout reactions. From the differential cross section for electromagnetic excitation the dipole-strength distribution in the continuum is extracted in order to explore the low-lying pygmy dipole mode. The shell-structure of the neutron-rich Ni isotopes around the semi-magic 68Ni is studied using nucleon-removal reactions. A first attempt has been undertaken to measure (p,2p) knockout reactions using a CH2 target. Selected first results are presented

  16. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    A Ansari; H L Yadav; M Kaushik; U R Jakhar

    2003-06-01

    In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number = 166 and 168, we have made theoretical investigations on the structure of high spin states of 164-170Dy isotopes in the cranked Hartree–Fock–Bogoliubov (CHFB) theory employing a pairing+quadrupole+hexadecapole model interaction. With the increase of neutron number the rotation alignment of the proton orbitals dominates the structure at high spins, which is clearly reflected in the spin dependence of the rotational g-factors. A particularly striking feature is the difference in the spin-dependent properties of 166Dy as compared to that of 164Dy.

  17. The bound coherent neutron scattering lengths of the oxygen isotopes

    Science.gov (United States)

    Fischer, Henry E.; Simonson, J. Mike; Neuefeind, Jörg C.; Lemmel, Hartmut; Rauch, Helmut; Zeidler, Anita; Salmon, Philip S.

    2012-12-01

    The technique of neutron interferometry was used to measure the bound coherent neutron scattering length bcoh of the oxygen isotopes 17O and 18O. From the measured difference in optical path between two water samples, either H217O or H218O versus H2natO, where nat denotes the natural isotopic composition, we obtain bcoh,17O = 5.867(4) fm and bcoh,18O = 6.009(5) fm, based on the accurately known value of bcoh,natO = 5.805(4) fm which is equal to bcoh,16O within the experimental uncertainty. Our results for bcoh,17O and bcoh,18O differ appreciably from the standard tabulated values of 5.6(5) fm and 5.84(7) fm, respectively. In particular, our measured scattering-length contrast of 0.204(3) fm between 18O and natO is nearly a factor of 6 greater than the tabulated value, which renders feasible neutron diffraction experiments using 18O isotope substitution and thereby offers new possibilities for measuring the partial structure factors of oxygen-containing compounds, such as water.

  18. Unexpectedly large charge radii of neutron-rich calcium isotopes

    Science.gov (United States)

    Garcia Ruiz, R. F.; Bissell, M. L.; Blaum, K.; Ekström, A.; Frömmgen, N.; Hagen, G.; Hammen, M.; Hebeler, K.; Holt, J. D.; Jansen, G. R.; Kowalska, M.; Kreim, K.; Nazarewicz, W.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Papenbrock, T.; Papuga, J.; Schwenk, A.; Simonis, J.; Wendt, K. A.; Yordanov, D. T.

    2016-06-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain `magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-rich atomic nuclei.

  19. Unexpectedly large charge radii of neutron-rich calcium isotopes

    CERN Document Server

    Garcia Ruiz, R F; Blaum, K; Ekström, A; Frömmgen, N; Hagen, G; Hammen, M; Hebeler, K; Holt, J D; Jansen, G R; Kowalska, M; Kreim, K; Nazarewicz, W; Neugart, R; Neyens, G; Nörtershäuser, W; Papenbrock, T; Papuga, J; Schwenk, A; Simonis, J; Wendt, K A; Yordanov, D T

    2016-01-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain ‘magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-...

  20. Laser spectroscopy of neutron deficient gold and platinum isotopes

    International Nuclear Information System (INIS)

    A new method for on-line laser spectroscopy of radioactive atoms based on the resonant ionization spectroscopy of laser-desorbed radioactive samples has been devised. An experimental setup has been installed on-line at the ISOCELE mass separator in Orsay (France) and experiments have been performed on the region of transitional nuclei around Z=79. Isotopic shift measurements on four new isotopes 194Au, 196Au, 198Au, 199Au have been performed on gold and results on the neutron deficient isotopes down to 186 Au have been obtained confirming the nuclear ground-state shape transition from oblate to prolate between 187Au and 186Au. The first isotopic shift measurements on radioactive platinum isotopes have been obtained on 186Pt, 188Pt, 189Pt. Indications of a shape transition have been observed between 186Pt and 188Pt. The extracted experimental changes in mean square charge radii δ 2 > A,A' along isotopic chains are compared to self-consistent Hartree-Fock plus BCS calculations

  1. Neutron-spectroscopic strength in Ru isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, J.L.M.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B. (Instituto de Fisica da Univrsidade de Sao Paulo, Sao Paulo (Brazil))

    1994-08-01

    A systematic, high resolution (6--8 keV) study of ([ital d],[ital t]) reactions on [sup 100,102,104]Ru is reported. Spectroscopic factors were extracted by comparison of experimental angular distributions with distorted wave Born approximation predictions. All of the information for [sup 99]Ru and, for excitation energies above 0.9 MeV, for [sup 103]Ru is new. Most of the strength expected for the 50--82 neutron shell was found. The strength distributions are discussed, also in comparison with the corresponding stripping reactions. Special attention is focused on extremely low and relatively intense [ital l]=3 excitations and on the [ital l]=4 transfer pattern observed.

  2. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    International Nuclear Information System (INIS)

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for 241Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for 243Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on 242mAm will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,γ) from (n,f) events. The first evidence of neutron capture on 242mAm in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  3. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    Energy Technology Data Exchange (ETDEWEB)

    Jandel, Marian [Los Alamos National Laboratory

    2008-01-01

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  4. Neutronics modeling of the High Flux Isotope Reactor using COMSOL

    International Nuclear Information System (INIS)

    Highlights: → Neutron flux distributions in HFIR were calculated with SCALE v6 and COMSOL v3.5. → Diffusion theory employed in COMSOL coefficient partial differential equation mode. → Two-group 2D flux distributions compare well to benchmarked 3D stochastic models. → Adaptive mesh refinement algorithm used to refine mesh and improve accuracy. → First step in a long-term project to upgrade research reactor analytical methods. - Abstract: The High Flux Isotope Reactor located at the Oak Ridge National Laboratory is a versatile 85 MWth research reactor with cold and thermal neutron scattering, materials irradiation, isotope production, and neutron activation analysis capabilities. HFIR staff members are currently in the process of updating the thermal hydraulic and reactor transient modeling methodologies. COMSOL Multiphysics has been adopted for the thermal hydraulic analyses and has proven to be a powerful finite-element-based simulation tool for solving multiple physics-based systems of partial and ordinary differential equations. Modeling reactor transients is a challenging task because of the coupling of neutronics, heat transfer, and hydrodynamics. This paper presents a preliminary COMSOL-based neutronics study performed by creating a two-dimensional, two-group, diffusion neutronics model of HFIR to study the spatially-dependent, beginning-of-cycle fast and thermal neutron fluxes. The 238-group ENDF/B-VII neutron cross section library and NEWT, a two-dimensional, discrete-ordinates neutron transport code within the SCALE 6 code package, were used to calculate the two-group neutron cross sections required to solve the diffusion equations. The two-group diffusion equations were implemented in the COMSOL coefficient form PDE application mode and were solved via eigenvalue analysis using a direct (PARDISO) linear system solver. A COMSOL-provided adaptive mesh refinement algorithm was used to increase the number of elements in areas of largest numerical

  5. Neutron-rich chromium isotope anomalies in supernova nanoparticles

    CERN Document Server

    Dauphas, Nicolas; Chen, James; Roskosz, Mathieu; Papanastassiou, Dimitri; Stodolna, Julien; Guan, Yunbin; Ma, Chi; Eiler, John

    2010-01-01

    Neutron-rich isotopes with masses near that of iron are produced in type Ia and II supernovae. Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of 54Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of supernovae, offering the opportunity to study the nucleosynthesis of iron-peak nuclei in ways that complement spectroscopic observations and can inform models of stellar evolution. However, despite almost two decades of extensive search, the carrier of 54Cr anomalies is still unknown, presumably because it is fine-grained and is chemically labile. Here we identify in the primitive meteorite Orgueil the carrier of 54Cr-anomalies as nanoparticles, most likely spinels that show large enrichments in 54Cr relative to solar composition (54Cr/52Cr ratio >3.6xsolar). Such large enrichments in 54Cr can only be produced in supernovae. The mineralogy of the gr...

  6. Neutron capture cross section on Lu isotopes at DANCE

    International Nuclear Information System (INIS)

    The DANCE (Detector for Advanced Neutron Capture Experiments) array at the LANSCE spallation neutron source in Los Alamos has been used to measure neutron capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the s-process nucleosynthesis. 175Lu is an important waiting-point in the s-process and 176Lu is a sensitive s-process thermometer. Three targets were used to perform these measurements. One was a natural Lu foil of 31 mg/cm2 and the other two were isotopically enriched targets of 175Lu (99.8%, ∼1 mg/cm2 electro-deposited on Ti) and 176Lu (99.9%, ∼1 mg/cm2 mass separator deposited on aluminized mylar). The data analysis is in progress. Preliminary cross sections have been obtained by normalizing the data to the known thermal cross section. A comparison of these data with recent experimental data of K. Wisshak et al. and the evaluated data of ENDF B-VII will be presented.

  7. Gamma Spectrum from Neutron Capture on Tungsten Isotopes

    International Nuclear Information System (INIS)

    An evaluation of thermal neutron capture on the stable tungsten isotopes is presented, with preliminary results for the compound systems 183,184,185,187W. The evaluation procedure compares the γ-ray cross-section data collected at the Budapest reactor, with Monte Carlo simulations of γ-ray emission following the thermal neutron-capture process. The statistical-decay code DICEBOX was used for the Monte Carlo simulations. The evaluation yields new gamma rays in 185W and the confirmation of spins in 187W, raising the number of levels below which the level schemes are considered complete, thus increasing the number of levels that can be used in neutron data libraries.

  8. Thermal Neutron Capture Cross Sections of The Palladium Isotopes

    International Nuclear Information System (INIS)

    We have measured precise thermal neutron capture γ-ray cross sections σγ for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF)[1]. Total radiative neutron capture cross-sections σ0 can be deduced from the sum of transition cross sections feeding the ground state of each isotope if the decay scheme is complete. The Palladium isotope decay schemes are incomplete, although transitions deexciting low-lying levels are known for each isotope. We have performed Monte Carlo simulations of the Palladium thermal neutron capture de-excitation schemes using the computer code DICEBOX [2]. This program generates a level scheme where levels below a critical energy Ecrit are taken from experiment, and those above Ecrit are calculated by a random discretization of an a priori known level density formula ρ(E, Jπ). Level de-excitation branching intensities are taken from experiment for levels below Ecrit and the capture state, or calculated for levels above Ecrit assuming an a priori photon strength function and applying allowed selection rules and a Porter-Thomas distribution of widths. The calculated feeding to levels below Ecrit can then be normalized to the measured cross section deexciting those levels to determine the total radiative neutron cross-section σ0. In this paper we have measured σ0[102Pd(n,γ)] = 0.9 ± 0.3 b, σ0[104Pd(n,γ)] = 0.61 ± 0.11 b, σ0[105Pd(n,γ)] = 21.1 ± 1.5 b, σ0[106Pd(n,γ)] = 0.36 ± 0.05 b, σ0[108Pd(n,γ)(0)] = 7.6 ± 0.6 b, σ0[108Pd(n,γ)(189)] = 0.185 ± 0.011 b, and σ0[110Pd(n,γ)] = 0.10 ± 0.03 b. We have also determined from our statistical calculations that the neutron capture state in 107Pd is best described as 2+(60%)+3+(40%). Agreement with literature values was excellent in most cases. We found significant discrepancies between our results for 102

  9. A new Am-Be PGNAA setup for element determination in aqueous solution.

    Science.gov (United States)

    Yongsheng, Ling; Wenbao, Jia; Daqian, Hei; Qing, Shan; Can, Cheng; Haojia, Zhang; Wenyu, Hou; Yanquan, He; Da, Chen

    2014-11-12

    A new prompt-gamma neutron activation analysis (PGNAA) setup has been designed for element determination in aqueous solution with a 300 mCi (241)Am-Be neutron source and a 4in.×3in. (diameter×height) BGO detector, uncooled. A polyethylene cylindrical sample container approximately 40cm in outer radius and 80cm in height was used. To reduce the neutron dose in the detector, a block of 5cm thickness Li2CO3 was placed between the source and the detector for separation, but no gamma-blocker was used. By adjusting the position of the detector and optimizing the geometrical conditions of the setup, the element detection limit with a low activity neutron source was further improved. This methodology was checked by simulations with chlorine, mercury and cadmium determination and by experiments with chlorine determination in aqueous samples. The results show a good linear relationship between chlorine concentration and the count of its characteristic peak, and the detection limit of chlorine can reach 41.7mg/L with a collection time of 3600s for each spectrum. Additionally, a linear relationship was identified between mercury concentration and the count of its characteristic peak, but for cadmium, a non-linear relationship was observed in the simulations. PMID:25464204

  10. Neutron scattering at the high-flux isotope reactor

    International Nuclear Information System (INIS)

    The title facilities offer the brightest source of neutrons in the national user program. Neutron scattering experiments probe the structure and dynamics of materials in unique and complementary ways as compared to x-ray scattering methods and provide fundamental data on materials of interest to solid state physicists, chemists, biologists, polymer scientists, colloid scientists, mineralogists, and metallurgists. Instrumentation at the High- Flux Isotope Reactor includes triple-axis spectrometers for inelastic scattering experiments, a single-crystal four diffractometer for crystal structural studies, a high-resolution powder diffractometer for nuclear and magnetic structure studies, a wide-angle diffractometer for dynamic powder studies and measurements of diffuse scattering in crystals, a small-angle neutron scattering (SANS) instrument used primarily to study structure-function relationships in polymers and biological macromolecules, a neutron reflectometer for studies of surface and thin-film structures, and residual stress instrumentation for determining macro- and micro-stresses in structural metals and ceramics. Research highlights of these areas will illustrate the current state of neutron science to study the physical properties of materials

  11. Study of neutron deficient iridium isotopes by using laser spectroscopy

    International Nuclear Information System (INIS)

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes 182-189Ir, 186Irm and stable isotopes 191,193Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d76s24F9/2 ground state and the 5d76s6p 6F11/2 excited state. Radioactive iridium isotopes were obtained from β+/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between 187Ir and 186Irg, accompanied by a sudden increase in deformation: from β2 ∼ 0,16 to β2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the π3/2+[402] orbital for the smaller deformations nuclei and with the π1/2-[541] orbital stemming from the h9/2 subshell for bigger deformations nuclei. (author)

  12. Isotopic yield distribution of neutron-rich fragment nuclei produced in thermal neutron induced fission

    International Nuclear Information System (INIS)

    Nuclear fission allows us to produce and study the properties of the nuclei with a higher neutron to proton ratio. Spectroscopic studies of such neutron-rich fragment nuclei provide direct information on the nuclear excited states. Such studies help to explore the new regions of nuclear deformations, and to extend the theoretical model(s) to regions which have hitherto been inaccessible. A lot of work has already been done on these set of nuclei by means of spontaneous fission of 252Cf and 248Cm sources, heavy-ion induced fusion-fission reactions, and also using deep-inelastic reactions. More recently, spectroscopic studies were performed using thermal neutron induced fission of 235U using CIRUS reactor facility. Here we report the yield distribution of the isotopes, produced in thermal neutron induced fission of 235U, using prompt γ-γ coincidence measurement technique

  13. NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

    Energy Technology Data Exchange (ETDEWEB)

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen' s Road, Bristol BS8 1RJ (United Kingdom); Russell, Sara, E-mail: r.steele@uclmail.net [Meteoritics and Cosmic mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2012-10-10

    We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61}, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the {sup 58}Ni/{sup 61}Ni internally normalized {sup 60}Ni/{sup 61}Ni, {sup 62}Ni/{sup 61}Ni, and {sup 64}Ni/{sup 61}Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61} relative to a typical sample precision of 0.03, 0.05, and 0.08 (2 s.e.), respectively. The carbonaceous chondrites show the largest positive anomalies, enstatite chondrites have approximately terrestrial ratios, though only EH match Earth's composition within uncertainty, and ordinary chondrites show negative anomalies. The meteorite data show a strong positive correlation between {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}, an extrapolation of which is within the error of the average of previous measurements of calcium-, aluminium-rich inclusions. Moreover, the slope of this bulk meteorite array is 3.003 {+-} 0.166 which is within the error of that expected for an anomaly solely on {sup 58}Ni. We also determined to high precision ({approx}10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}. These analyses show that 'absolute' ratios of {sup 58}Ni/{sup 61}Ni vary between these two samples whereas those of {sup 62}Ni/{sup 61}Ni and {sup 64}Ni/{sup 61}Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor {sup 58}Ni, and not correlated anomalies in the neutron-rich isotopes, {sup 62}Ni and {sup 64}Ni. This contrasts with previous inferences from mass-independent measurements of Ni and

  14. Monte Carlo optimization of sample dimensions of an 241Am Be source-based PGNAA setup for water rejects analysis

    Science.gov (United States)

    Idiri, Z.; Mazrou, H.; Beddek, S.; Amokrane, A.; Azbouche, A.

    2007-07-01

    The present paper describes the optimization of sample dimensions of a 241Am-Be neutron source-based Prompt gamma neutron activation analysis (PGNAA) setup devoted for in situ environmental water rejects analysis. The optimal dimensions have been achieved following extensive Monte Carlo neutron flux calculations using MCNP5 computer code. A validation process has been performed for the proposed preliminary setup with measurements of thermal neutron flux by activation technique of indium foils, bare and with cadmium covered sheet. Sensitive calculations were subsequently performed to simulate real conditions of in situ analysis by determining thermal neutron flux perturbations in samples according to chlorine and organic matter concentrations changes. The desired optimal sample dimensions were finally achieved once established constraints regarding neutron damage to semi-conductor gamma detector, pulse pile-up, dead time and radiation hazards were fully met.

  15. Thermonuclear neutron sources - a new isotope production technology

    International Nuclear Information System (INIS)

    With the successful detonation of the Hutch device, we have demonstrated the feasibility of a new isotope production technique. The exposure of a 238-U and 232-Th target to an extremely large neutron flux, 1.8 x 1025 neutrons/cm2, produced super-heavy nuclides up to 257-Fm by the multiple neutron capture process. Kilogram quantities of Hutch debris were recovered by a modification of standard drilling techniques. A semicontinuous batch process was used to concentrate approximately 1010 atoms of 257-Fm from approximately 50 kg of debris. Experience from the Hutch debris recovery efforts indicates that significant engineering advances in recovery techniques and subsequent cost reductions are possible. The demonstrated success of the device clearly justifies anengineering development program. Comparing debris recovery by underground mining operations with recovery using possible advances in drilling technology does not indicate an obvious cost advantage of one system over the other. Possible advances in mining technology could change this tentative conclusion. Any novel schemes for debris concentration that might be possible through an understanding of underground nuclear detonation phonomenology would also radically affect recovery and processing economics. A preliminary process engineering design of a large-scale (a few hundred to a few thousand kilograms) processing facility located at the Nevada Test Site will be discussed. Cost estimates for isotopes produced in this facility will be described. The effects of debris concentration, 'ore' beneficiation, and total debris processed on unit costs will be discussed. These preliminary estimates show that this new isotope 'production' scheme would be competitive with existing reactor facilities. (author)

  16. Isotopic composition and neutronics of the Okelobondo natural reactor

    Science.gov (United States)

    Palenik, Christopher Samuel

    The Oklo-Okelobondo and Bangombe uranium deposits, in Gabon, Africa host Earth's only known natural nuclear fission reactors. These 2 billion year old reactors represent a unique opportunity to study used nuclear fuel over geologic periods of time. The reactors in these deposits have been studied as a means by which to constrain the source term of fission product concentrations produced during reactor operation. The source term depends on the neutronic parameters, which include reactor operation duration, neutron flux and the neutron energy spectrum. Reactor operation has been modeled using a point-source computer simulation (Oak Ridge Isotope Generation and Depletion, ORIGEN, code) for a light water reactor. Model results have been constrained using secondary ionization mass spectroscopy (SIMS) isotopic measurements of the fission products Nd and Te, as well as U in uraninite from samples collected in the Okelobondo reactor zone. Based upon the constraints on the operating conditions, the pre-reactor concentrations of Nd (150 ppm +/- 75 ppm) and Te (operation were calculated as a function of burnup. These results provide a source term against which the present elemental and decay abundances at the fission reactor can be compared. Furthermore, they provide new insights into the extent to which a "fossil" nuclear reactor can be characterized on the basis of its isotopic signatures. In addition, results from the study of two other natural systems related to the radionuclide and fission product transport are included. A detailed mineralogical characterization of the uranyl mineralogy at the Bangombe uranium deposit in Gabon, Africa was completed to improve geochemical models of the solubility-limiting phase. A study of the competing effects of radiation damage and annealing in a U-bearing crystal of zircon shows that low temperature annealing in actinide-bearing phases is significant in the annealing of radiation damage.

  17. Identification of neutron-rich isotope 197Os

    International Nuclear Information System (INIS)

    A new neutron-rich isotope 197Os was produced in the 198Pt(n, 2p) reaction by irradiating natural Pt targets with 14 MeV neutrons. The γ(X) singles spectrum and coincidence spectrum measurements were performed using two HPGe γ-ray detectors. Ten unknown γ-rays at 41.2, 50.7, 196.8, 199.6, 223.9, 233.1, 250.2, 342.1, 403.6, and 460.4 keV attributed to the decay of 197Os were observed in the experiments. The half-life of 197Os was found to be (2.8 ± 0.6) min. A partial decay scheme of 197Os was proposed on the basis of decay and coincidence relations. The half-life was compared with the values expected by different theoretical models. (authors)

  18. Progress in Development of Dense Plasma Focus Pinch for AmBe Radiological Source Replacement

    Science.gov (United States)

    Falabella, Steve; Povilus, Alex; Schmidt, Andrea; Ellsworth, Jennifer; Link, Anthony; Sears, Jason; Higginson, Drew; Jiang, Sheng

    2015-11-01

    A dense plasma focus (DPF) is a compact plasma gun accelerator that can produce intense, high energy ion beams (multiple MeV). These ion beams could be used to replace radiological sources for a variety of applications. Using a 2kJ DPF with a helium gas fill, alpha particles are accelerated into a beryllium target in order to generate a neutron spectrum similar to an AmBe source. We report on initial observations of neutron yields for this system and efforts to optimize and improve repeatability of pinch performance. In particular, incorporating results from newly-developed kinetic LSP simulations, we demonstrated higher neutron yields by adjusting the geometry of the anode electrode. In addition, we present preliminary measurements for energy distributions of ions accelerated by the pinch. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development.

  19. Shell evolution in neutron-rich carbon isotopes: Unexpected enhanced role of neutron–neutron correlation

    International Nuclear Information System (INIS)

    Full shell-model diagonalization has been performed to study the structure of neutron-rich nuclei around 20C. We investigate in detail the roles played by the different monopole components of the effective interaction in the evolution of the N=14 shell in C, N and O isotopes. It is found that the relevant neutron–neutron monopole terms, Vd5/2d5/2nn and Vs1/2s1/2nn, contribute significantly to the reduction of the N=14 shell gap in C and N isotopes in comparison with that in O isotopes. The origin of this unexpectedly large effect, which is comparable with (sometimes even larger than) that caused by the proton–neutron interaction, is related to the enhanced configuration mixing in those nuclei due to many-body correlations. Such a scheme is also supported by the large B(E2) value in the nucleus 20C which has been measured recently.

  20. A cyclic neutron activation system using an isotopic neutron source for the measurement of short-lived isotopes

    International Nuclear Information System (INIS)

    The design and construction of an activation analysis system using an isotopic neutron source which allows the measurement of prompt and delay gamma-rays, in conventional activation and cyclic activation modes, is briefly described with emphasis laid on its flexibility, transportability and low cost. Photon spectra obtained from the irradiation of large samples under prompt, delay and cyclic conditions using both NaI(Tl) and Ge(Li) detectors are presented and described with respect to 'in-vivo' neutron activation analysis and the measurement of N, O, Na, P, Cl and Cd. It is pointed out that, despite the attractive possibility of measuring Se in liver, 'in-vivo', by cyclic activation analysis, the system may potentially prove a very useful tool for industrial and other non-medical applications. (author)

  1. Evaluation of neutron nuclear data on iodine isotopes

    International Nuclear Information System (INIS)

    Neutron nuclear data on six isotopes of iodine have been evaluated for the next version of Japanese Evaluated Nuclear Data Library (JENDL) general-purpose file in the energy region from 10-5 eV to 20 MeV. Unresolved resonance parameters were obtained by fitting to the total and capture cross sections calculated from nuclear models, while resolved resonance parameters remain unchanged from JENDL-4.0. A statistical model code was applied to evaluate the cross sections above the resolved resonance region. Coupled-channel optical model parameters were employed for the interaction between neutrons and nuclei. Compound, pre-equilibrium and direct-reaction processes were considered for cross-section calculation in high-energy region. Giant-dipole resonance parameters for γ-ray transition from iodine isotopes were determined so as to reproduce measured γ-ray spectrum for 127I. The present results reproduce experimental data very well. The evaluated data are compiled into ENDF-formatted data files. (author)

  2. Ground-state properties of neutron-rich Mg isotopes

    CERN Document Server

    Watanabe, Shin; Shimada, Mitsuhiro; Tagami, Shingo; Kimura, Masaaki; Takechi, Maya; Fukuda, Mitsunori; Nishimura, Daiki; Suzuki, Takeshi; Matsumoto, Takuma; Shimizu, Yoshifumi R; Yahiro, Masanobu

    2014-01-01

    We analyze recently-measured total reaction cross sections for 24-38Mg isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model and antisymmetrized molecular dynamics(AMD). The folding model well reproduces the measured reaction cross sections, when the projectile densities are evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation. Matter radii of 24-38Mg are then deduced from the measured reaction cross sections by ?ne-tuning the parameters of the def-WS model. The deduced matter radii are largely enhanced by nuclear deformation. Fully-microscopic AMD calculations with no free parameter well reproduce the deduced matter radii for 24-36Mg, but still considerably underestimate them for 37,38Mg. The large matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD also reproduces other existing measured ground-state properties (spin-parity, total binding energy, and one-neutron separation energy) of Mg isotopes. Neutron-number (N) dependence of defor...

  3. High Flux Isotope Reactor cold neutron source reference design concept

    International Nuclear Information System (INIS)

    In February 1995, Oak Ridge National Laboratory's (ORNL's) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH2) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH2 cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept

  4. High Flux Isotope Reactor cold neutron source reference design concept

    Energy Technology Data Exchange (ETDEWEB)

    Selby, D.L.; Lucas, A.T.; Hyman, C.R. [and others

    1998-05-01

    In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

  5. Shape coexistence in the neutron-deficient Pt isotopes in a configuration mixing IBM

    International Nuclear Information System (INIS)

    The recently proposed matrix-coherent state approach for configuration mixing IBM is used to describe the evolving geometry of the neutron deficient Pt isotopes. It is found that the Potential Energy Surface (PES) of the Platinum isotopes evolves, when the number of neutrons decreases, from spherical to oblate and then to prolate shapes, in agreement with experimental measurements. Oblate-Prolate shape coexistence is observed in 194,192Pt isotopes

  6. Gamow-Teller response in deformed even and odd neutron-rich Zr and Mo isotopes

    OpenAIRE

    Sarriguren, Pedro; Algora, Alejandro; Pereira, J

    2014-01-01

    β-decay properties of neutron-rich Zr and Mo isotopes are investigated within a microscopic theoretical approach based on the proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual separable particle-hole and particle-particle forces are also included in the formalism. The structural evolution in these isotopic chains including both even and odd isotope...

  7. Observation of Large Enhancement of Charge Exchange Cross Sections with Neutron-Rich Carbon Isotopes

    CERN Document Server

    Tanihata, I; Kanungo, R; Ameil, F; Atkinson, J; Ayyad, Y; Cortina-Gil, D; Dillmann, I; Estradé, A; Evdokimov, A; Farinon, F; Geissel, H; Guastalla, G; Janik, R; Knoebel, R; Kurcewicz, J; Litvinov, Yu A; Marta, M; Mostazo, M; Mukha, I; Nociforo, C; Ong, H J; Pietri, S; Prochazka, A; Scheidenberger, C; Sitar, B; Strmen, P; Takechi, M; Tanaka, J; Toki, H; Vargas, J; Winfield, J S; Weick, H

    2015-01-01

    Production cross sections of nitrogen isotopes from high-energy carbon isotopes on hydrogen and carbon targets have been measured for the first time for a wide range of isotopes. The fragment separator FRS at GSI was used to deliver C isotope beams. The cross sections of the production of N isotopes were determined by charge measurements of forward going fragments. The cross sections show a rapid increase with the number of neutrons in the projectile. Since the production of nitrogen is mostly due to charge exchange reactions below the proton separation energies, the present data suggests a concentration of Gamow-Teller and Fermi transition strength at low excitation energies for neutron-rich isotopes. It was also observed that the cross sections were enhanced much more strongly for neutron rich isotopes in the C-target data.

  8. Shape coexistence in the neutron-deficient Pt isotopes in the configuration-mixed IBM

    International Nuclear Information System (INIS)

    The matrix-coherent state approach in the IBM with configuration mixing is used to describe the geometry of neutron-deficient Pt isotopes. Employing a parameter set for all isotopes determined previously, it is found that the lowest minimum goes from spherical to oblate and finally acquires a prolate shape when approaching the mid-shell Pt isotopes

  9. Production of neutron-rich Ca isotopes in transfer-type reactions

    International Nuclear Information System (INIS)

    Possibilities of production of neutron-rich isotopes 56,58,60Ca in transfer-type reactions are analyzed. The optimal conditions for their production are suggested. The neutron separation energies in nuclei near the neutron drip line can be estimated by measuring the excitation functions

  10. Laser isotope and isomer separation of neutron-rich Ag-isotopes

    International Nuclear Information System (INIS)

    In a recent experiment at CERN/ISOLDE, we have used laser isotope separation to isolate heavy Ag nuclides including the N=82 r-process 'waiting-point' isotope 129Ag. A half-life of 46(+5/-9) ms for the πg9/2 ground-state decay of 129Ag could be determined using beta-delayed neutron counting. In the case of 126Ag and 128Ag decays, γ-spectroscopic techniques with time resolving multi-channel-analysers were used to identify the 2+ and 4+ levels in 126Cd and 128Cd, respectively. The hyperfine splitting of the atomic transition in Ag which is used for laser ionization has made possible an isomer selection through which the β- and γ-decay of the high-spin isomer of 122Ag were observed while suppressing the ionization of the low-spin isomer

  11. Neutron Interactions as Seen by A Segmented Germanium Detector

    OpenAIRE

    Abt, I.; A. Caldwell; Kroeninger, K.; Liu, J.; Liu, X.; Majorovits, B.

    2007-01-01

    The GERmanium Detector Array, GERDA, is designed for the search for ``neutrinoless double beta decay'' (0-nu-2-beta) with germanium detectors enriched in Ge76. An 18-fold segmented prototype detector for GERDA Phase II was exposed to an AmBe neutron source to improve the understanding of neutron induced backgrounds. Neutron interactions with the germanium isotopes themselves and in the surrounding materials were studied. Segment information is used to identify neutron induced peaks in the rec...

  12. New source moderator geometry to improve performance of 252Cf and 241Am Be source-based PGNAA setups

    Science.gov (United States)

    Naqvi, A. A.; Abdelmonem, M. S.; Al-Misned, Ghada; Al-Ghamdi, Hanan

    2006-06-01

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups.

  13. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  14. Investigation of the structure of neutron-deficient Cd isotopes

    Science.gov (United States)

    Simon, Anna; Humby, P.; Beausang, C. W.; Burke, J. T.; Casperson, R. J.; McCleskey, M.; Saastamoinen, A.; Allmond, J. M.; Chyzh, R.; Dag, M.; Koglin, J.; Ota, S.; Ross, T. J.

    2014-03-01

    The STARLITER setup at Texas A&M University consists of an array of six Compton suppressed HPGe clover γ-ray detectors coupled with a segmented Si ΔE-E charged particle telescope. The combination allows for coincident γ ray and particle spectroscopy and provides a powerful tool for precise determination of the nuclear level structure. A recent experiment conducted using STARLITER aimed at the investigation of structures of neutron-deficient Cd isotopes (A = 104, 105, 106) using an enriched 106Cd target and 35 MeV proton beam supplied by the K-150 Cyclotron at TAMU. Low mass cadmium isotopes are a great environment for analysis of the evolution from vibrational to rotational sequences in A ~100-110 region and provide insight into the structure phenomena around Z = 50 shell closure. Here, the first results of the experiment will be presented. This work was partly supported by the US Department of Energy Grants No. DE-FG52-06NA26206 and No. DE-FG02-05ER41379.

  15. A systematical study of neutron-rich Zr isotopes by the projected shell model

    International Nuclear Information System (INIS)

    To understand the structure of neutron-rich nuclei and to validate the existing theoretical model for the exotic mass region, we study systematically strongly-deformed, neutron-rich even-even and odd-mass Zr isotopes with neutron number 61-66. With the projected shell model, the known experimental data are reproduced and some low-lying side-bands are predicted. The influence of the high-jh11/2 neutron orbital and the g9/2 proton orbital on the structure properties is investigated. For even-even isotopes, the structure of multi-quasiparticle bands is analyzed and some properties of the yrast line are described in detail. For odd-neutron isotopes, the discussion is focused on the excited single-particle configurations. Our predictions may help future experiments with identification of band structures in the very neutron-rich nuclei.

  16. Di-neutron correlation in soft octupole excitations of neutron-rich Ni isotopes beyond N=50

    OpenAIRE

    Serizawa, Yasuyoshi; Matsuo, Masayuki

    2008-01-01

    We investigate low-lying octupole response of neutron-rich Ni isotopes beyond the N=50 shell closure using the Skyrme-Hartree-Fock-Bogoliubov mean-fields and the continuum quasi-particle random phase approximation. Performing detailed numerical analyses employing the Skyrme parameter set SLy4 and a density-dependent delta interaction of the mixed type, we show that a neutron mode emerges above the neutron separation energy as a consequence of the weak binding of neutrons and it exhibits stron...

  17. Structure of the neutron-rich lithium isotopes in heavy-ion reactions

    International Nuclear Information System (INIS)

    The structure properties, for factors, angular distributions and interaction cross sections of Li neutron-rich isotopes have been analyzed in the unified way. A good qualitative agreement with the experiment data was obtained. 20 refs.; 11 figs.; 1 tab

  18. Evaluation and Compilation of Neutron Activation Cross Sections for Medical Isotope Production

    International Nuclear Information System (INIS)

    Calculational assessment and experimental verification of certain neutron cross sections that are related to widely needed new medical isotopes. Experiments were performed at the Oregon State University TRIGA Reactor and the High Flux Irradiation Reactor at Oak Ridge National Laboratory

  19. Production of actinide isotopes in simulated PWR fuel and their influence on inherent neutron emission

    International Nuclear Information System (INIS)

    This report describes calculations that examine the sensitivity of actinide isotopes to various reactor parameters. The impact of actinide isotope build-up, depletion, and decay on the neutron source rate in a spent-fuel assembly is determined, and correlations between neutron source rates and spent-fuel characteristics such as exposure, fissile content, and plutonium content are established. The application of calculations for evaluating experimental results is discussed

  20. ISOLDE beams of neutron-rich zinc isotopes yields, release, decay spectroscopy

    CERN Document Server

    Köster, U; Clausen, C; Delahaye, P; Fedosseev, V; Fraile-Prieto, L M; Gernhäuser, R; Gilles, T J; Ionan, A; Kröll, T; Mach, H; Marsh, B; Seliverstov, D M; Sieber, T; Siesling, E; Tengborn, E; Wenander, F; Van de Walle, J

    2005-01-01

    Intense radioactive ion beams of the neutron-rich zinc isotopes 69-81Zn have been produced at the isotope on-line facility ISOLDE at CERN. The combined use of spallations-neutron induced fission of 238UC_x targets and resonant laser ionization provided sufficient suppression of disturbing isobars (mainly gallium and rubidium) to perform decay spectroscopy up to 81Zn.

  1. ISOLDE beams of neutron-rich zinc isotopes: yields, release, decay spectroscopy

    International Nuclear Information System (INIS)

    Intense radioactive ion beams of the neutron-rich zinc isotopes 69-81Zn have been produced at the isotope separation on-line facility ISOLDE at CERN. The combined use of spallation-neutron induced fission of 238UCx targets and resonant laser ionization provided sufficient suppression of disturbing isobars (mainly gallium and rubidium) to perform decay spectroscopy up to 81Zn. (authors)

  2. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    International Nuclear Information System (INIS)

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-πBaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  3. Study of neutron-rich $^{51−53}$ Ca isotopes via $\\beta$-decay

    CERN Multimedia

    The high Q-$\\beta$ values in certain neutron-rich regions of the chart of nuclides opens up the possibility to study states in the daughter nuclei which lie at high excitation energy, above the neutron separation threshold. We propose to perform spectroscopy of the $\\beta$-delayed neutron emission of the $^{51-53}$K isotopes to study the population of single-particle or particle-hole states both below and above the neutron separation threshold. The VANDLE neutron detector will be used in combination with the IDS tape station setup and Ge detectors.

  4. Impact of statistical uncertainty of the neutron spectrum in the isotopic evolution of fuel

    International Nuclear Information System (INIS)

    The results obtained and presented in this study for different calculation conditions (number of stories, number of steps burning, etc.) and their simultaneous impact on neutron spectrum and isotopic composition and a methodology is proposed to determine the minimum parameters for calculation given uncertainty in the results of isotopic composition with high burnup, both UO2 and MOX fuel.

  5. Production of neutron-rich isotopes in transfer-type reactions

    International Nuclear Information System (INIS)

    The production yields of new neutron-rich 84,86Zn and 90,92Ge isotopes beyond N=50 and isotopes of nuclei with charge numbers Z=64-80 are estimated for future experiments in the multinucleon transfer reactions at energies close to the Coulomb barrier. (author)

  6. Discovery of 40Mg and 42Al suggests neutron drip-line slant towards heavier isotopes.

    Science.gov (United States)

    Baumann, T; Amthor, A M; Bazin, D; Brown, B A; Folden, C M; Gade, A; Ginter, T N; Hausmann, M; Matos, M; Morrissey, D J; Portillo, M; Schiller, A; Sherrill, B M; Stolz, A; Tarasov, O B; Thoennessen, M

    2007-10-25

    A fundamental question in nuclear physics is what combinations of neutrons and protons can make up a nucleus. Many hundreds of exotic neutron-rich isotopes have never been observed; the limit of how many neutrons a given number of protons can bind is unknown for all but the lightest elements, owing to the delicate interplay between single particle and collective quantum effects in the nucleus. This limit, known as the neutron drip line, provides a benchmark for models of the atomic nucleus. Here we report a significant advance in the determination of this limit: the discovery of two new neutron-rich isotopes--40Mg and 42Al--that are predicted to be drip-line nuclei. In the past, several attempts to observe 40Mg were unsuccessful; moreover, the observation of 42Al provides an experimental indication that the neutron drip line may be located further towards heavier isotopes in this mass region than is currently believed. In stable nuclei, attractive pairing forces enhance the stability of isotopes with even numbers of protons and neutrons. In contrast, the present work shows that nuclei at the drip line gain stability from an unpaired proton, which narrows the shell gaps and provides the opportunity to bind many more neutrons. PMID:17960237

  7. Mass measurements of neutron-rich Rb and Sr isotopes

    Science.gov (United States)

    Klawitter, R.; Bader, A.; Brodeur, M.; Chowdhury, U.; Chaudhuri, A.; Fallis, J.; Gallant, A. T.; Grossheim, A.; Kwiatkowski, A. A.; Lascar, D.; Leach, K. G.; Lennarz, A.; Macdonald, T. D.; Pearkes, J.; Seeraji, S.; Simon, M. C.; Simon, V. V.; Schultz, B. E.; Dilling, J.

    2016-04-01

    We report on the mass measurements of several neutron-rich Rb and Sr isotopes in the A ≈100 region with the TITAN Penning-trap mass spectrometer. By using highly charged ions in the charge state q =10 + , the masses of Rb,9998 and Sr-10098 have been determined with a precision of 6-12 keV, making their uncertainty negligible for r -process nucleosynthesis network calculations. The mass of 101Sr has been determined directly for the first time with a precision eight times higher than the previous indirect measurement and a deviation of 3 σ when compared to the Atomic Mass Evaluation. We also confirm the mass of 100Rb from a previous measurement. Furthermore, our data indicate the existence of a low-lying isomer with 80 keV excitation energy in 98Rb. We show that our updated mass values lead to minor changes in the r process by calculating fractional abundances in the A ≈100 region of the nuclear chart.

  8. Mass measurements of neutron-rich Rb and Sr isotopes

    CERN Document Server

    Klawitter, R; Brodeur, M; Chowdhury, U; Chausdhuri, A; Fallis, J; Gallant, A T; Grossheim, A; Kwiatkowski, A A; Lascar, D; Leach, K G; Lennarz, A; Macdonald, T D; Pearkes, J; Seeraji, S; Simon, M C; Simon, V V; Schultz, B E; Dilling, J

    2015-01-01

    We report on the mass measurements of several neutron-rich $\\mathrm{Rb}$ and $\\mathrm{Sr}$ isotopes in the $A \\approx 100$ region with the TITAN Penning-trap mass spectrometer. Using highly charged ions in the charge state $q=10+$, the masses of $^{98,99}\\mathrm{Rb}$ and $^{98-100}\\mathrm{Sr}$ have been determined with a precision of $6 - 12\\ \\mathrm{keV}$, making their uncertainty negligible for r-process nucleosynthesis network calculations. The mass of $^{101}\\mathrm{Sr}$ has been determined directly for the first time with a precision eight times higher than the previous indirect measurement and a deviation of $3\\sigma$ when compared to the Atomic Mass Evaluation. We also confirm the mass of $^{100}\\mathrm{Rb}$ from a previous measurement. Furthermore, our data indicates the existance of a low-lying isomer with $80\\ \\mathrm{keV}$ excitation energy in $^{98}\\mathrm{Rb}$. We show that our updated mass values lead to minor changes in the r-process by calculating fractional abundances in the $A\\approx 100$ re...

  9. Study of the stability of the gallium isotopes beyond the N = 50 neutron shell closure

    CERN Multimedia

    We propose to study the stability of the nuclear structure beyond N = 50 and Z = 28 with beams of neutron-rich gallium isotopes at the CRIS experiment at ISOLDE. The study of their hyperne structure and isotope shift will provide spins, magnetic dipole moments, electric quadrupole moments and changes in the mean-square charge radii. The $\\beta$-decay of $^{80}$Ga will be unambiguously measured using the technique of Laser Assisted Nuclear Decay Spectroscopy (LANDS). The half-lives of the very neutron-rich isotopes with N > 54 will be measured for their impact on the astrophysical ${r}$-process.

  10. Optical polarization of neutron-rich sodium isotopes and $\\beta$-NMR measurements of quadrupole moments

    CERN Document Server

    Keim, M; Klein, A; Neugart, R; Neuroth, M; Wilbert, S; Lievens, P; Vermeeren, L

    1995-01-01

    The nuclear quadrupole moments of neutron-rich sodium isotopes are being investigated with the help of in-beam polarization by optical pumping in combination with $\\beta$-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO$_{3}$ for the isotopes $^{26}$Na, $^{27}$Na and $^{28}$Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments, $\\beta$-decay asymmetries for the sequence of isotopes up to the $N$=20 neutron shell closure, $^{26-31}$Na, have been measured.

  11. Measurement of uranium and plutonium in solid waste by passive photon or neutron counting and isotopic neutron source interrogation

    International Nuclear Information System (INIS)

    A summary of the status and applicability of nondestructive assay (NDA) techniques for the measurement of uranium and plutonium in 55-gal barrels of solid waste is reported. The NDA techniques reviewed include passive gamma-ray and x-ray counting with scintillator, solid state, and proportional gas photon detectors, passive neutron counting, and active neutron interrogation with neutron and gamma-ray counting. The active neutron interrogation methods are limited to those employing isotopic neutron sources. Three generic neutron sources (alpha-n, photoneutron, and 252Cf) are considered. The neutron detectors reviewed for both prompt and delayed fission neutron detection with the above sources include thermal (3He, 10BF3) and recoil (4He, CH4) proportional gas detectors and liquid and plastic scintillator detectors. The instrument found to be best suited for low-level measurements (252Cf Shuffler. The measurement technique consists of passive neutron counting followed by cyclic activation using a 252Cf source and delayed neutron counting with the source withdrawn. It is recommended that a waste assay station composed of a 252Cf Shuffler, a gamma-ray scanner, and a screening station be tested and evaluated at a nuclear waste site. 34 figures, 15 tables

  12. Study of Neutron-Deficient $^{202-205}$Fr Isotopes with Collinear Resonance Ionization Spectroscopy

    CERN Document Server

    De Schepper, Stijn; Cocolios, Thomas; Budincevic, Ivan

    The scope of this master’s thesis is the study of neutron-deficient $^{202−205}$Fr isotopes. These isotopes are inside the neutron-deficient lead region, a region that has shown evidence of shape coexistence. For this thesis, this discussion is limited to the phenomenon where a low lying excited state has a different shape than the ground state. Shape coexistence is caused by intruder states. These are single-particle Shell Model states that are perturbed in energy due to the interaction with a deformed core. In the neutron-deficient lead region the main proton intruder orbit is the 3s$_{1/2}$orbit. When going towards more neutron-deficient isotopes, deformation increases. The $\\pi3s_{1/2}$orbit will rise in energy and will eventually become the ground state in odd- A bismuth (Z=83) isotopes. It is also observed in odd-A astatine (Z=85) isotopes, already in less neutron-deficient nuclei. The same phenomenon is expected to be present francium (Z=87) isotopes already at $^{199}$Fr. Although it is currently ...

  13. Gamow-Teller response in deformed even and odd neutron-rich Zr and Mo isotopes

    CERN Document Server

    Sarriguren, P; Pereira, J

    2014-01-01

    Beta-decay properties of neutron-rich Zr and Mo isotopes are investigated within a microscopic theoretical approach based on the proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual separable particle-hole and particle-particle forces are also included in the formalism. The structural evolution in these isotopic chains including both even and odd isotopes is analyzed in terms of the equilibrium deformed shapes. Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron-emission probabilities are studied, stressing their relevance to describe the path of the nucleosynthesis rapid neutron capture process.

  14. Production and investigation of neutron-rich Osmium isotopes with and around N=126 using gas flow transport method

    International Nuclear Information System (INIS)

    Neutron-rich isotopes of heavy nuclei are until now poorly studied. In this work we investigate neutron-rich osmium isotopes produced in multi-nucleon transfer reactions. The reaction 136Xe+208Pb at energy near Coulomb barrier is used for production of osmium isotopes. The CORSAR-V setup is used to record the characteristics of osmium isotopes. The separation of the reaction products is based on their respective volatility. Experimental results are presented and discussed.

  15. Calculation of neutron cross sections on isotopes of yttrium and zirconium

    International Nuclear Information System (INIS)

    Multistep Hauser-Feshbach calculations with preequilibrium corrections were made for neutron-induced reactions on yttrium and zirconium isotopes between 0.001 and 20 MeV. Recently new neutron cross-section data have been measured for unstable isotopes of these elements. These data, along with results from charged-particle simulation of neutron reactions, provide unique opportunities under which to test nuclear-model techniques and parameters in this mass region. A complete and consistent analysis of varied neutron reaction types using input parameters determined independently from additional neutron and charged-particle data. The overall agreement between calculations and a wide variety of experimental results available for these nuclei leads to increased confidence in calculated cross sections made where data are incomplete or lacking. 75 references

  16. Disentangling the Effects of Thickness of the Neutron Skin and Symmetry Potential in Nucleon Induced Reactions on Sn Isotopes

    Institute of Scientific and Technical Information of China (English)

    OU Li; LI Zhu-Xia; WU Xi-Zhen; SUN Wei-Li

    2009-01-01

    The effects of density dependence of symmetry energy and the thickness of the neutron skin in proton (neutron)induced reactions on Sn isotopes are investigated by means of the improved molecular dynamics model. The investigation shows that the target size dependence of the reaction cross sections for proton induced reactions on Sn isotopes is sensitive to the density dependence of the symmetry energy and less sensitive to the thickness of the neutron skin of the target nuclei, but that, for neutron induced reactions on Sn isotopes, it is less sensitive to the density dependence of the symmetry energy and sensitive to the thickness of the neutron skin of the target nucleus.

  17. Neutron-Proton Asymmetry Dependence of Spectroscopic Factors in Ar Isotopes

    International Nuclear Information System (INIS)

    Spectroscopic factors have been extracted for proton-rich 34Ar and neutron-rich 46Ar using the (p, d) neutron transfer reaction. The experimental results show little reduction of the ground state neutron spectroscopic factor of the proton-rich nucleus 34Ar compared to that of 46Ar. The results suggest that correlations, which generally reduce such spectroscopic factors, do not depend strongly on the neutron-proton asymmetry of the nucleus in this isotopic region as was reported in knockout reactions. The present results are consistent with results from systematic studies of transfer reactions but inconsistent with the trends observed in knockout reaction measurements.

  18. Neutron-rich polonium isotopes studied with in-source laser spectroscopy

    CERN Document Server

    Dexters, Wim; Cocolios, T E

    This work studies the unknown region of neutron rich polonium isotopes. The polonium isotopes, with Z=84, lie above the magic lead nuclei (Z=82). The motivation for this research can mainly be found in these lead nuclei. When looking at the changes in the mean square charge radii beyond the N=126 shell gap, a kink is observed. This kink is also found in the radon (Z=86) and radium (Z=88) isotopes. The observed effect cannot be reproduced with our current models. The polonium isotopes yield more information on the kink and they are also able to link the known charge radii in lead isotopes to those in radon and radium. Additionally, the nuclear moments of the odd-neutron isotope $^{211}$Po are investigated. This nucleus has two protons and one neutron more than the doubly magic nucleus $^{208}$Pb. Nuclear moments of isotopes close to this doubly magic nucleus are good tests for the theoretic models. Besides pushing the models to their limits, the nuclear moments of $^{211}$Po also yield new information on the f...

  19. Monte Carlo optimization of sample dimensions of an {sup 241}Am-Be source-based PGNAA setup for water rejects analysis

    Energy Technology Data Exchange (ETDEWEB)

    Idiri, Z. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria)]. E-mail: zmidiri@yahoo.fr; Mazrou, H. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria); Beddek, S. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria); Amokrane, A. [Faculte de Physique, Universite des Sciences et de la Technologie Houari-Boumediene (USTHB), Alger (Algeria); Azbouche, A. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria)

    2007-07-21

    The present paper describes the optimization of sample dimensions of a {sup 241}Am-Be neutron source-based Prompt gamma neutron activation analysis (PGNAA) setup devoted for in situ environmental water rejects analysis. The optimal dimensions have been achieved following extensive Monte Carlo neutron flux calculations using MCNP5 computer code. A validation process has been performed for the proposed preliminary setup with measurements of thermal neutron flux by activation technique of indium foils, bare and with cadmium covered sheet. Sensitive calculations were subsequently performed to simulate real conditions of in situ analysis by determining thermal neutron flux perturbations in samples according to chlorine and organic matter concentrations changes. The desired optimal sample dimensions were finally achieved once established constraints regarding neutron damage to semi-conductor gamma detector, pulse pile-up, dead time and radiation hazards were fully met.

  20. Ground-state properties and symmetry energy of neutron-rich and neutron-deficient Mg isotopes

    CERN Document Server

    Gaidarov, M K; Antonov, A N; de Guerra, E Moya

    2015-01-01

    A comprehensive study of various ground-state properties of neutron-rich and neutron-deficient Mg isotopes with $A$=20-36 is performed in the framework of the self-consistent deformed Skyrme-Hartree-Fock plus BCS method. The correlation between the skin thickness and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for this isotopic chain following the theoretical approach based on the coherent density fluctuation model and using the Brueckner energy-density functional. The results of the calculations show that the behavior of the nuclear charge radii and the nuclear symmetry energy in the Mg isotopic chain is closely related to the nuclear deformation. We also study, within our theoretical scheme, the emergence of an "island of inversion" at neutron-rich $^{32}$Mg nucleus, that was recently proposed from the analyses of spectroscopic measurements of $^{32}$Mg low-lying energy spectrum and the charge rms radii of all magnesium isotopes in the $sd$ shell.

  1. Isotope identification capabilities using time resolved prompt gamma emission from epithermal neutrons

    International Nuclear Information System (INIS)

    We present a concept of integrated measurements for isotope identification which takes advantage of the time structure of spallation neutron sources for time resolved γ spectroscopy. Time resolved Prompt Gamma Activation Analysis (T-PGAA) consists in the measurement of gamma energy spectrum induced by the radioactive capture as a function of incident neutron Time Of Flight (TOF), directly related with the energy of incident neutrons. The potential of the proposed concept was explored on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (U.K.). Through this new technique we show an increase in the sensitivity to specific elements of archaeometric relevance, through incident neutron energy selection in prompt γ spectra for multicomponent samples. Results on a standard bronze sample are presented

  2. Signatures of structural changes in neutron-rich Sr, Zr and Mo isotopes

    International Nuclear Information System (INIS)

    The evolution of the ground-state nuclear shapes in neutron-rich Sr, Zr, and Mo isotopes, including both even-even and odd-A nuclei, is discussed within the mean-field approximation based on the Gogny-D1S Gogny Energy Density Functional. Calculations for neutron separation energies and charge radii are presented and compared with available data. A correlation between a shape transition and a discontinuity in those observables is found within our microscopic framework. It is shown that, while in Sr and Zr isotopes the steep behavior observed in the isotopic dependence of the charge radii is a consequence of a sharp prolate-oblate transition, the smooth behavior found in Mo isotopes has its origin in an emergent region of triaxiality.

  3. Study of neutron-rich Mo isotopes by the projected shell model approach

    Indian Academy of Sciences (India)

    Gopal Krishan; Rawan Kumar; Rani Devi; S K Khosa

    2014-09-01

    The projected shell model (PSM) calculations have been performed for the neutron-rich even–even 102−110Mo and odd–even 103−109Mo isotopes. The present calculation reproduces the available experimental data on the yrast bands. In case of even–even nuclei, the structure of yrast bands is analysed and electromagnetic quantities are compared with the available experimental data. The -factors have been predicted for high spin states. For the odd-neutron nuclei, the structures of yrast positive- and negative-parity bands are analysed and found to be in reasonable agreement with the experiments for 103−107Mo. The disagreement of the calculated and observed plots for energy staggering quantity clearly establishes the occurrence of sizable triaxiality in 103,105Mo and also predicts a decrease in the quantum of triaxiality with increasing neutron number and angular momentum for odd mass neutron-rich Mo isotopes.

  4. Neutron skin effect of some Mo isotopes in pre-equilibrium reactions

    Indian Academy of Sciences (India)

    M H Bölükdemir; E Tel; S Okuducu; N N Akti

    2011-03-01

    The neutron skin effect has been investigated for even isotopes of molybdenum at 25.6 MeV 94−100Mo(, ) reaction using the geometry-dependent hybrid model of pre-equilibrium nuclear reactions. Here the initial neutron/proton exciton numbers were calculated from the neutron/proton densities obtained from an effective nucleon–nucleon interaction of the Skyrme type. Initial exciton numbers from different radii of even Mo isotopes were used to obtain the corresponding neutron emission spectra. In this investigation the calculated results are compared with the experimental data as also with each other. The results using central densities in the geometry-dependent hybrid model are in better agreement with the experimental data.

  5. Search for long-lived isomeric states in neutron-deficient thorium isotopes

    CERN Document Server

    Lachner, J; Fästermann, T; Korschinek, G; Poutivtsev, M; Rugel, G; 10.1103/PhysRevC.78.064313

    2009-01-01

    The discovery of naturally occurring long-lived isomeric states (t_1/2 > 10^8 yr) in the neutron-deficient isotopes 211,213,217,218Th [A. Marinov et al., Phys. Rev. C 76, 021303(R) (2007)] was reexamined using accelerator mass spectrometry (AMS). Because AMS does not suffer from molecular isobaric background in the detection system, it is an extremely sensitive technique. Despite our up to two orders of magnitude higher sensitivity we cannot confirm the discoveries of neutron-deficient thorium isotopes and provide upper limits for their abundances.

  6. Study of asymmetric fission yield behavior from neutron-deficient Hg isotope

    Energy Technology Data Exchange (ETDEWEB)

    Perkasa, Y. S. [Department of Physics, Sunan Gunung Djati State Islamic University Bandung, Jl. A.H Nasution No. 105 Cibiru, Bandung (Indonesia); Waris, A., E-mail: awaris@fi.itb.ac.id; Kurniadi, R., E-mail: awaris@fi.itb.ac.id; Su' ud, Z., E-mail: awaris@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung 40132 (Indonesia)

    2014-09-30

    A study of asymmetric fission yield behavior from a neutron-deficient Hg isotope has been conducted. The fission yield calculation of the neutron-deficient Hg isotope using Brownian Metropolis shape had showed unusual result at decreasing energy. In this paper, this interesting feature will be validated by using nine degree of scission shapes parameterization from Brosa model that had been implemented in TALYS nuclear reaction code. This validation is intended to show agreement between both model and the experiment result. The expected result from these models considered to be different due to dynamical properties that implemented in both models.

  7. Isotopic mass dispersion discontinuity in various fission processes and its interpretation as a neutron shell effect

    International Nuclear Information System (INIS)

    The isotopic dispersions have been calculated for fission processes listed in the Introduction below by using recommended fission yield data. Those dispersions in which the neutron numbers of isotopes lying in the vicinity of the most probable mass fit a strong shell have been found to be pronouncedly discontinuous; the discontinuity is proved to occur exactly at the most probable mass. The influence of neutron shells on mass dispersion with special reference to discontinuity is discussed on the basis of shell correction versus deformation and neutron number reported by Wilkins, Steinberg, and Chasman. In discontinuous dispersions on the narrower branch lie the isotopes fitting the strong spherical and deformed neutron shells. Apart from recommended data, the relative isotopic fragment yields predicted by the Wilkins-Steinberg model for the complementary pairs z = 50-42, 51-41, 54-38, and 56-36, in thermal-neutron fission of 235U have also been used to calculate the corresponding dispersions. These have been found to be in good agreement with those calculated from recommended data, and discontinuities were observed, in general, wherever expected

  8. Calculations of neutron and proton radii of cesium isotopes. Final report, April 23--September 30, 1993

    International Nuclear Information System (INIS)

    This task involved the calculation of neutron and proton radii of cesium isotopes. The author has written a computer code that calculates radii according to two models: Myers 1983 and FRDM 1992. Results of calculations in both these models for both cesium and francium isotopes are attached as figures. He is currently interpreting these results in collaboration with D. Vieira and J.R. Nix, and they expect to use the computer code for further studies of nuclear radii

  9. Efigie: a computer program for calculating end-isotope accumulation by neutron irradiation and radioactive decay

    International Nuclear Information System (INIS)

    Efigie is a program written in Fortran V which can calculate the concentration of radionuclides produced by neutron irradiation of a target made of either a single isotope or several isotopes. The program includes optimization criteria that can be applied when the goal is the production of a single nuclide. The effect of a cooling time before chemical processing of the target is also accounted for.(author)

  10. Shape coexistence in the neutron deficient Pb isotopes and the configuration-constrained shell correction approach

    International Nuclear Information System (INIS)

    Calculations of shape-isomeric states in neutron deficient lead isotopes have been performed using the configuration-constrained shell correction method with a Woods-Saxon average potential and a monopole pairing interaction. This approach enables us to decompose the ground state potential energy surface in separate parts characterized uniquely by the number of occupied intruder orbitals. The calculations reproduce the positions of the excited 0+ intruder states. The isotope 196Pb is discussed in detail. (orig.)

  11. Beta-decay properties of Zr and Mo neutron-rich isotopes

    OpenAIRE

    Sarriguren, P.; Pereira, J

    2010-01-01

    Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron emission are investigated in neutron-rich Zr and Mo isotopes within a deformed quasiparticle random-phase approximation. The approach is based on a self-consistent Skyrme Hartree-Fock mean field with pairing correlations and residual separable particle-hole and particle-particle forces. Comparison with recent measurements of half-lives stresses the important role that nuclear deformation plays in the descript...

  12. Investigation of neutron-deficient isotopes in the barium-region

    International Nuclear Information System (INIS)

    Bombarding targets of 106Cd, 108Cd and 110Cd with 16O ions of 52.5-66.0 MeV neutron deficient barium, cesium and xenon isotopes were produced and have been studied using excitation functions and neutron-gamma, proton-gamma, alpha-gamma and gamma-gamma coincidence measurements. Partial level schemes for 123Ba and 121Ba were proposed. A number of gamma transitions was assigned to the different product nuclei. The measured particle emission probabilities from the compound nuclei are compared with different evaporation models. The models mostly underestimate neutron emission and often overestimate the emission of alpha particles. (orig.)

  13. First measurement of several $\\beta$-delayed neutron emitting isotopes beyond N=126

    CERN Document Server

    Caballero-Folch, R; Agramunt, J; Algora, A; Ameil, F; Arcones, A; Ayyad, Y; Benlliure, J; Borzov, I N; Bowry, M; Calvino, F; Cano-Ott, D; Cortés, G; Davinson, T; Dillmann, I; Estrade, A; Evdokimov, A; Faestermann, T; Farinon, F; Galaviz, D; García, A R; Geissel, H; Gelletly, W; Gernhäuser, R; Gómez-Hornillos, M B; Guerrero, C; Heil, M; Hinke, C; Knöbel, R; Kojouharov, I; Kurcewicz, J; Kurz, N; Litvinov, Y; Maier, L; Marganiec, J; Marketin, T; Marta, M; Martínez, T; Martínez-Pinedo, G; Montes, F; Mukha, I; Napoli, D R; Nociforo, C; Paradela, C; Pietri, S; Podolyák, Zs; Prochazka, A; Rice, S; Riego, A; Rubio, B; Schaffner, H; Scheidenberger, Ch; Smith, K; Sokol, E; Steiger, K; Sun, B; Taín, J L; Takechi, M; Testov, D; Weick, H; Wilson, E; Winfield, J S; Wood, R; Woods, P; Yeremin, A

    2015-01-01

    The $\\beta$-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with $\\beta$-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb and Bi in the mass region N$\\gtrsim$126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the $\\beta$-decay strength distribution. In doing so, it provides important constraints to global theoretical models currently used in $r$-process nucleosynthesis.

  14. Nuclear and dosimetric features of an isotopic neutron source

    Science.gov (United States)

    Vega-Carrillo, H. R.; Hernández-Dávila, V. M.; Rivera, T.; Sánchez, A.

    2014-02-01

    A multisphere neutron spectrometer was used to determine the features of a 239PuBe neutron source that is used to operate the ESFM-IPN Subcritical Reactor. To determine the source main features it was located a 100 cm from the spectrometer which was a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter polyethylene spheres. Count rates obtained with the spectrometer were unfolded using the NSDUAZ code and neutron spectrum, total fluence, and ambient dose equivalent were determined. A Monte Carlo calculation was carried out to estimate the spectrum and integral features being less than values obtained experimentally due to the presence of 241Pu in the Pu used to fabricate the source. Actual neutron yield and the mass fraction of 241Pu was estimated.

  15. Neutron activation analysis of stable isotopic tracers for studies of mineral bioavailability

    International Nuclear Information System (INIS)

    With increased recognition of the importance of trace minerals in nutrition it is necessary to investigate factors affecting their absorption. Enriched stable isotopic tracers with determination by neutron activation analysis or mass spectroscopy have been used to investigate the absorption of minerals by term and pre-term babies and to compare their absorption from infant formulae, without any radiological risk. (UK)

  16. Shape Coexistence in Neutron-Deficient At Isotopes in Relativistic Mean-Field Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The potential energy surfaces are calculated for neutron-deficient At isotopes from A = 190 to 207 in an axiaJJy deformed relativistic mean-field approach, using a quadratic constraint scheme for the first time. We find several minima in the potential energy surface for each nucleus, shape-coexistence, and quadratic deform are discussed.

  17. Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes

    CERN Document Server

    Marinov, A; Kashiv, Y; Halicz, L; Segal, I; Pape, A; Gentry, R V; Miller, H W; Kolb, D; Brandt, R

    2006-01-01

    Evidence for the existence of long-lived neutron-deficient isotopes has been found in a study of naturally-occurring Th using iductively coupled plasma-sector field mass spectrometry. They are interpreted as belonging to the recently discovered class of long-lived high spin super- and hyperdeformed isomers.

  18. Decay properties of neutron-deficient isotopes of elements from Z=101 to Z=108

    Energy Technology Data Exchange (ETDEWEB)

    Hessberger, F.P.; Sulignano, B.; Ackermann, D.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R. [GSI - Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Hofmann, S. [GSI - Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Kernphysik, Frankfurt (Germany); Streicher, B. [Comenius University Bratislava, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); GSI - Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Antalic, S.; Saro, S. [Comenius University Bratislava, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Kuusiniemi, P. [University of Oulu, CUPP, Oulu (Finland); Leino, M.; Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Popeko, A.G.; Yeremin, A.V. [JINR, Flerov Laboratory of Nuclear Reactions, Dubna (Russian Federation)

    2009-08-15

    In a series of experiments performed at the velocity filter SHIP, new or improved decay data of neutron-deficient isotopes of elements from mendelevium (Z=101) to hassium (Z=108) were obtained. In particular, evidence for {alpha}-decay or electron capture from isomeric states in {sup 265}Hs and {sup 258}Db was found. (orig.)

  19. Decay properties of neutron-deficient isotopes of elements from Z=101 to Z=108

    International Nuclear Information System (INIS)

    In a series of experiments performed at the velocity filter SHIP, new or improved decay data of neutron-deficient isotopes of elements from mendelevium (Z=101) to hassium (Z=108) were obtained. In particular, evidence for α-decay or electron capture from isomeric states in 265Hs and 258Db was found. (orig.)

  20. Neutron unbound resonances cataloged by isotope and invariant mass measurements for nuclei Z = 1-12

    Science.gov (United States)

    Havens, Elizabeth; Finck, Joseph; Gueye, Paul; Thoennessen, Michael; MoNA Collaboration

    2015-10-01

    Prior to 2014, no comprehensive study had been undertaken to compile experimental results from neutron unbound spectroscopy using invariant mass measurements, gamma resolutions and half-lives. Through the collaborative efforts of Central Michigan University, Hampton University and the NSCL, a project was initiated to catalog all unbound resonances in light nuclei (Z = 1-12). Unbound resonances were characterized by having a confirmed neutron decay branch and/or an energy level greater than the neutron binding energy listed for that isotope, according to either the NNDC's ENSDF or XUNDL and the referred journals therein. This was initially compiled in July 2014 and presented in October of that year. Recent discoveries and updates to NNDC have added ten isotopes and their resonances. Additionally, various corrections to previously compiled resonances have been made and equivalent evaluated and unevaluated invariant mass measurements have been consolidated into single entries. The neutron separation energy is noted for each isotope. The isotopes in which unbound resonances occur have been identified and, if known, each unbound resonance's gamma resolution, half-life, method of production and journal reference were also determined.

  1. Optimization of thermal neutron flux in an irradiator assembly with different isotopic sources

    International Nuclear Information System (INIS)

    Highlights: • The aim of this work, is to evaluate the thermal neutron distribution in an irradiator assembly. • Thermal neutron distribution were determined experimentally and calculated by MCNP. • The calculated and experimental results were in good agreement. - Abstract: This work aimed to determine the distribution of thermal neutron flux in an irradiator assembly to study the possibility of use this irradiator for Neutron Activation Analysis; NAA. To establish the facility specifications, the thermal neutron flux values of 252Cf and Pu-Be isotopic neutron sources along the horizontal irradiator axis were determined experimentally and calculated by Monte Carlo N-Particle; MCNP transport code. The irradiator assembly characterized by supplying a stable neutron flux for a long period, eliminating the need to use standard material i.e. comparative method, so that the process becomes efficient, compact, economical and more reliable. The measurements were carried out at different position inside the irradiator assembly using proportional 3He-detector and gold foil activation method. As well as, these measurements were performed without and with two types of neutron reflector such as water and steel to determine the thermal neutron distribution along the irradiation points. The experimental results were compared to the calculations performed with MCNP Code. The calculated and experimental results were in reasonable agreement for both 252Cf and Pu-Be sources. This indicated that the material and geometrical properties of the irradiator were modeled well

  2. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons

    International Nuclear Information System (INIS)

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons

  3. β-decay properties of neutron-deficient Pt, Hg, and Pb isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Sarriguren, P., E-mail: p.sarriguren@csic.es [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Boillos, J. M. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Universidad de Santiago de Compostela, 15706 Santiago de Compostela (Spain); Moreno, O. [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Moya de Guerra, E. [Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2015-10-15

    Neutron-deficient isotopes in the lead region are well established examples of the shape coexistence phenomenon in nuclei. In this work, bulk and decay properties, including deformation energy curves, charge mean square radii, Gamow-Teller (GT) strength distributions, and β-decay half-lives, are studied in neutron-deficient Pt, Hg, and Pb isotopes. The nuclear structure involved is described microscopically from deformed quasiparticle random-phase approximation calculations with residual interactions in both particle-hole and particle-particle channels, performed on top of a self-consistent deformed quasiparticle Skyrme Hartree-Fock basis. The sensitivity to deformation of the GT strength distributions in those isotopes is proposed as an additional complementary signature of the nuclear shape. The β-decay half-lives resulting from the GT strength distributions are compared to experiment to demonstrate the ability of the method.

  4. Isomers and oblate collectivity at high spin in neutron-rich Pt isotopes

    Directory of Open Access Journals (Sweden)

    Tandel S.K.

    2016-01-01

    Full Text Available Isomers and high-spin structures with rotation-aligned oblate configurations have been studied in several Pt isotopes. The 12+ states in the even Pt isotopes from 192–198Pt are found to be metastable, and have (i13/22 neutron character. The progression of E2 transition probabilities from the 12+ to 10+ states across the Pt isotopic chain implies reduction in collectivity, followed by an abrupt decrease at N=120 (198Pt. This behavior is quite distinct from the gradual decrease of B(E2 values near the respective ground states. A large contribution from aligned angular momentum, to the rotational sequences built on the 12+ states, is visible. This is due to the relatively small crossing frequencies for nucleons in low-Ω orbitals at oblate deformation in comparison to higher values for prolate shapes. As a result, oblate rotation is found to be increasingly favored for higher neutron numbers.

  5. Identification of a new heavy neutron-rich isotope 238Th

    International Nuclear Information System (INIS)

    A new heavy neutron-rich thorium isotope was produced via a multinucleon transfer reaction by irradiation of natural uranium targets with 60 MeV/u 18O ions. The Th activities was radiochemically separated from the uranium and mixture of reaction products by the rapid solvent extraction method. Measurements of the gamma-ray spectra were performed with HPGe detectors. The new neutron-rich isotope 238Th was identified for the first time based on the observation of the growth and decay of the gamma-ray with energy of 1060.5 keV from the decay of 238Pa. The half-life of 238Th has been determined to be 9.4±2.0 minutes. Further, a gamma-ray of 89.0 keV with the 8.9-minute half-life was found, which may be due to the decay of the new isotope 238Th. (author)

  6. Bulk - Samples gamma-rays activation analysis (PGNAA) with Isotopic Neutron Sources

    International Nuclear Information System (INIS)

    An overview is given on research towards the Prompt Gamma-ray Neutron Activation Analysis (PGNAA) of bulk-samples. Some aspects in bulk-sample PGNAA are discussed, where irradiation by isotopic neutron sources is used mostly for in-situ or on-line analysis. The research was carried out in a comparative and/or qualitative way or by using a prior knowledge about the sample material. Sometimes we need to use the assumption that the mass fractions of all determined elements add up to 1. The sensitivity curves are also used for some elements in such complex samples, just to estimate the exact percentage concentration values. The uses of 252Cf, 241Arn/Be and 239Pu/Be isotopic neutron sources for elemental investigation of: hematite, ilmenite, coal, petroleum, edible oils, phosphates and pollutant lake water samples have been mentioned.

  7. Nuclear structure far from stability: the neutron-rich 69-79Cu isotopes

    International Nuclear Information System (INIS)

    Far from stability, the nuclear structure that is predicted by the shell model is evolving. Old magic numbers disappear, while new ones appear. Our understanding of the underlying nuclear force that drives these changes is still incomplete. After a short overview across the nuclear chart, we discuss the strength functions of the shell-model orbitals in the neutron-rich copper isotopes towards the 78Ni doubly-magic nucleus. These were measured in a 72Zn(d,3He)71Cu proton pick-up reaction in inverse kinematics with a radioactive beam at the Ganil laboratory in France. We also present the latest results from a 80Zn(p,2p)79Cu knockout experiment at Riken in Japan, leading to selective population of hole states in 79Cu. Our findings show that the Z=28 shell gap in the neutron-rich copper isotopes is surprisingly steady against the addition of neutrons beyond N=40. (author)

  8. Nuclear and dosimetric features of an isotopic neutron source

    International Nuclear Information System (INIS)

    A multisphere neutron spectrometer was used to determine the features of a 239PuBe neutron source that is used to operate the ESFM-IPN Subcritical Reactor. To determine the source main features it was located a 100 cm from the spectrometer which was a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter polyethylene spheres. Count rates obtained with the spectrometer were unfolded using the NSDUAZ code and neutron spectrum, total fluence, and ambient dose equivalent were determined. A Monte Carlo calculation was carried out to estimate the spectrum and integral features being less than values obtained experimentally due to the presence of 241Pu in the Pu used to fabricate the source. Actual neutron yield and the mass fraction of 241Pu was estimated. - Highlights: • The neutron spectrum of a 239PuBe was measured. • With the spectrum integral features were determined. • It was estimated 0.23 w/o of 241Pu in the Pu used to make the source

  9. Composite delayed neutron energy spectra of fissionable isotopes

    International Nuclear Information System (INIS)

    Delayed neutron (DN) energy spectra spanning a range of 0.01-4.00 MeV have been measured for 235U, 238U and 239Pu. DN equilibrium spectra were also measured for all three nuclides. A helium jet transfer system was used to transport fission products to a low-background counting area. Beta-neutron correlations were used for background suppression and for energy determination by the neutron time-of-flight method. The 235U and 239Pu spectra show marked similarity, while those from the fast fission of 238U are considerably more energetic. DN six-group spectra for 235U, 238U and 239Pu have been deduced from these measurements using a constrained least-squares iterative method

  10. Isotope production for medical usage using fast neutron reactions

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Y.; Nagai, Y.; Kin, T. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan)] [and others

    2011-07-01

    {sup 99}Mo was produced by the {sup 100}Mo(n, 2n){sup 99}Mo reaction using 14-MeV neutrons from the D({sup 3}H, n){sup 4}He reaction at Fusion Neutronics Source Facility (FNS) at JAEA. A target of titanium oxide gel with molybdenum oxide was irradiated and used as the {sup 99m}Tc/{sup 99}Mo generator. The growth curve of 99mTc in the titanium gel target and the elution curve of {sup 99m}Tc from the {sup 99}Mo/{sup 99m}Tc generator were obtained. (orig.)

  11. Resonance neutron capture in the isotopes of titanium

    International Nuclear Information System (INIS)

    The neutron capture cross sections of 46Ti, 47Ti, 48Ti, 49Ti, 50Ti have been measured from 2.75 to 300 keV with approximately 0.2 per cent energy resolution. The reduced neutron and radiative widths of the s-wave resonance exhibit correlations which, with the exception of 47Ti, are consistent with the calculated magnitudes of the valence component, assuming that the radiative widths contain an additional uncorrelated part. In 47Ti, a significant correlation is observed for J=3- resonances, although the calculated valence component is small. (Author)

  12. First-forbidden β -decay rates, energy rates of β -delayed neutrons and probability of β -delayed neutron emissions for neutron-rich nickel isotopes

    International Nuclear Information System (INIS)

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β -decay rates, energy rate of β -delayed neutrons and probability of β -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow. (orig.)

  13. First-forbidden β -decay rates, energy rates of β -delayed neutrons and probability of β -delayed neutron emissions for neutron-rich nickel isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nabi, Jameel-Un; Iftikhar, Zafar [GIK Institute of Engineering Sciences and Technology, Faculty of Engineering Sciences, Khyber Pakhtunkhwa (Pakistan); Cakmak, Necla [Karabuek University, Department of Physics, Karabuek (Turkey)

    2016-01-15

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β -decay rates, energy rate of β -delayed neutrons and probability of β -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow. (orig.)

  14. Collinear resonant ionization spectroscopy for neutron rich copper isotopes

    CERN Multimedia

    This proposal aims to study the spins, magnetic moments and quadrupole moments of copper isotopes A=76-78. The information obtained from this experiment will provide an independent and more precise measurement of the magnetic moment of $^{77}$Cu and values for the spins and magnetic moments of $^{76,78}$Cu as well as the quadrupole moments of $^{76-78}$Cu.

  15. Isotope identification of Langkawi black sand using neutron activation analysis

    International Nuclear Information System (INIS)

    The Langkawi black sand has been analyzed using the method of neutron activation analysis (INAA). A total of 22 elements have been detected. Elements such as Mn, Cu, Cr, U and Th occur in high concentration. Prospect for future mineralization of these elements may be of economic interest. (author) 9 refs.; 1 tab

  16. Investigation of the single Particle Structure of the neutron-rich Sodium Isotopes $^{27-31}\\!$Na

    CERN Multimedia

    2002-01-01

    We propose to study the single particle structure of the neutron-rich isotopes $^{27-31}\\!$Na. These isotopes will be investigated via neutron pickup reactions in inverse kinematics on a deuterium and a beryllium target. Scattered beam particles and transfer products are detected in a position sensitive detector located around 0$^\\circ$. De-excitation $\\gamma$-rays emitted after an excited state has been populated will be registered by the MINIBALL Germanium array. The results will shed new light on the structure of the neutron-rich sodium isotopes and especially on the region of strong deformation around the N=20 nucleus $^{31}\\!$Na.

  17. Deformation and mixing of co-existing shapes in the neutron-deficient polonium isotopes

    CERN Document Server

    AUTHOR|(CDS)2078559; Huyse, Mark

    The neutron-deficient polonium isotopes, with only 2 protons outside the Z = 82 shell closure, are situated in an interesting region of the nuclear chart. In the neighboring lead (Z = 82) and mercury (Z = 80) isotopes, experimental and theoretical efforts identified evidence of shape coexistence. Shape coexistence is the remarkable phenomenon in which two or more distinct types of deformation occur in states of the same angular momentum and similar excitation energy in a nucleus. The neutron-deficient polonium isotopes have also been studied intensively, experimentally as well as theoretically. The closed neutron-shell nucleus 210Po (N = 126) manifests itself as a two-particle nucleus where most of the excited states can be explained by considering the degrees of freedom of the two valence protons outside of 208Pb. The near-constant behavior of the yrast 2+1 and 4+1 states in the isotopes with mass 200 ≤ A ≤ 208 can be explained by coupling the two valence protons to a vibrating lead core. 200Po seems to ...

  18. Microscopic description of fission in neutron-rich radium isotopes with the Gogny energy density functional

    Science.gov (United States)

    Rodrıguez-Guzmán, R.; Robledo, L. M.

    2016-01-01

    Mean-field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144≤ N≤ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well-developed third minimum along the fission paths of Ra nuclei is analyzed in terms of the energetics of the "fragments" defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and α -decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N=164 with a steady increase that makes heavier neutron-rich Ra isotopes stable against fission, diminishing the importance of fission recycling in the r-process.

  19. Microscopic description of fission in neutron-rich radium isotopes with the Gogny energy density functional

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Guzman, R. [Kuwait University, Physics Department, Kuwait (Kuwait); Robledo, L.M. [Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain)

    2016-01-15

    Mean-field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144 ≤ N ≤ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well-developed third minimum along the fission paths of Ra nuclei is analyzed in terms of the energetics of the ''fragments'' defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and α-decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N = 164 with a steady increase that makes heavier neutron-rich Ra isotopes stable against fission, diminishing the importance of fission recycling in the r-process. (orig.)

  20. Microscopic description of fission in neutron-rich radium isotopes with the Gogny energy density functional

    International Nuclear Information System (INIS)

    Mean-field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144 ≤ N ≤ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well-developed third minimum along the fission paths of Ra nuclei is analyzed in terms of the energetics of the ''fragments'' defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and α-decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N = 164 with a steady increase that makes heavier neutron-rich Ra isotopes stable against fission, diminishing the importance of fission recycling in the r-process. (orig.)

  1. Optimization of neutron flux distribution in Isotope Production Reactor

    International Nuclear Information System (INIS)

    In order to optimize the thermal neutrons flux distribution in a Radioisotope Production and Research Reactor, the influence of two reactor parameters was studied, namely theVmod/Vcomb ratio and the core volume. The reactor core is built with uranium oxide pellets (UO2) mounted in rod clusters, with an enrichment level of ∼3 %, similar to LIGHT WATER POWER REATOR (LWR) fuel elements. (author)

  2. New source-moderator geometry to improve performance of 252Cf and 241Am-Be source-based PGNAA setups

    International Nuclear Information System (INIS)

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups

  3. New source-moderator geometry to improve performance of {sup 252}Cf and {sup 241}Am-Be source-based PGNAA setups

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Abdelmonem, M.S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Misned, Ghada [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia); Al-Ghamdi, Hanan [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia)

    2006-06-15

    The gamma ray yield from a {sup 252}Cf and a {sup 241}Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the {sup 252}Cf and the {sup 241}Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a {sup 252}Cf and a {sup 241}Am-Be source-based PGNAA setups.

  4. β-delayed neutrons from very neutron-rich sodium and magnesium isotopes

    International Nuclear Information System (INIS)

    β-delayed neutron yields from 29Na to 34Na are measured with a high efficiency liquid scintillator neutron detector. Ph values and half-lives are deduced for 29Na to 34Na and 31Mg to 34Mg descendants

  5. Lead containing mainly isotope 208Pb. New neutron moderator, coolant and reflector for innovative nuclear reactors

    International Nuclear Information System (INIS)

    As a rule materials of small atomic weight (light and heavy water, graphite and so on) are used as neutron moderators and reflectors. A new very heavy atomic weight moderator is proposed - radiogenic lead consisting mainly of isotope 208Pb. It is characterized by extremely low neutron radioactive capture cross-section (0.23 mbarn for thermal neutrons, i.e. less than that for graphite and deuterium) and highest albedo of thermal neutrons. It is evaluated that use of the radiogenic lead enables a slowing of the chain reaction of prompt neutrons in a fast reactor. This can increase safety of the fast reactor as well reduce requirements pertaining to the technology of its fuel fabrication. Radiogenic lead with high 208Pb content as a liquid metal coolant of fast reactors helps to achieve a favorable (negative) coolant temperature reactivity coefficient. It is noteworthy that radiogenic lead with a large 208Pb content may be extracted from thorium (as well thorium-uranium) ores without isotope separation. This has been confirmed experimentally by an investigation performed at San Paula University, Brazil. (author)

  6. Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

    International Nuclear Information System (INIS)

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g7/2 5/2[413] neutron and g9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)

  7. Decay spectroscopy of neutron-rich rare-earth isotopes and collectivity around double midshell

    International Nuclear Information System (INIS)

    Neutron-rich rare-earth isotopes with A ≈ 170, which locate near the middle of the major shells for both proton and neutron between the doubly magic nuclei 132Sn and 208Pb, have been investigated by means of decay spectroscopy techniques at the RIBF facility at RIKEN. The nuclei of interest were produced by in-flight fission of a high-intensity 238U beam at 345 MeV/u. In this contribution, scientific motivations, the details of experimental procedures, and some prospects of the data analysis are reported

  8. Beta-decay properties of Zr and Mo neutron-rich isotopes

    CERN Document Server

    Sarriguren, P

    2010-01-01

    Gamow-Teller strength distributions, beta-decay half-lives, and beta-delayed neutron emission are investigated in neutron-rich Zr and Mo isotopes within a deformed quasiparticle random-phase approximation. The approach is based on a self-consistent Skyrme Hartree-Fock mean field with pairing correlations and residual separable particle-hole and particle-particle forces. Comparison with recent measurements of half-lives stresses the important role that nuclear deformation plays in the description of beta-decay properties in this mass region.

  9. Extrapolation of neutron-rich isotope cross-sections from projectile fragmentation

    OpenAIRE

    Mocko, M.; Tsang, M. B.; Z.Y. Sun; Andronenko, L.; Andronenko, M.; Delaunay, F.; Famiano, M.; Friedman, W. A.; Henzl, V.; Henzlova, D.; Hui, H.; Liu, X. D.; Lukyanov, S.; Lynch, W.G.; Rogers, A. M.

    2007-01-01

    Using the measured fragmentation cross sections produced from the 48Ca and 64Ni beams at 140 MeV per nucleon on 9Be and 181Ta targets, we find that the cross sections of unmeasured neutron rich nuclei can be extrapolated using a systematic trend involving the average binding energy. The extrapolated cross-sections will be very useful in planning experiments with neutron rich isotopes produced from projectile fragmentation. The proposed method is general and could be applied to other fragmenta...

  10. High-sensitivity measurement of 3He-4He isotopic ratios for ultracold neutron experiments

    Science.gov (United States)

    Mumm, H. P.; Huber, M. G.; Bauder, W.; Abrams, N.; Deibel, C. M.; Huffer, C. R.; Huffman, P. R.; Schelhammer, K. W.; Janssens, R.; Jiang, C. L.; Scott, R. H.; Pardo, R. C.; Rehm, K. E.; Vondrasek, R.; Swank, C. M.; O'Shaughnessy, C. M.; Paul, M.; Yang, L.

    2016-06-01

    Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of 3He to 4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10-14 level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of 3He/4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude.

  11. Separation and identification of new neutron-rich isotope 186Hf

    International Nuclear Information System (INIS)

    A new neutron-rich nuclide 186Hf is produced and identified by bombardment of natural tungsten samples with 60 MeV/u 18O beams using rapid radiochemical separation method and γ spectroscopic measurement technique for the first time. The half-life of the new neutron-rich isotope 186Hf is determined to be (2.6 +- 1.2) min by a radioactive series decay analytical program to fit the growth and decay curve. The chemical yield of element hafnium is more than 60% and the decontamination factor of tantalum is higher than 102 in the chemical separation

  12. Decay studies of the highly neutron-deficient indium isotopes

    International Nuclear Information System (INIS)

    An extension of the experimentally known nuclidic mass surface to nuclei far from the region of beta-stability is of fundamental interest in providing a better determination of the input parameters for the various nuclear mass formulae, allowing a more accurate prediction of the ultimate limits of nuclear stability. In addition, a study of the shape of the mass surface in the vicinity of the doubly-closed nuclide 100Sn provides initial information on the behavior of the shell closure to be expected when Z = N = 50. Experiments measuring the decay energies of 103105In by β-endpoint measurements are described with special attention focused on the development of a plastic scintillator β-telescope coupled to the on-line mass separator RAMA (Recoil Atom Mass Analyzer). An attempt to measure the β-endpoint energy of 102In is also briefly described. The experimentally determined decay energies and derived masses for 103105In are compared with the predictions of different mass models to identify which models are more successful in this region. Furthermore, the inclusion in these comparisons of the available data on the neutron-rich indium nuclei permits a systematic study of their ground state mass behavior as a function of the neutron number between the shell closures at N = 50 and N = 82. These analyses indicate that the binding energy of 103In is 1 MeV larger than predicted by the majority of the mass models. An examination of the Q/sub EC/ surface and the single- and two-neutron separation energies in the vicinity of 103105In is also performed to investigate further the deviation and other possible systematic variations in the mass surface in a model-independent way

  13. Decay studies of the highly neutron-deficient indium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, J.M.

    1982-02-01

    An extension of the experimentally known nuclidic mass surface to nuclei far from the region of beta-stability is of fundamental interest in providing a better determination of the input parameters for the various nuclear mass formulae, allowing a more accurate prediction of the ultimate limits of nuclear stability. In addition, a study of the shape of the mass surface in the vicinity of the doubly-closed nuclide /sup 100/Sn provides initial information on the behavior of the shell closure to be expected when Z = N = 50. Experiments measuring the decay energies of /sup 103/ /sup 105/In by ..beta..-endpoint measurements are described with special attention focused on the development of a plastic scintillator ..beta..-telescope coupled to the on-line mass separator RAMA (Recoil Atom Mass Analyzer). An attempt to measure the ..beta..-endpoint energy of /sup 102/In is also briefly described. The experimentally determined decay energies and derived masses for /sup 103/ /sup 105/In are compared with the predictions of different mass models to identify which models are more successful in this region. Furthermore, the inclusion in these comparisons of the available data on the neutron-rich indium nuclei permits a systematic study of their ground state mass behavior as a function of the neutron number between the shell closures at N = 50 and N = 82. These analyses indicate that the binding energy of /sup 103/In is 1 MeV larger than predicted by the majority of the mass models. An examination of the Q/sub EC/ surface and the single- and two-neutron separation energies in the vicinity of /sup 103/ /sup 105/In is also performed to investigate further the deviation and other possible systematic variations in the mass surface in a model-independent way.

  14. Evaluation of neutron induced reaction cross sections on Rh isotopes

    International Nuclear Information System (INIS)

    Evaluations of neutron nuclear data on 101,102,103,105Rh in the incident energies up to 20 MeV were performed, using theoretical nuclear reaction model code CCONE. The calculated cross sections of stable 103Rh are in good agreement with measured inelastic scattering, capture, (n, 2n), (n, p), (n, α) and (n, nα) reaction cross sections. The production cross section for the meta-state of 99Tc with half-life of 6.0 h was evaluated for the estimation of nuclear medicine use and resulted in 2.4 mb at a maximum. (author)

  15. Elastic recoil detection method using DT neutrons for hydrogen isotope analysis in fusion materials

    International Nuclear Information System (INIS)

    The Fusion Neutronics Source of Japan Atomic Energy Research Institute has started the study on the hydrogen isotope analysis for fusion components since 2002 on the basis of the techniques such as nuclear activation method, ion beam method and imaging plate method. In this study, we propose the elastic recoil detection analysis (NERDA) method using 14.1 MeV neutron beam to extend the analyzable depth of hydrogen isotopes analysis up to several hundreds micrometers. An experimental setup for NERDA was constructed and a proof-of-principle experiment was then made using a standard sample of deuterated polyethylene film containing a known concentration of deuterium with thickness of 100 μm. The depth resolution of the present condition was estimated to be 158 μm for the sample. (author)

  16. Structure in liquid KTl investigated by means of neutron diffraction using 205Tl isotope substitution

    International Nuclear Information System (INIS)

    In recent neutron diffraction measurements on liquid KTl, a prepeak was observed in the structure factor at a rather low value of the wave vector of 8 nm-1. It corresponds to a periodicity in real space of 0.93 nm. In solid KTl and K8Tl11, Tl clusters of, respectively, 6 and 11 atoms occur. It was concluded that parts of these clusters survive in the liquid state. In order to obtain more information on the structure of the clusters, we have performed an additional neutron diffraction experiment on D4 (ILL, Grenoble France) using 205Tl isotope substitution. From the additional data it is concluded that the prepeak occurs only in the Tl-Tl partial structure factor. Using RMC modelling of the isotopic data we are able to determine partial structure factors. The average Tl-Tl coordination number is 4.00.1. (orig.)

  17. Efficacy of cranking technique in the study of some neutron-deficient neodymium isotopes

    International Nuclear Information System (INIS)

    In the present work, the results of calculations on various nuclear structure quantities in even-even neutron-deficient 130-136Nd using Cranked Hatree-Fock Bogoliubov (CHFB) technique have been presented. The various nuclear structure quantities that have been calculated in 130-136Nd isotopes are the yrast spectra, subshell occupation probabilities of various valence orbits and intrinsic quadrupole moments. Besides this, a comparative study of the calculated yrast spectra with the available experimental data as well as with the results of calculations obtained by R.K. Bhat et al. using Variation After Projection (VAP) technique on the same neutron-deficient 130-136Nd isotopes has also been presented

  18. Isotopically-enriched gadolinium-157 oxysulfide scintillator screens for the high-resolution neutron imaging

    International Nuclear Information System (INIS)

    We demonstrate the feasibility of the production of isotopically-enriched gadolinium oxysulfide scintillator screens for the high spatial-resolution neutron imaging. Approximately 10 g of 157Gd2O2S:Tb was produced in the form of fine powder (particle size approximately 2 µm). The level of 157Gd enrichment was above 88%. Approximately 2.5 µm thick 157Gd2O2S:Tb scintillator screens were produced and tested for the absorption power and the light output. The results are compared to the reference screens based on natGd2O2S:Tb. The isotopically enriched screens provided increase by a factor of 3.8 and 3.6 for the absorption power and the light output, respectively. The potential of the scintillator screens based on 157Gd2O2S phosphor for the purpose of the (high-resolution) neutron imaging is discussed

  19. Microscopic study of neutron-rich dysprosium isotopes

    International Nuclear Information System (INIS)

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, γ and β bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of γ and β bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  20. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  1. Microscopic study of neutron-rich Dysprosium isotopes

    CERN Document Server

    Vargas, Carlos E; Lerma, Sergio; 10.1140/epja/i2013-13004-1

    2013-01-01

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry based models. Ground-state, gamma and beta-bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered whose free parameters, fixed for all members of the chain are used to fine tune the moment of inertia of rotational bands and the band-head of gamma and beta-bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study full chain of isotopes or isotones in the region with the present model.

  2. Cross section measurements of fast neutrons with isotopes of mercury

    International Nuclear Information System (INIS)

    Cross section were measured for the reactions 196Hg(n,2n)195Hgmg, 198Hg(n,2n)197Hgmg, 204Hg(n,2n)203Hg, 198Hg(n,p)198Aug and 199Hg(n,p)199Au over the neutron energy range of 7.6 - 12.5 MeV. Quasi monoenergetic neutrons were produced via the 2H(d,n)3He reaction using a deuterium gas target at the Julich variable energy compact cyclotron CV 28. Use was made of the activation technique in combination with high-resolution HPGe-detector gamma ray spectroscopy. All the data were measured for the first time over the investigated energy range. The transition from the present low- energy data to the literature data around 14 MeV is generally good. Nuclear model calculations using the codes STAPRE and EMPIRE-2.19 which employ the statistical and precompound model formalisms were undertaken to describe the formation of both the isomeric and ground states of the products. The total reaction cross section of a particular channel is reproduced fairly well by the model calculations, with STAPRE giving slightly better results

  3. Decay of neutron-rich Ga isotopes near N=50 at PARRNe

    International Nuclear Information System (INIS)

    The PARRNe facility has been used to produce neutron-rich isotopes 83,84Ga by the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time

  4. Neutron-rich In and Cd isotopes close to the doubly-magic $^{132}Sn$

    OpenAIRE

    Scherillo, A.; Genevey, J.; Pinston, J.A.; Covello, A; Faust, H.; Gargano, A.; R. Orlandi; Simpson, G.S.; Tsekhanovich, I.

    2005-01-01

    Microsecond isomers in the In and Cd isotopes, in the mass range A = 123 to 130, were investigated at the ILL reactor, Grenoble, using the LOHENGRIN mass spectrometer, through thermal-neutron induced fission reactions of Pu targets. The level schemes of the odd-mass $^{123-129}$In are reported. A shell-model study of the heaviest In and Cd nuclei was performed using a realistic interaction derived from the CD-Bonn nucleon-nucleon potential

  5. Saturation of Deformation and Identical Bands in Very-Neutron Rich Sr Isotopes

    CERN Multimedia

    2002-01-01

    The present proposal aims at establishing nuclear properties in an isotopic chain showing unique features. These features include the saturation of ground state deformation at its onset and the existence of ground state identical bands in neighbouring nuclei with the same deformation. The measurements should help to elucidate the role played by the proton-neutron residual interaction between orbitals with large spatial overlap, i.e. $\\pi g _{9/2} \

  6. Laser Spectroscopy Study on the Neutron-Rich and Neutron-Deficient Te Isotopes

    CERN Multimedia

    2002-01-01

    We propose to perform laser spectroscopy measurements on the Te isotopes. This will give access to fundamental properties of the ground and rather long-lived isomeric states such as the change in the mean square charge radius ($\\delta\\langle$r$^2_c\\rangle$) and the nuclear moments. For these medium-mass isotopes, at this moment the optical resolution obtained with RILIS is not high enough to perform isotope shift measurements. Thus we will use the COMPLIS experimental setup which allows Resonant Ionization Spectroscopy (RIS) on laser desorbed atoms. The 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{3}$S$_{1}$ and 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{5}$S$_{2}$ optical transitions have been used to perform, on the stable Te isotopes, the tests required by the INTC committee. For this purpose stable-ion sources have been built and Te isotopes have been delivered as stable beams by the injector coupled to the COMPLIS setup. ISOLDE offers the opportunity for studying the Te isotope series over a ...

  7. Fusion of neutron rich oxygen isotopes in the crust of accreting neutron stars

    CERN Document Server

    Horowitz, C J; Berry, D K

    2007-01-01

    Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge $Z$. Nuclei with $Z\\le 6$ can fuse at low densities in a liquid ocean. However, nuclei with $Z=8$ or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the $S$ factor for fusion reactions of neutron rich nuclei including $^{24}$O + $^{24}$O and $^{28}$Ne + $^{28}$Ne. We use a simple barrier penetration model. The $S$ factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in $S$ should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase sep...

  8. Estimate of production of medical isotopes by photo-neutron reaction at the Canadian Light Source

    International Nuclear Information System (INIS)

    In contrast to conventional bremsstrahlung photon beam sources, laser backscatter photon sources at electron synchrotrons provide the capability to selectively tune photons to energies of interest. This feature, coupled with the ubiquitous giant dipole resonance excitations of atomic nuclei, promises a fertile method of nuclear isotope production. In this article, we present the results of simulations of production of the medical/industrial isotopes 196Au, 192Ir and 99Mo by (γ,n) reactions. We employ FLUKA Monte Carlo code along with the simulated photon flux for a beamline at the Canadian Light Source in conjunction with a CO2 laser system. -- Highlights: •We estimate production of medical isotopes by photo-neutron reaction. •Recently developed simulation code for generating laser backscattering photons at the CLS storage ring is described and used. •We describe the preliminary Monte Carlo simulations (using FLUKA code) for the production of 99Mo, 196Au and 192Ir isotopes. •The simulations demonstrate that the medical isotopes 99Mo, 192Ir and 196Au are the main products of photonuclear reaction on 100Mo, 193Ir and 197Au targets. •The present results agree with the evaluated and observed radioactive isotope production rates in RPIT experiment

  9. Decay studies of neutron deficient rare earth isotopes with OASIS

    Energy Technology Data Exchange (ETDEWEB)

    Gilat, J.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.; Firestone, R.B.

    1987-09-01

    We report results on the decay of /sup 124/Pr, /sup 124,125/Ce, /sup 124,125/La, /sup 134-136/Eu, /sup 134-136/Sm, /sup 134-136/Pm, /sup 144/Ho, /sup 141,142,144/Dy, /sup 140,141,142,144/Tb, /sup 140-142/Gd, and /sup 140-142/Eu, produced by /sup 92/Mo(H.I.,xpyn) reactions at the Berkeley SuperHILAC, and studied with the OASIS on-line mass separator facility. Half-lives, delayed proton branching ratios, ..gamma..-ray energies and intensities, partial decay schemes and several J/sup ..pi../ assignments are presented. Level systematics of the even mass Nd and Sm isotopes and of the nu h/sub 11/2/ - nu s/sub 1/2/ isomers for N = 77 are discussed.

  10. Decay studies of neutron deficient rare earth isotopes with OASIS

    International Nuclear Information System (INIS)

    We report results on the decay of 124Pr, /sup 124,125/Ce, /sup 124,125/La, /sup 134-136/Eu, /sup 134-136/Sm, /sup 134-136/Pm, 144Ho, /sup 141,142,144/Dy, /sup 140,141,142,144/Tb, /sup 140-142/Gd, and /sup 140-142/Eu, produced by 92Mo(H.I.,xpyn) reactions at the Berkeley SuperHILAC, and studied with the OASIS on-line mass separator facility. Half-lives, delayed proton branching ratios, γ-ray energies and intensities, partial decay schemes and several J/sup π/ assignments are presented. Level systematics of the even mass Nd and Sm isotopes and of the nu h/sub 11/2/ - nu s/sub 1/2/ isomers for N = 77 are discussed

  11. Realistic shell-model calculations for neutron deficient Sn isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, F.; Coraggio, L.; Covello, A.; Gargano, A.; Kuo, T.T.; Li, Z.B.; Porrino, A. [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II]|[Istituto Nazionale di Fisica Nucleare, Mostra d`Oltremare, Pad. 20, 80125 Napoli (Italy)]|[Department of Physics, SUNY, Stony Brook, New York 11794 (United States)

    1996-10-01

    We have performed shell-model calculations for {sup 102,103,104,105}Sn using two realistic effective interactions derived from the Bonn A and Paris nucleon-nucleon potentials, respectively. From the comparison of the calculated spectra of {sup 104}Sn and {sup 105}Sn with the experimental ones it turns out that the best agreement is obtained with the weaker tensor force potential (Bonn A). This agreement appears to be significantly better than for other nuclear regions, such as the {ital sd} shell, and thus encourages use of modern realistic potentials in shell-model calculations for medium- and heavy-mass nuclei. In addition, it supports confidence in our predictions of the spectra of the hitherto unknown isotopes {sup 102}Sn and {sup 103}Sn. {copyright} {ital 1996 The American Physical Society.}

  12. Realistic shell-model calculations for neutron deficient Sn isotopes

    International Nuclear Information System (INIS)

    We have performed shell-model calculations for 102,103,104,105Sn using two realistic effective interactions derived from the Bonn A and Paris nucleon-nucleon potentials, respectively. From the comparison of the calculated spectra of 104Sn and 105Sn with the experimental ones it turns out that the best agreement is obtained with the weaker tensor force potential (Bonn A). This agreement appears to be significantly better than for other nuclear regions, such as the sd shell, and thus encourages use of modern realistic potentials in shell-model calculations for medium- and heavy-mass nuclei. In addition, it supports confidence in our predictions of the spectra of the hitherto unknown isotopes 102Sn and 103Sn. copyright 1996 The American Physical Society

  13. E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

    International Nuclear Information System (INIS)

    High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following 48Ca + 208Pb, 48Ca + 238U, and 64Ni + 238U reactions. By exploiting delayedand cross-coincidence techniques, level schemes have been delineated in odd 119–125Sn isotopes. Particular attention was paid to the occurrence of 19/2+ and 23/2+ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudes for the seniority ν = 2 and 3, 10+ and 27/2– isomers in even- and odd-Sn isotopes, respectively

  14. Coulomb Excitation of Neutron Deficient Sn-Isotopes using REX-ISOLDE

    CERN Multimedia

    Di julio, D D; Kownacki, J M; Marechal, F; Andreoiu, C; Siem, S; Perrot, F; Van duppen, P L E; Napiorkowski, P J; Iwanicki, J S

    2002-01-01

    It is proposed to study the evolution of the reduced transition probabilities, B(E2; 0$^{+} \\rightarrow$ 2$^{+}$), for neutron deficient Sn isotopes by Coulomb excitation in inverse kinematics using REX-ISOLDE and the MINIBALL detector array. Measurements of the reduced transition matrix element for the transition between the ground state and the first excited 2$^{+}$ state in light even-even Sn isotopes provide a means to study e.g. core polarization effects in the $^{100}$Sn core. Previous attempts to measure this quantity have been carried out using the decay of isomeric states populated in fusion evaporation reactions. We thus propose to utilize the unique opportunity provided by REX-ISOLDE, after the energy upgrade to 3.1 MeV/u, to use the more model-independent approach of Coulomb excitation to measure this quantity in a number of isotopes in this region.

  15. Determination of integrated neutron flux by the measurement of the isotopic ratios of cadmium and gadolinium

    International Nuclear Information System (INIS)

    In this work, the possibility of the indirect determination of the integrated neutron flux, through the change of isotopic ratios of cadmium and gadolinium was investigated. The samples of cadmium we/e gadolinium were irradiated in the IEA-Rl reactor. These elements were chosen because they have high thermal neutron absorption cross section which permit the change in the isotopic composition during a short irradiation time to be measured accurately. The isotopic ratios were measured with a thermionic mass spectrometer the silica-gel technique and arrangement with single filament were used for the cadmium analysis, where as the oxi - reduction technique and arrangement with double filaments were used for gadolinium analysis. The mass fractionation effects for cadmium and gadolinium were corrected respectively by the exponential and potential expansion of the isotopic fractionation factor per atomic mass unit. The flux values supplied by the Centro de Operacao e Utilizacao do Reator de Pesquisas do IPEN were extrapolated. These values and the integrated flux values obtained experimentally were compared. (author)

  16. Shell Model Embedded in the Continuum for Binding Systematics in Neutron-Rich Isotopes of Oxygen and Fluor

    CERN Document Server

    Luo, Y; Ploszajczak, M; Michel, N

    2002-01-01

    Continuum coupling correction to binding energies in the neutron rich oxygen and fluorine isotopes is studied using the Shell Model Embedded in the Continuum. We discuss the importance of different effects, such as the position of one-neutron emission threshold, the effective interaction or the number of valence particles on the magnitude of this correction.

  17. Investigations of neutron characteristics for salt blanket models; integral fission cross section measurements of neptunium, plutonium, americium and curium isotopes

    International Nuclear Information System (INIS)

    Neutron characteristics of salt blanket micromodels containing eutectic mixtures of sodium, zirconium, and uranium fluorides were measured on FKBN-2M, BIGR and MAKET facilities. The effective fission cross sections of neptunium, plutonium, americium, and curium isotopes were measured on the neutron spectra formed by micromodels. (author)

  18. Measurements of absolute γ-ray intensities in the decays of very neutron rich isotopes of Cd and In

    International Nuclear Information System (INIS)

    The half lives and the γ-ray branching ratios of neutron rich Cd and In isotopes have been investigated by simultaneous measurements of β- and γ-ray spectra. The results presented contain information on 21 different β-decaying isotopes or isomers of Cd and In in the mass region A=123-129. Four previously unknown or little known isotopes of Cd are reliably characterized for the first time. (orig.)

  19. Statistics of dose received by occupational personnel from neutron sources - 10 year study

    International Nuclear Information System (INIS)

    Personnel Monitoring Section, BARC conducts countrywide fast neutron personnel monitoring using CR-39 solid state nuclear track detector. About 1350 personnel working in a wide range of situations are being monitored presently for fast neutrons. Nearly 50% of the personnel monitored are working with isotopic neutron sources e.g. 241Am-Be (up to 740 GBq source strength) in industry and the remaining are connected with nuclear fuel cycle. This paper describes our experience with this personnel neutron monitor and presents the analysis of the neutron equivalent doses received by personnel working in industry during last 10 years and its contribution as compared to total equivalent dose. (author)

  20. Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

    International Nuclear Information System (INIS)

    Beta-delayed neutron (βn) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material β-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure βn-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 β-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 β-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of β-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and theoretical models

  1. Fusion of neutron rich oxygen isotopes in the crust of accreting neutron stars

    OpenAIRE

    Horowitz, C. J.; Dussan, H.; Berry, D. K.

    2007-01-01

    Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge $Z$. Nuclei with $Z\\le 6$ can fuse at low densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the $S$ ...

  2. Fast neutron capture in actinide isotopes: recent results from Karlsruhe

    International Nuclear Information System (INIS)

    Capture gamma-ray spectra of 241Am, 240Pu, 242Pu 238U and 197Au were calculated in the framework of the spherical optical model and the statistical model. These spectra were used to correct experimental data for the capture cross sections of 240242Pu and 241Am from relative measurements using a Moxon Rae-detector with graphite converter and 197Au as well as 238U as standards. This correction is required to take into account that the detector efficiency is not exactly proportional to gamma-ray energy. The resulting correction factors proved to be negligible for measurements relative to 238U, whereas they are approx. 3% if gold is used as a standard. The capture cross section of 243Am has been measured in the energy range 10 to 250 keV using kinematically collimated neutrons from the 7Li(p,n) and T(p,n) reaction. The samples are positioned at flight paths of 5 to 7 cm and gold was used as a standard. Capture events were detected by two Moxon-Rae detectors with graphite and bismuth-graphite converters shielded by 0.5 to 2 cm of lead. Fission events were detected by a NE213 liquid scintillator. The present status of the experiment and some preliminary results will be presented

  3. Comparison of statistical model calculations for stable isotope neutron capture

    Science.gov (United States)

    Beard, M.; Uberseder, E.; Crowter, R.; Wiescher, M.

    2014-09-01

    It is a well-observed result that different nuclear input models sensitively affect Hauser-Feshbach (HF) cross-section calculations. Less well-known, however, are the effects on calculations originating from nonmodel aspects, such as experimental data truncation and transmission function energy binning, as well as code-dependent aspects, such as the definition of level-density matching energy and the inclusion of shell correction terms in the level-density parameter. To investigate these aspects, Maxwellian-averaged neutron capture cross sections (MACS) at 30 keV have been calculated using the well-established statistical Hauser-Feshbach model codes talys and non-smoker for approximately 340 nuclei. For the same nuclei, MACS predictions have also been obtained using two new HF codes, cigar and sapphire. Details of these two codes, which have been developed to contain an overlapping set of identically implemented nuclear physics input models, are presented. It is generally accepted that HF calculations are valid to within a factor of 3. It was found that this factor is dependent on both model and nonmodel details, such as the coarseness of the transmission function energy binning and data truncation, as well as variances in details regarding the implementation of level-density parameter, backshift, matching energy, and giant dipole strength function parameters.

  4. Production of unknown neutron-rich isotopes in 238U collisions at near-barrier energy

    Science.gov (United States)

    Zhao, Kai; Li, Zhuxia; Zhang, Yingxun; Wang, Ning; Li, Qingfeng; Shen, Caiwan; Wang, Yongjia; Wu, Xizhen

    2016-08-01

    The production cross sections for primary and residual fragments with charge number from Z =70 to 120 produced in the collision of 238U at 7.0 MeV/nucleon are calculated by the improved quantum molecular dynamics (ImQMD) model incorporated with the statistical evaporation model (hivap code). The calculation results predict that about 60 unknown neutron-rich isotopes from elements Ra (Z =88 ) to Db (Z =105 ) can be produced with the production cross sections above the lower bound of 10-8 mb in this reaction. And almost all of the unknown neutron-rich isotopes are emitted at the laboratory angles θlab≤60°. Two cases, i.e., the production of the unknown uranium isotopes with A ≥244 and that of rutherfordium with A ≥269 , are investigated to understand the production mechanism of unknown neutron-rich isotopes. It is found that for the former case the collision time between two uranium nuclei is shorter and the primary fragments producing the residues have smaller excitation energies of ≤30 MeV and the outgoing angles of those residues cover a range of 30°-60°. For the latter case, a longer collision time is needed for a large number of nucleons being transferred and thus it results in higher excitation energies and smaller outgoing angles of primary fragments, and eventually results in a very small production cross section for the residues of Rf with A ≥269 which have a small interval of outgoing angles of θlab=40°-50°.

  5. Scission neutrons for U, Pu, Cm, and Cf isotopes: Relative multiplicities calculated in the sudden limit

    Science.gov (United States)

    Capote, R.; Carjan, N.; Chiba, S.

    2016-02-01

    The multiplicities of scission neutrons νs c are calculated for series of U, Pu, Cm, and Cf isotopes assuming a sudden transition between two different nuclear configurations (αi→αf ): one just before the neck rupture and one immediately after the disappearance of the neck. This calculation requires only the knowledge of the corresponding two sets of neutron eigenstates. The nuclear shapes around the scission point are described in terms of Cassinian ovals with only two parameters: α (that positions the shape with respect to the zero-neck shape) and α1 (that defines the mass asymmetry). Based on these shapes, a neutron mean field of the Woods-Saxon type is constructed using two prescriptions to calculate the distance to the nuclear surface. The accent in the present work is put on the dependence of νs c on the neutron number Nf of the fissioning nucleus and on the mass asymmetry AL/AH of the primary fission fragments. The relative dependence of these multiplicities, averaged over the mass yields, , are finally compared with existing experimental data on prompt fission neutrons .

  6. ZIRCONIUM—HAFNIUM ISOTOPE EVIDENCE FROM METEORITES FOR THE DECOUPLED SYNTHESIS OF LIGHT AND HEAVY NEUTRON-RICH NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Akram, W.; Schönbächler, M. [School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Sprung, P. [Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Vogel, N. [Institute for Geochemistry and Petrology, ETH, Clausiusstrasse 25, 8092 Zürich (Switzerland)

    2013-11-10

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (≤1ε in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (∼2ε). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ≤ 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ☉}) SNII.

  7. Double-neutron capture reaction and natural abundance of 183W, 195Pt, and 199Hg isotopes

    International Nuclear Information System (INIS)

    The database for neutron cross sections is well developed over the nuclide chart for stable isotopes and not as much for the radioactive species. Double-neutron capture experiments could be productive to supply more data. Time-integrated mean flux of slow neutrons reaches a value of 2.3·1012 cm-2·s-1 at the irradiation port near the active zone of the IBR-2 pulsed reactor of JINR. This is enough to detect the double-neutron capture products by the activation method. A high capture cross section is deduced in the present experiment for intermediate radioactive 182Ta and 194Ir target nuclides. Together with the known one for 198Au, these values may prove an essential role of double-neutron capture process for nucleosynthesis of 183W, 195Pt, and 199Hg isotopes at stellar conditions.

  8. Double-neutron capture reaction and natural abundance of 183W, 195Pt and 199Hg isotopes

    Science.gov (United States)

    Karamian, S. A.; Aksenov, N. V.; Bozhikov, G. A.

    2016-06-01

    There are much data on neutron cross sections over the chart of nuclides for stable isotopes and not as much for the radioactive ones. Double neutron capture experiments could be fruitful to provide more data. Time-integrated mean flux of slow neutrons reaches the value of 2.3-1012 n/cm2 s at the irradiation port near the active zone of the IBR-2 pulsed reactor of JINR. This is enough to detect the double neutron capture products by the activation method. A high capture cross section is obtained in the present experiment for intermediate radioactive 182Ta and 194Ir target nuclides. Together with the known data for 198Au, these values may prove an essential role of double neutron capture process for nucleosynthesis of 183W, 195Pt and 199Hg isotopes at stellar conditions.

  9. $\\beta$-delayed neutron spectroscopy of $^{130-132}$ Cd isotopes with the ISOLDE decay station and the VANDLE array

    CERN Multimedia

    We propose to use the new ISOLDE decay station and the neutron detector VANDLE to measure the $\\beta$-delayed neutron emission of N=82-84 $^{130-132}$Cd isotopes. The large delayed neutron emission probability observed in a previous ISOLDE measurement [M. Hannawald et al., Phys. Rev. C62, 054301 (2000)] is indicative of the Gamow-Teller transitions due to the decay of deep core neutrons. Core Gamow-Teller decay has been experimentally proven in the $^{78}$Ni region for the N>50 nuclei using the VANDLE array. The spectrocopic measurement of delayed neutron emission along the cadmium isotopic chain will allow us to track the evolution of the single particle states and the shell gap.

  10. The neutron capture cross section of the ${s}$-process branch point isotope $^{63}$Ni

    CERN Multimedia

    Neutron capture nucleosynthesis in massive stars plays an important role in Galactic chemical evolution as well as for the analysis of abundance patterns in very old metal-poor halo stars. The so-called weak ${s}$-process component, which is responsible for most of the ${s}$ abundances between Fe and Sr, turned out to be very sensitive to the stellar neutron capture cross sections in this mass region and, in particular, of isotopes near the seed distribution around Fe. In this context, the unstable isotope $^{63}$Ni is of particular interest because it represents the first branching point in the reaction path of the ${s}$-process. We propose to measure this cross section at n_TOF from thermal energies up to 500 keV, covering the entire range of astrophysical interest. These data are needed to replace uncertain theoretical predicitons by first experimental information to understand the consequences of the $^{63}$Ni branching for the abundance pattern of the subsequent isotopes, especially for $^{63}$Cu and $^{...

  11. Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

    CERN Multimedia

    Schweikhard, L C; Savreux, R P; Hager, U D K; Beck, D; Blaum, K

    2007-01-01

    We propose to perform mass measurements followed by $\\beta$- and $\\gamma$-decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range.\\\\ To reach the isobaric purity, the experiments will be p...

  12. Evolution of Single Particle and Collective properties in the Neutron-Rich Mg Isotopes

    CERN Multimedia

    Reiter, P; Wiens, A; Fitting, J; Lauer, M; Van duppen, P L E; Finke, F

    2002-01-01

    We propose to study the single particle and collective properties of the neutron-rich Mg isotopes in transfer reactions and Coulomb excitation using REX-ISOLDE and MINIBALL. From the Coulomb excitation measurement precise and largely model independent B( E2 ; 0$^{+}_{g.s.}\\rightarrow$ 2$^{+}_{1}$ ) will be determined for the even-even isotopes. For the odd isotopes the distribution of the E2 strength over a few low-lying states will be measured. The sign of the M1/E2 mixing ratio, extracted from angular distributions, is characteristic of the sign of the deformation, as is the resulting level scheme. The neutron-pickup channel in the transfer reactions will allow for a determination of the single particle properties (spin, parity, spectroscopic factors) of these nuclei. This information will give new insights in changes of nuclear structure in the vicinity of the island of deformation around $^{32}$Mg. A total of 24 shifts of REX beam time is requested.

  13. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    International Nuclear Information System (INIS)

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,21+→01+) values in 74-80Zn, B(E2,41+→21+) values in 74,76Zn and the determination of the energy of the first excited 21+ states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, including a recent empirical residual interaction constructed to describe the present experimental data up to 2004 in this region of the nuclear chart

  14. Photon strength functions in Gd isotopes studied from radiative capture of resonance neutrons

    Directory of Open Access Journals (Sweden)

    Kroll J.

    2014-04-01

    Full Text Available The experimental spectra of γ rays following radiative neutron capture on isolated resonances of stable 152,154–158Gd targets were measured by the DANCE calorimeter installed at the Los Alamos Neutron Scattering Center in New Mexico, USA. These spectra were analyzed within the extreme statistical model to get new information on the photon strength functions. Special emphasis was put on study of the scissors vibrational mode present in these isotopes. Our data show that the scissors-mode resonances are built not only on the ground states but also on the excited levels of all studied Gd isotopes. The scissors mode strength observed in 157,159Gd products is significantly higher than in neighboring even-even nuclei 156,158Gd. Such a difference indicates the existence of an odd-even effect in the scissors mode strength. Moreover, there exists no universal parameter-free model of the electric dipole photon strength function describing the experimental data in all of the Gd isotopes studied. The results for the scissors mode are compared with the (γ, γ′ data for the ground-state transitions and with the results from 3He-induced reactions.

  15. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    CERN Document Server

    Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M

    2009-01-01

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...

  16. Enhanced collectivity of gamma vibration in neutron-rich Dy isotopes with N=108 - 110

    CERN Document Server

    Yoshida, Kenichi

    2016-01-01

    Background: The $\\gamma$ vibrational mode of excitation is an acknowledged collective mode in deformed nuclei. The collectivity depends on the details of the shell structure around the Fermi levels, in particular the presence of the orbitals that have the enhanced transition matrix elements of the non-axial quadrupole excitation. Quite recently, a sudden decrease in the excitation energy of the $\\gamma$ vibration was observed at RIKEN RIBF for the neutron-rich Dy isotopes at $N=106$. Purpose: In the present work, by studying systematically the microscopic structure of the $\\gamma$ vibration in the neutron-rich Dy isotopes with $N=98-114$, we try to understand the mechanism of the observed softening. Methods: The low-frequency modes of excitation in the neutron-rich rare-earth nuclei are described based on nuclear density-functional theory. We employ the Skyrme energy-density functionals (EDF) in the Hartree-Fock-Bogoliubov calculation for the ground states and in the Quasiparticle Random-Phase Approximation (...

  17. Microscopic description of fission in neutron-rich Radium isotopes with the Gogny energy density functional

    CERN Document Server

    Rodriguez-Guzman, R R

    2015-01-01

    Mean field calculations, based on the D1S, D1N and D1M parametrizations of the Gogny energy density functional, have been carried out to obtain the potential energy surfaces relevant to fission in several Ra isotopes with the neutron number 144 $\\le$ N $\\le$ 176. Inner and outer barrier heights as well as first and second isomer excitation energies are given. The existence of a well developed third minimum along the fission paths of Ra nuclei, is analyzed in terms of the energetics of the "fragments" defining such elongated configuration. The masses and charges of the fission fragments are studied as functions of the neutron number in the parent Ra isotope. The comparison between fission and $\\alpha$-decay half-lives, reveals that the former becomes faster for increasing neutron numbers. Though there exists a strong variance of the results with respect to the parameters used in the computation of the spontaneous fission rate, a change in tendency is observed at N=164 with a steady increase that makes heavier ...

  18. Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

    International Nuclear Information System (INIS)

    Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine Shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 +-2cm, corresponding to a preatmospheric mass of 28 +- 13 kg. U-concentrations measurements indicate that phosphates have concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear cut excess in 150Sm, enable us to derive meaningful upper limits to thermal neutron fluences of 2 to 3x1015n/cm2, during a possible regolith irradiation. These limits are consistent with that required to explain the track data and also enable us to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith. (Author)

  19. Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

    International Nuclear Information System (INIS)

    Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12+-2 cm, corresponding to a preatmospheric mass of 28+-13 kg. Phosphates have U-concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear cut excess in 150Sm, enable us to derive meaningful upper limits to thermal neutron fluences of 2 to 3x1015 n/cm2, during a possible regolith irradiation. These limits are consistent with the track data and also enable us to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith. (author)

  20. Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

    Science.gov (United States)

    Rajan, R. S.; Lugmair, G.; Tamhane, A. S.; Poupeau, G.

    1986-01-01

    Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 + or - 2 cm, corresponding to a preatmospheric mass of 28 + or - 13 kg. Phosphates have U concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron-induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear-cut excess in Sm-150, make it possible to derive meaningful upper limits to thermal neutron fluences of 2 to 3 x 10 to the 15th n/sq cm, during a possible regolith irradiation. These limits are consistent with the track data and also make it possible to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith.

  1. Neutron capture cross-sections of krypton isotopes and their astrophysical implications

    International Nuclear Information System (INIS)

    For the measurement of neutron capture cross sections of noble gases a new experimental technique was developed using high pressure gas targets. By this technique, measurements on five krypton samples with different isotopic composition were performed by which the capture and the total cross sections between 5 and 200 keV were determined in the same experiment with good statistical accuracy. Values of Maxwellian averaged capture cross sections at 30 keV could be derived for the stable isotopes of krypton, as they are required for a quantitative understanding of the s-process of nucleosynthesis. From the systematics of this s-process it was possible to determine the original abundance of krypton in the solar system. The branching of the s-process at Se-79 allowed to determine the temperature of the s-process. A value of kT = 35 keV is adopted by this calculation. (orig.) 891 KBE/orig. 892 HIS

  2. Quasi-free scattering of neutron-deficient carbon isotopes in inverse kinematics

    International Nuclear Information System (INIS)

    Quasi-free scattering reactions are a valuable tool to study single-particle properties of nuclei. Particularly, they can be used to study absolute spectroscopic factors which appear to be quenched for deeply bound nucleons. Quasi-free scattering of relativistic neutron-deficient isotopes has been studied in inverse kinematics during experiment S393 at the R3B-LAND setup. In this experiment, a radioactive beam coming from the fragment separator FRS was used to induce secondary reactions with a CH2 target. The incoming beam as well as the reaction products were detected in kinematically complete measurements. Results for the (p,2p) and (p,pn) reactions on 10,11C are shown and compared to results obtained for knockout reactions from these isotopes.

  3. Study of the nuclear matter distribution in neutron-rich Li isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dobrovolsky, A.V. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation)]. E-mail: dobrov@pnpi.spb.ru; Alkhazov, G.D. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Andronenko, M.N. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Bauchet, A. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Egelhof, P. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Fritz, S. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Geissel, H. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Gross, C. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Khanzadeev, A.V. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Korolev, G.A. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Kraus, G. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Lobodenko, A.A. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Muenzenberg, G. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Mutterer, M. [Institut fuer Kernphysik (IKP), TU-Darmstadt, 64289 Darmstadt (Germany); Neumaier, S.R. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Institut fuer Kernphysik (IKP), TU-Darmstadt, 64289 Darmstadt (Germany); Schaefer, T. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Scheidenberger, C. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Seliverstov, D.M. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Timofeev, N.A. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation); Vorobyov, A.A.; Yatsoura, V.I. [Petersburg Nuclear Physics Institute (PNPI), 188300 Gatchina (Russian Federation)

    2006-02-20

    The differential cross sections for small-angle proton elastic scattering on the {sup 6,8,9,11}Li nuclei at energies near 700 MeV/nucleon were measured in inverse kinematics using secondary nuclear beams at GSI Darmstadt. The hydrogen-filled ionization chamber IKAR was employed as target and recoil proton detector. For determining the nuclear matter radii and radial matter distributions, the measured cross sections have been analysed with the aid of the Glauber multiple-scattering theory. The nuclear matter distribution deduced for {sup 11}Li exhibits a very pronounced halo structure, the matter radius of {sup 11}Li being significantly larger than those of the {sup 6,8,9}Li isotopes. The data on {sup 8,9}Li are consistent with the existence of sizable neutron skins in these nuclei. The obtained data allow for a test of various theoretical model calculations of the structure of the studied neutron-rich nuclei.

  4. Actinide isotopes compositions and neutrons emission rate calculations for irradiated research reactors fuel

    International Nuclear Information System (INIS)

    the availability of burn-up data is an essential first step in any systematic approach to the enhancement of safety, economics and performance of research reactors. A computer program has been designed to solve the system of equations describing the depletion, decay and production of uranium, plutonium and transplutonium nuclides. monte Carlo code was used to calculate the effective one group microscopic cross sections averaged over ETRR-1 fuel cell. the compositions of actinide isotopes, burn-up and neutrons emission rate have been calculated as a function of irradiation time and cooling time. results indicate that the amount of plutonium produced and neutrons emission rate are strongly dependent on the fuel burn-up

  5. Collectivity in light zirconium isotopes: Evolution with neutron number and angular momentum

    International Nuclear Information System (INIS)

    Considerable data have recently been collected on light zirconium isotopes. We present new measurements on 84Zr and some unpublished results on 82Zr. We have performed calculations on 82,84,86Zr using an extension to the IBM which allows a collective core to couple to up to four unpaired fermions (two broken pairs). The role of vibrational collectivity is clear in the N=44 and N=46 nuclei, but collective rotation becomes the dominant mode below N=44. The relative positions of the neutron and proton Fermi surfaces are crucial in determining the complexity of the decay path down the yrast states, being dominated by proton configurations for N≤44 but showing strong competition between neutron and proton structures when N>44

  6. Experimental studies of the medical isotopes production using spallation neutrons generated in massive uranium target

    International Nuclear Information System (INIS)

    The possibility of medical radionuclides 64,67Cu production in spallation-neutron spectrum in natZn (n, x) reactions has been studied. Experiments were performed on a massive uranium target (mass of natural uranium 512 kg) at the accelerators ''Nuclotron'' and ''Phasotron'' JINR, Dubna. Spallation neutron spectrum averaged cross sections for the natZn(n, x)67Cu and natZn(n, x)64Cu reactions were estimated: 0.42 (6) mb and 8.1 (12) mb, respectively. The MCNPX simulation of 67,64Cu production and definition of the theoretical limit of the specific activity of 67,64Cu by irradiation of zinc and zinc enriched by the 68 isotope were performed.

  7. Neutronic transmutation of transuranium isotopes in a fast neutron power reactor

    International Nuclear Information System (INIS)

    Starting from the theoretical basis of the transmutation, calculations of homogeneous recycling and heterogeneous configurations for a 1200 MWe LMFBR are executed. The most important aspects examined are: - determination of the amounts of TransUranium isotopes (TRU) generated in the reactor; - determination of the amounts of TRU which can be eliminated at every transmutation step, i.e. at every cycle; - determination of the factors which have most influence on the efficiency of the transmutation process; - evaluation of the consequences of the TRU recycling for the reactor design parameters

  8. Study of μs isomers in neutron-rich indium and cadmium isotopes

    International Nuclear Information System (INIS)

    Microsecond isomers in In and Cd isotopes, in the mass range A=123 to 130, were investigated at the ILL reactor, Grenoble, through thermal-neutron induced fission reactions of Pu targets. The LOHENGRIN mass spectrometer has been used to select the recoiling fission fragments. The level schemes of the odd-even 123,125,127,129In and 125Cd, and new measurements of the microsecond half-lives of the odd-odd 126-130In are reported. However, the expected 8+ isomers in the even-even 126,128,130Cd isotopes were not observed. The comparisons between the experimental B(M2) strengths for In and Sn isotopes are discussed. A shell-model study of the heaviest In and Cd nuclei was performed using a realistic interaction derived from the CD-Bonn nucleon-nucleon potential. The calculation predicts values of the half-lives of the first 8+ states in 126,128Cd of about 10 ns, which could explain the non-observation of microsecond isomers. Comparison shows that the calculated levels of 130In and 129In are in good agreement with the experimental values, while some discrepancies occur for the lighter In isotopes. The collectivity of 126,128Cd is discussed in the framework of the shell model and in comparison with 204Hg. A theoretical prediction on 130Cd is reported

  9. Radiochemical neutron activation analysis of zinc for stable isotope tracer studies in human nutrition

    International Nuclear Information System (INIS)

    Stable isotopes are beginning to be used to study trace element nutrition in humans. As they do not expose subjects to radiation, they will be very useful for population groups that can not be studied with radioactive tracers (pregnant women and persons under the age of 18). The zinc stable isotope used in experiments was 70Zn whose abundance was increased from 0.62% to 66%. Blood, urine and feces samples were collected at various times after the administration of the tracer and the ratios of Zn-70/Zn-64 and Zn-70/Zn-68 were determined in the collected samples. Neutron Activation Analysis (NAA) was used to determine the Zn isotopes. As biological samples contain large quantites of Na, Cl, Br, K it was necessary to separate these in order to detect Zn isotopes. Pre and post-irradiation separations were done. Chelex-100 was used for former, Mn was precipitated as MnO2 and Cu was separated by dithizone extraction. The yields for pre and post-irradiation separations for 90 samples were 86+-16% and 70+-13% respectively. (author)

  10. Gamow-Teller strength distributions for neutron-rich nitrogen, oxygen and fluorine isotopes

    Science.gov (United States)

    Zhang, Yu-Mei

    2016-08-01

    Gamow-Teller transition properties for neutron-rich nitrogen, oxygen and fluorine isotopes are studied in integrated energy. The structures of these nuclei are described by means of nuclear shell model with the WBT interaction in the p-sd shell space. Calculations of the Gamow-Teller strength distribution reproduce the experimental data reasonably in the low-energy region. For the dripline nucleus 24O, a super Gamow-Teller transition to a single state at excitation energy of 14.72 MeV in 24F is predicted. β-decay half-lives for these nuclei are calculated and compared with the available experimental data.

  11. Study of microsecond isomers in neutron-rich indium and cadmium isotopes

    OpenAIRE

    Scherillo, Antonella

    2005-01-01

    Microsecond isomers in In and Cd isotopes, in the mass range A = 123 to 130, were investigated at the ILL reactor, Grenoble, through thermal-neutron induced fission reactions of Pu targets. The LOHENGRIN mass spectrometer has been used to select the recoiling fission fragments. The level schemes of the odd-even 123,125,127,129In and 125Cd, and new measurements of the microsecond half-lives of the odd-odd 126-130In are reported. However, the expected 8+ isomers in the even-even 126,128,130$Cd ...

  12. Configuration mixing in the neutron-deficient $^{186-196}$Pb isotopes

    CERN Document Server

    Hellemans, V; Heyde, K

    2008-01-01

    In this article we report the results of detailed interacting boson model calculations with configuration mixing for the neutron-deficient Pb isotopes. Calculated energy levels and $B(E2)$ values for $^{188-196}$Pb are discussed and some care is suggested concerning the current classification on the basis of level systematics of the $4_1^+$ and $6_1^+$ states in $^{190-194}$Pb. Furthermore, quadrupole deformations are extracted for $^{186-196}$Pb and the mixing between the different families (0p-0h, 2p-2h, and 4p-4h) is discussed in detail. Finally, the experimental and the theoretical level systematics are compared.

  13. Investigation of the mechanism of fast neutron scattering by even isotopes of molybdenum

    International Nuclear Information System (INIS)

    Experimental differential and integral cross-sections of elastic and inelastic scattering of neutrons by the isotopes 92Mo and 94Mo are given. The experimental data are analysed in the framework of the spherical optical model, of the coupled-channel method and also of up-to-date versions of the statistical theory of nuclear reactions. A theoretical analysis is used to determine the ratio of the contributions of the two scattering mechanisms, namely direct scattering and scattering through a compound nucleus. (author)

  14. Beta-delayed particle emission from neutron-deficient tellurium, iodine, xenon, cesium and barium isotopes

    International Nuclear Information System (INIS)

    Using 58Ni, 63Cu(58Ni, xp yn) reactions and on-line mass separation the β-delayed proton and α-particle emission from neutron-deficient isotopes with 52113Xe, (protons), 114Cs (protons and α-particles) and 117Ba (protons). Coincidences between positons and β-delayed protons were recorded for 113Xe and 114Cs, yielding Qsub(EC)-Ssub(p) values of 7.92(15) and 8.73(15) MeV, respectively. The results are discussed within the statistical model. (orig.)

  15. Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes

    CERN Multimedia

    We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.

  16. Application of the generator coordinate method to neutron-rich Se and Ge isotopes

    Directory of Open Access Journals (Sweden)

    Higashiyama Koji

    2014-03-01

    Full Text Available The quantum-number projected generator coordinate method (GCM is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions.

  17. Further studies of neutron-deficient Sn-isotopes using REX-ISOLDE

    CERN Multimedia

    Larsen, A; Syed naeemul, H; Siem, S

    2007-01-01

    Encouraged by the committee to submit the latter part of our latest addendum to experiment IS418 under a new heading this proposal focuses on the second physics case mentioned there. We propose to use Coulomb excitation of odd mass neutron-deficient Sn isotopes to study some dominantly "one quasi-particle" states in these nuclei. Due to spin selection rules these states are difficult to populate following either $\\beta$-decay or in a cascade after a fusion-evaporation reactions, whereas the excitation from the ground-state is of E2 character for some of the most interesting cases.

  18. The thermal neutron capture cross section of the radioactive isotope $^{60}$Fe

    CERN Document Server

    Heftrich, T; Dressler, R; Eberhardt, K; Endres, A; Glorius, J; Göbel, K; Hampel, G; Heftrich, M; Käppeler, F; Lederer, C; Mikorski, M; Plag, R; Reifarth, R; Stieghorst, C; Schmidt, S; Schumann, D; Slavkovská, Z; Sonnabend, K; Wallner, A; Weigand, M; Wiehl, N; Zauner, S

    2015-01-01

    50% of the heavy element abundances are produced via slow neutron capture reactions in different stellar scenarios. The underlying nucleosynthesis models need the input of neutron capture cross sections. One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive isotopes, such as $^{60}$Fe with a half-life of $2.60\\times10^6$ yr. To reproduce this $\\gamma$-activity in the universe, the nucleosynthesis of $^{60}$Fe has to be understood reliably. A $^{60}$Fe sample produced at the Paul-Scherrer-Institut was activated with thermal and epithermal neutrons at the research reactor at the Johannes Gutenberg-Universit\\"at Mainz. The thermal neutron capture cross section has been measured for the first time to $\\sigma_{\\text{th}}=0.226 \\ (^{+0.044}_{-0.049})$ b. An upper limit of $\\sigma_{\\text{RI}} < 0.50$ b could be determined for the resonance integral. An extrapolation towards the astrophysicaly interesting energy regime between $kT$=10 keV and 100 ke...

  19. β-decay studies of the neutron-rich 18,21N isotopes

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The β-decay studies of neutron-rich 18,21N isotopes have been performed using β-n, β-γ, and β-n-γ coincidence methods. The 18,21N ions were produced by the fragmentation of the 22Ne and 26Mg beams, respectively, on a thick beryllium target. The time of flight of the emitted neutrons following the β-decay of 18,21N was measured by a neutron detector system with wide energy detection range and low-energy detection threshold. In addition, several clover germanium detectors were used to detect the β-delayed γ-rays. The half-lives of the β-decays of 18N and 21N were determined to be (619±2) ms and (82.9±7.5) ms, respec tively. Several new β-delayed neutron groups were observed with a total branching ratio of (6.98±1.46)% and (90.5±4.2)% for 18N and 21N, respectively. The level schemes of 18O and 21O were deduced. The experimental Gamow-Teller β-decay strengths of 18N and 21N to these levels were compared with the shell model calculations.

  20. Neutron capture cross-section studies of Tellurium isotopes for neutrinoless double beta decay applications

    Science.gov (United States)

    Bhike, Megha; Tornow, Werner

    2014-09-01

    The CUORE detector at Gran Sasso, aimed at searching for neutrinoless double-beta decay of 130Te, employs an array of TeO2 bolometer modules. To understand and identify the contribution of muon and (α,n) induced neutrons to the CUORE background, fast neutron cature cross-section data of the tellurium isotopes 126Te, 128Te and 130Te have been measured with the activation method at eight different energies in the neutron energy range 0.5-7.5 MeV. Plastic pill boxes of diameter 1.6 cm and width 1 cm containing Te were irradiated with mono-energetic neutrons produced via the 3H(p,n)3He and 2H(d,n)3He reactions. The cross-sections were determined relative to the 197Au(n, γ)198Au and 115In(n,n')115m In standard cross sections. The activities of the products were measured using 60% lead-shielded HPGe detectors at TUNL's low background counting facility. The present results are compared with the evaluated data from TENDL-2012, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0, as well as with literature data.

  1. MCNPX characterization of the secondary neutron flux at the Los Alamos Isotope Production Facility

    Energy Technology Data Exchange (ETDEWEB)

    Engle, Jonathan W., E-mail: jwengle@lanl.gov; James, Michael R.; Mashnik, Stepan G.; Kelsey, Charles T.; Wolfsberg, Laura E.; Reass, David A.; Connors, Michael A.; Bach, Hong T.; Fassbender, Michael E.; John, Kevin D.; Birnbaum, Eva R.; Nortier, Francois M.

    2014-08-01

    The spallation neutron flux produced from proton irradiation of rubidium chloride and gallium targets at the Los Alamos National Laboratory (LANL) Isotope Production Facility (IPF) was investigated using the activation foil technique and computational simulation. Routine irradiations have been found to produce fluxes as high as 10{sup 12} n cm{sup −2} s{sup −1}, with approximately 50% of the total flux having energy in excess of 1 MeV. Measurements of activation foils are compared with the predicted radionuclide yield using nuclear excitation functions from MCNPX event generators, evaluated nuclear data, and the TALYS nuclear code. Practical application of the secondary neutron flux in the realm of radioisotope production is considered. - Highlights: • MCNPX event generator simulations describe secondary neutron flux at the Los Alamos IPF. • Medium-energy monitor reactions using metal foils experimentally validate MCNPX predictions. • MCNPX is used to examine CEM03.02, Bertini, and TALYS reaction models of medium energy neutron-induced reactions.

  2. Neutron induced reaction for long-lived isotopes produced in fusion materials

    International Nuclear Information System (INIS)

    In present work the focus is to study the interaction of neutrons with long-lived isotopes (A=50-60) using nuclear reaction modular codes. There is no experimental data of neutron induced reactions for such radionuclides, because of the non-availability of these materials in nature. In this case the only way to generate such data is by the use of theoretical model codes. Recent advancement in this field with new codes such as TALYS and EMPIRE it is imperative that if optimized model parameters (along with proper validation of the code) are used then sufficiently accurate data could be obtained for many of the reactions. The neutron induced reactions cross-sections have been calculated for the long-lived radioisotopes and compared with the available discrepant values in the data libraries. Recently the surrogate technique has been used to measure the 55Fe(n,p) reaction in the neutron energy range of 8-20 MeV

  3. EVALUATION OF NEUTRON CROSS SECTIONS FOR A COMPLETE SET OF Nd ISOTOPES.

    Energy Technology Data Exchange (ETDEWEB)

    KIM,H.; HERMAN, M.; MUGHABGHAB, S.F.; OBLOZINSKY, P.; ROCHMAN, D.; LEE. Y.-O.

    2007-10-29

    Neutron cross sections for a complete set of Nd isotopes, {sup 142,143,144,145,146,147,148,150}Nd, were evaluated in the incident energy range from 10{sup -5} eV to 20 MeV. In the low energy region, including thermal and resolved resonances, our evaluations are based on the latest data published in the Atlas of Neutron Resonances. In the unresolved resonance region we performed additional evaluation by using the averages of the resolved resonances and adjusting them to the experimental data. In the fast neutron region, we used the nuclear reaction model code EMPIRE-2.19 validated against the experimental data. The results are compared to the existing nuclear data libraries, including ENDF/B-VI.8, JENDL-3.3 and JEFF-3.1, and to the available experimental data. The new evaluations are suitable for neutron transport calculations and they were adopted by the new evaluated nuclear data file of the United States, ENDF/B-VII.0, released in December 2006.

  4. FiR 1 reactor in service for boron neutron capture therapy (BNCT) and isotope production

    International Nuclear Information System (INIS)

    The FiR 1 reactor, a 250 kW Triga reactor, has been in operation since 1962. The main purpose for the existence of the reactor is now the Boron Neutron Capture Therapy (BNCT), but FiR 1 has also an important national role in providing local enterprises and research institutions in the fields of industrial measurements, pharmaceuticals, electronics etc. with isotope production and activation analysis services. In the 1990's a BNCT treatment facility was built at the FiR 1 reactor located at Technical Research Centre of Finland. A special new neutron moderator material FluentalTM (Al+AlF3+Li) developed at VTT ensures the superior quality of the neutron beam. Also the treatment environment is of world top quality after a major renovation of the whole reactor building in 1997. Recently the lithiated polyethylene neutron shielding of the beam aperture was modified to ease the positioning of the patient close to the beam aperture. Increasing the reactor power to 500 kW would allow positioning of the patient further away from the beam aperture. Possibilities to accomplish a safety analysis for this is currently under considerations. Over thirty patients have been treated at FiR 1 since May 1999, when the license for patient treatment was granted to the responsible BNCT treatment organization, Boneca Corporation. Currently three clinical trial protocols for tumours in the brain as well as in the head and neck region are recruiting patients. (author)

  5. Coulomb breakup of neutron-rich $^{29,30}$Na isotopes near the island of inversion

    CERN Document Server

    Rahaman, A; Aumann, T; Beceiro-Novo, S; Boretzky, K; Caesar, C; Carlson, B V; Catford, W N; Chakraborty, S; Chartier, M; Cortina-Gil, D; Angelis, G De; Gonzalez-Diaz, D; Emling, H; Fernandez, P Diaz; Fraile, L M; Ershova, O; Geissel, H; Jonson, B; Johansson, H; Kalantar-Nayestanaki, N; Krücken, R; Kröll, T; Kurcewicz, J; Langer, C; Bleis, T Le; Leifels, Y; Münzenberg, G; Marganiec, J; Nilsson, T; Nociforo, C; Nowacki, F; Najafi, A; Panin, V; Paschalis, S; Plag, R; Poves, A; Ray, I; Reifarth, R; Rigollet, C; Ricciardi, V; Rossi, D; Scheit, H; Simon, H; Scheidenberger, C; Typel, S; Taylor, J; Togano, Y; Volkov, V; Weick, H; Wagner, A; Wamers, F; Weigand, M; Winfield, J S; Yakorev, D; Zoric, M

    2016-01-01

    First results are reported on the ground state configurations of the neutron-rich $^{29,30}$Na isotopes, obtained via Coulomb dissociation (CD) measurements as a method of the direct probe. The invariant mass spectra of those nuclei have been obtained through measurement of the four-momentum of all decay products after Coulomb excitation on a $^{208}Pb$ target at energies of 400-430 MeV/nucleon using FRS-ALADIN-LAND setup at GSI, Darmstadt. Integrated Coulomb-dissociation cross-sections (CD) of 89 $(7)$ mb and 167 $(13)$ mb up to excitation energy of 10 MeV for one neutron removal from $^{29}$Na and $^{30}$Na respectively, have been extracted. The major part of one neutron removal, CD cross-sections of those nuclei populate core, in its' ground state. A comparison with the direct breakup model, suggests the predominant occupation of the valence neutron in the ground state of $^{29}$Na${(3/2^+)}$ and $^{30}$Na${(2^+)}$ is the $d$ orbital with small contribution in the $s$-orbital which are coupled with ground ...

  6. Awareness, Preference, Utilization, and Messaging Research for the Spallation Neutron Source and High Flux Isotope Reactor

    International Nuclear Information System (INIS)

    Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world, and the SNS is one of the world's most intense pulsed neutron beams. Management of these two resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD commissioned this survey research to develop baseline information regarding awareness of and perceptions about neutron science. Specific areas of investigative interest include the following: (1) awareness levels among those in the scientific community about the two neutron sources that ORNL offers; (2) the level of understanding members of various scientific communities have regarding benefits that neutron scattering techniques offer; and (3) any perceptions that negatively impact utilization of the facilities. NScD leadership identified users of two light sources in North America - the Advanced Photon Source (APS) at Argonne National Laboratory and the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory - as key publics. Given the type of research in which these scientists engage, they would quite likely benefit from including the neutron techniques available at SNS and HFIR among their scientific investigation tools. The objective of the survey of users of APS, NSLS, SNS, and HFIR was to explore awareness of and perceptions regarding SNS and HFIR among those in selected scientific communities. Perceptions of SNS and FHIR will provide a foundation for strategic communication plan development and for developing key educational messages. The survey was conducted in two phases. The first phase included qualitative methods of (1) key stakeholder meetings; (2) online interviews with user administrators of APS and NSLS; and (3) one-on-one interviews

  7. Awareness, Preference, Utilization, and Messaging Research for the Spallation Neutron Source and High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Rebecca [Bryant Research, LLC; Kszos, Lynn A [ORNL

    2011-03-01

    Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world, and the SNS is one of the world's most intense pulsed neutron beams. Management of these two resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD commissioned this survey research to develop baseline information regarding awareness of and perceptions about neutron science. Specific areas of investigative interest include the following: (1) awareness levels among those in the scientific community about the two neutron sources that ORNL offers; (2) the level of understanding members of various scientific communities have regarding benefits that neutron scattering techniques offer; and (3) any perceptions that negatively impact utilization of the facilities. NScD leadership identified users of two light sources in North America - the Advanced Photon Source (APS) at Argonne National Laboratory and the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory - as key publics. Given the type of research in which these scientists engage, they would quite likely benefit from including the neutron techniques available at SNS and HFIR among their scientific investigation tools. The objective of the survey of users of APS, NSLS, SNS, and HFIR was to explore awareness of and perceptions regarding SNS and HFIR among those in selected scientific communities. Perceptions of SNS and FHIR will provide a foundation for strategic communication plan development and for developing key educational messages. The survey was conducted in two phases. The first phase included qualitative methods of (1) key stakeholder meetings; (2) online interviews with user administrators of APS and NSLS; and (3) one

  8. On the effect of the moderator dimensions and energy spectrum of neutrons from isotope sources on the slow neutron flux density distribution in water

    International Nuclear Information System (INIS)

    Results are given of experimental investigations on the effect of moderator dimensions and neutron energy spectra of 238Pu+Be, 238Pu+B, 238Pu+Li+F, 252Cf isotope sources on the distribution of the slow neutron flux density in water moderator. The analysis of obtained results shows that the neutron flux density approximating the maximum possible one is attained in water at dimensions of the cylindrical moderator of the order of 40x40 cm. By comparing the obtained data with the results of calculations a conclusion has been drawn that calculated estimates are 2.5-3 times lower than experimental ones

  9. Gamma and neutron attenuation properties of barite-cement mixture

    Science.gov (United States)

    Picha, R.; Channuie, J.; Khaweerat, S.; Liamsuwan, T.; Promping, J.; Ratanatongchai, W.; Silva, K.; Wonglee, S.

    2015-05-01

    For the neutron radiography facility renovation plan at Thai Research Reactor, mixed barite-concrete blocks of different compositions were tested for their photon and neutron radiation attenuation properties. 60Co and 137Cs isotopes were used as the gamma sources; 241Am-Be was used as the neutron source. For detection, a scintillation counter and a BF3 tube were used. The intensities at various energies were measured and attenuation coefficients were calculated. Samples of barite mixture were analyzed with X-ray. The results involving the effects of barite are reported and discussed.

  10. Charge radii and nuclear moments of neutron-deficient potassium isotopes

    Science.gov (United States)

    Minamisono, K.; Barquest, B. R.; Bollen, G.; Hughes, M.; Strum, R.; Tarazona, D.; Asberry, H. B.; Cooper, K.; Hammerton, K.; Klose, A.; Mantica, P. F.; Morrissey, D. J.; Geppert, Ch.; Harris, J.; Ringle, R.; Rodriguez, J. A.; Rossi, D. M.; Ryder, C. A.; Smith, A.; Schwarz, S.; Sumithrarachchi, C.

    2014-09-01

    The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. This work was supported in part by NSF Grant No. PHY-11-02511.

  11. In-beam spectroscopy of very neutron deficient polonium isotopes 190,191Po

    International Nuclear Information System (INIS)

    The phenomenon of shape coexistence is experimentally well established in even-even light Pb, Hg and Pt nuclei. The light Po isotopes are predicted to exhibit similar features. Due to the experimental difficulties when approaching the proton drip-line, the lightest Po isotope for which in-beam γ-ray data exists prior this work has been 192Po. Since shape coexistence should be most pronounced at the neutron mid-shell (N=104), information about the excited states in lighter Po isotopes would be valuable in verifying the existence and possibly understanding the origin of the phenomenon in these nuclei. In the present work the recoil decay tagging method has been used to study excited states in the neutron deficient isotopes 190,191Po. Prompt γ-rays were detected with the Jurosphere Ge detector array coupled to the gas- filled separator RITU. The 191Po nuclei were produced in the 142Nd(52Cr,3n)191Po reaction at a bombarding energy of 240MeV. The observed prompt γ-rays correlated with the α-decay of the 191mPo 13/2+ state were placed in two cascades. Similar sequences have been observed in 193,195Po and presumably correspond to favoured and unfavoured states in the vi13 band. The unfavoured states are lowered below the favoured ones, resulting in a strongly coupled scheme which suggests oblate deformation. In a separate experiment the 142Nd(52Cr,4n)190Po reaction was used at higher beam energy. The production cross-section was approximately 200nb. Four prompt α-transitions correlated with the 190Po α-decay were observed and intepreted to form a cascade of E2 transitions up to spin 8+. In comparison to the heavier even Po isotopes, a drop in 6+ and 8+ energies is observed. This suggest an onset of prolate deformation in light Po isotopes as predicted by Oros et al. The results will be discussed in the framework of intruder states (author)

  12. Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures

    CERN Multimedia

    Blaum, K; Stroke, H H; Krieger, A R

    We propose to study the isotopic chain of cadmium with high-resolution laser spectroscopy for the first time. Our goal is to determine nuclear spins, moments and root-mean-square charge radii of ground and isomeric states between the neutron 50 and 82 shell closures, contributing decisively to a better understanding of the nuclear structure in the vicinity of the doubly-magic $^{100}$Sn and $^{132}$Sn. On the neutron-rich side this is expected to shed light on a shell-quenching hypothesis and consequently on the duration of the r-process along the waiting-point nuclei below $^{130}$Cd. On the neutron-deficient side it may elucidate the role of the cadmium isotopes in the rp-process for rapidly accreting neutron stars.

  13. Neutron Interactions as Seen by A Segmented Germanium Detector

    CERN Document Server

    Abt, I; Kroeninger, K; Liu, J; Liu, X; Majorovits, B

    2007-01-01

    The GERmanium Detector Array, GERDA, is designed for the search for ``neutrinoless double beta decay'' (0-nu-2-beta) with germanium detectors enriched in Ge76. An 18-fold segmented prototype detector for GERDA Phase II was exposed to an AmBe neutron source to improve the understanding of neutron induced backgrounds. Neutron interactions with the germanium isotopes themselves and in the surrounding materials were studied. Segment information is used to identify neutron induced peaks in the recorded energy spectra. The Geant4 based simulation package MaGe is used to simulate the experiment. Though many photon peaks from germanium isotopes excited by neutrons are correctly described by Geant4, some physics processes were identified as being incorrectly treated or even missing.

  14. Total neutron cross-sections for rare isotopes using a digital-signal-processing technique: Case study {sup 48}Ca

    Energy Technology Data Exchange (ETDEWEB)

    Shane, R. [Department of Physics, Washington University, Campus Box 1134, St. Louis, MO 63130 (United States); Charity, R.J.; Elson, J.M. [Department of Chemistry, Washington University, Campus Box 1134, St. Louis, MO 63130 (United States); Sobotka, L.G., E-mail: lgs@wustl.ed [Department of Physics, Washington University, Campus Box 1134, St. Louis, MO 63130 (United States); Department of Chemistry, Washington University, Campus Box 1134, St. Louis, MO 63130 (United States); Devlin, M.; Fotiades, N.; O' Donnell, J.M. [LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-03-11

    A digital-signal-processing method was developed and used to measure the total neutron cross-sections of {sup 48}Ca from 15 to 300 MeV. This technique allows for cross-sections to be obtained with high statistical accuracy even for samples that are an order of magnitude smaller than those used with conventional (non-digital) techniques. The isotopic and energy dependence of rare-isotope total neutron cross-sections are of considerable value for extracting the n/p asymmetry dependence of optical-model potentials.

  15. Slow neutron reactions in inverse kinematics for isotope production: a primer

    International Nuclear Information System (INIS)

    It appears possible that slow-neutron reactions can be induced in inverse kinematics when a beam of reactant-nuclei of right kinetic energy pass through a column of thermal-neutrons, however no experimental attempts in this direction have been reported. In attempting the inverse kinematics reactions, an obvious disadvantage is the low reactant density in a beam of particles; however, the situation is changing for the better. Advances taking place presently in ion, plasma, and neutral beam technologies would allow hyper-velocity ion and atom flow in a controlled manner (our interest is in few tens of km/s range) and particle densities in such beams are rapidly increasing. It is also pointed out that inverse reaction of above type is uniquely positioned to take advantage of the very high reaction cross-sections available at certain discrete-resonances, and of a possibility for online separation of transmuted-isotopes, the latter facilitated by use of reactants in form of hyper-velocity beams. It is therefore worthwhile to investigate if the reaction rates realizable by this method is suitable to produce radioactive tracer isotopes

  16. Study of shape transition in the neutron-rich Os isotopes

    Directory of Open Access Journals (Sweden)

    John P.R.

    2014-03-01

    Full Text Available The neutron-rich isotopes of tungsten, osmium and platinum have different shapes in their ground states and present also shape transitions phenomena. Spectroscopic information for these nuclei is scarce and often limited to the gamma rays from the decay of isomeric states. For the neutron-rich even-even osmium isotopes 194Os and 198Os, a shape transition between a slightly prolate deformed to an oblate deformed ground state was deduced from the observed level schemes. For the even-even nucleus lying in between, 196Os, no gamma ray transition is known. In order to elucidate the shape transition and to test the nuclear models describing it, this region was investigated through gamma-ray spectroscopy using the AGATA demonstrator and the large acceptance heavy-ion spectrometer PRISMA at LNL, Italy. A two-nucleon transfer from a 198Pt target to a stable 82Se beam was utilized to populate medium-high spin states of 196Os. The analysis method and preliminary results, including the first life-time measurement of isomeric states with AGATA, are presented.

  17. Neutron interactions with germanium isotopes and amorphous and crystalline GeO2

    Science.gov (United States)

    Koester, L.; Knopf, K.; Waschkowski, W.

    1987-06-01

    Coherent neutron scattering lengths and total cross sections have been measured on elemental and oxide samples of ordinary Ge and of isotopically enriched substances. From the experimental results the following values were obtained: the coherent scattering lengths (in fm) of the bound atoms Ge(8.185±0.020);70Ge(10.0±0.1);72Ge(8.51±0.10);73Ge(5.02±0.04);74Ge(7.58±0.10) and76Ge(8.2 ±1.5); the absorption cross sections at 0.0253 eV (in barn) for Ge(2.20±0.04);70Ge(2.9±0.2);72Ge(0.8±0.2);73Ge(14.4±0.4) and74Ge(0.4±0.2); the free cross sections for epithermal neutrons and the zero energy scattering cross sections. On the basis of this data, the isotopic- and spin-incoherent cross sections and the s-wave resonance contributions to the coherent scattering lengths have been determined and discussed. Transmission measurements at 0.57 meV on amorphous and crystalline GeO2 yielded for the amorphous sample an inelastic cross section eight times larger than for the crystalline samples. This effect corresponds to a clearly higher density of low energy states in the amorphous than in the crystalline substances.

  18. Neutron interactions with germanium isotopes and amorphous and crystalline GeO2

    International Nuclear Information System (INIS)

    Coherent neutron scattering lengths and total cross sections have been measured on elemental and oxide samples of ordinary Ge and of isotopically enriched substances. From the experimental results the following values were obtained: - the coherent scattering lengths (in fm) of the bound atoms Ge(8.185±0.020); 70Ge(10.0±0.1); 72Ge(8.51±0.10); 73Ge(5.02±0.04); 74Ge(7.58±0.10) and 76Ge(8.2±1.5); - the absorption cross section at 0.0253 eV (in barn) for Ge(2.20±0.04); 70Ge(2.9±0.2); 72Ge(0.8±0.2); 73Ge(14.4±0.4) and 74Ge(0.4±0.2); - the free cross sections for epithermal neutrons and the zero energy scattering cross sections. On the basis of this data, the isotopic- and spin-incoherent cross sections and the s-wave resonance contributions to the coherent scattering lengths have been determined and discussed. Transmission measurements at 0.57 meV on amorphous and crystalline GeO2 yielded for the amorphous sample an inelastic cross section eight times larger than for the crystalline samples. This effect corresponds to a clarly higher density of low energy states in the amorphous than in the crystalline substances. (orig.)

  19. First results on in-beam γ spectroscopy of neutron-rich Na and Mg isotopes at REX-ISOLDE

    International Nuclear Information System (INIS)

    After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium γ spectrometer MINIBALL

  20. The comparison of four neutron sources for Prompt Gamma Neutron Activation Analysis (PGNAA) in vivo detections of boron

    International Nuclear Information System (INIS)

    A Prompt Gamma Ray Neutron Activation Analysis (PGNAA) system, incorporating an isotopic neutron source has been simulated using the MCNPX Monte Carlo code. In order to improve the signal to noise ratio different collimators and a filter were placed between the neutron source and the object. The effect of the positioning of the neutron beam and the detector relative to the object has been studied. In this work the optimisation procedure is demonstrated for boron. Monte Carlo calculations were carried out to compare the performance of the proposed PGNAA system using four different neutron sources (241Am/Be, 252Cf, 241Am/B, and DT neutron generator). Among the different systems the 252Cf neutron based PGNAA system has the best performance. (author)

  1. Towards 100Sn: Studies on neutron-deficient even isotopes of tin

    International Nuclear Information System (INIS)

    Neutron-deficient 108,106,104Sn isotopes were produced by heavy ion induced fusion reactions using high-intensity 59Ni beams from the UNILAC of the GSI. Their decay properties were studied by techniques of gamma and conversion electron spectroscopy employing the mass separator on-line to the UNILAC. Earlier information on the 108Sn → 108In and 106Sn → 106In decays was complemented and improved in the course of this work. The new nucleus 104Sn and its decay to excited states in 104In was identified and studied for the first time. These investigations yield the following results: the mass of 104Sn and of nuclei linked to it by alpha decay or proton radioactivity, 108Te, 112Xe and 109I, 113Cs, respectively were determined from the measured QEC value of 104Sn and the known mass value of 104In. These are nuclei very close or beyond the proton drip line. In addition, information on the quenching of the fast Gamow-Teller beta decay of the even neutron-deficient tin isotopes was obtained. This complements investigations on the N = 50 isotones 94Ru and 96Pd, and allows a systematic comparison of these transition strengths for nuclei near the doubly magic 100Sn. The spreading of the vertical strokeπg9/2-1 vg 7/2, 1+ > configuration over several states, due to residual interactions, and the centroid energies of these magnetic dipole states were determined for the corresponding odd-odd indium isotopes. (orig./HSI)

  2. Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation

    CERN Multimedia

    Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O

    We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.

  3. Astrophysical Implication of Low E(2^+_1) in Neutron-rich Sn Isotopes

    CERN Document Server

    Sarkar, S

    2009-01-01

    The observation and prediction of unusually depressed first excited 2^+_1 states in even-A neutron - rich isotopes of semi-magic Sn above 132Sn provide motivations for reviewing the problems related to the nuclear astrophysics in general. In the present work, the beta-decay rates of the exotic even Sn isotopes (134,136Sn) above the 132Sn core have been calculated as a function of temperature (T). In order to get the necessary ft values, B(GT) values corresponding to allowed Gamow Teller (GT-) beta-decay have been theoretically calculated using shell model. The total decay rate shows decrease with increasing temperature as the ground state population is depleted and population of excited states with slower decay rates increases. The abundance at each Z value is inversely proportional to the decay constant of the waiting point nucleus for that particular Z. So the increase in half-life of isotopes of Sn, like 136Sn, might have substantial impact on the r-process nucleosynthesis.

  4. The capture cross sections of the neon isotopes and the s-process neutron balance

    International Nuclear Information System (INIS)

    The neutron capture cross sections of the three stable neon isotopes have been measured by the time-of-flight method in the energy range from 5 to 200 keV, using hydrogen free fast liquid scintillator detectors and the Maier-Leibnitz pulse height weighting technique. As a result it was found that neutron absorption by the light elements, from 20Ne to 56Fe, is dominated not by 22Ne but by 25Mg. The condition that as many neutrons should be produced as are absorbed has led to the conclusion that at least 80% of the 22Ne must undergo the (α,n) reaction, which implies that less than 20% can undergo the (α,γ) reaction. Therefore the (α,n) reaction rate must be at least 4 times faster than the (α,γ) rate. An inspection of these reaction rates as a function of temperature shows that this condition can be satisfied only for T > 3.2 108 K, or kT > 28 keV. (orig./HSI)

  5. A neutron booster for spallation sources--application to accelerator driven systems and isotope production

    CERN Document Server

    Galy, J; Van Dam, H; Valko, J

    2002-01-01

    One can design a critical system with fissile material in the form of a thin layer on the inner surface of a cylindrical neutron moderator such as graphite or beryllium. Recently, we have investigated the properties of critical and near critical systems based on the use of thin actinide layers of uranium, plutonium and americium. The thickness of the required fissile layer depends on the type of fissile material, its concentration in the layer and on the geometrical arrangement, but is typically in the mu m-mm range. The resulting total mass of fissile material can be as low as 100 g. Thin fissile layers have a variety of applications in nuclear technology--for example in the design neutron amplifiers for medical applications and 'fast' islands in thermal reactors for waste incineration. In the present paper, we investigate the properties of a neutron booster unit for spallation sources and isotope production. In those applications a layer of fissile material surrounds the spallation source. Such a module cou...

  6. Single-neutron orbits near 78Ni: Spectroscopy of the N=49 isotope 79Zn

    Directory of Open Access Journals (Sweden)

    R. Orlandi

    2015-01-01

    Full Text Available Single-neutron states in the Z=30, N=49 isotope 79Zn have been populated using the 78Zn(d, p79Zn transfer reaction at REX-ISOLDE, CERN. The experimental setup allowed the combined detection of protons ejected in the reaction, and of γ rays emitted by 79Zn. The analysis reveals that the lowest excited states populated in the reaction lie at approximately 1 MeV of excitation, and involve neutron orbits above the N=50 shell gap. From the analysis of γ-ray data and of proton angular distributions, characteristic of the amount of angular momentum transferred, a 5/2+ configuration was assigned to a state at 983 keV. Comparison with large-scale-shell-model calculations supports a robust neutron N=50 shell-closure for 78Ni. These data constitute an important step towards the understanding of the magicity of 78Ni and of the structure of nuclei in the region.

  7. Single-neutron orbits near 78Ni: Spectroscopy of the N=49 isotope 79Zn

    International Nuclear Information System (INIS)

    Single-neutron states in the Z=30, N=49 isotope 79Zn have been populated using the 78Zn(d, p)79Zn transfer reaction at REX-ISOLDE, CERN. The experimental setup allowed the combined detection of protons ejected in the reaction, and of γ rays emitted by 79Zn. The analysis reveals that the lowest excited states populated in the reaction lie at approximately 1 MeV of excitation, and involve neutron orbits above the N=50 shell gap. From the analysis of γ-ray data and of proton angular distributions, characteristic of the amount of angular momentum transferred, a 5/2+ configuration was assigned to a state at 983 keV. Comparison with large-scale-shell-model calculations supports a robust neutron N=50 shell-closure for 78Ni. These data constitute an important step towards the understanding of the magicity of 78Ni and of the structure of nuclei in the region

  8. Direct mass measurements of neutron-rich 86Kr projectile fragments and the persistence of neutron magic number N=32 in Sc isotopes

    Science.gov (United States)

    Xu, Xing; Wang, Meng; Zhang, Yu-Hu; Xu, Hu-Shan; Shuai, Peng; Tu, Xiao-Lin; Yuri, A. Litvinov; Zhou, Xiao-Hong; Sun, Bao-Hua; Yuan, You-Jin; Xia, Jia-Wen; Yang, Jian-Cheng; Klaus, Blaum; Chen, Rui-Jiu; Chen, Xiang-Cheng; Fu, Chao-Yi; Ge, Zhuang; Hu, Zheng-Guo; Huang, Wen-Jia; Liu, Da-Wei; Lam, Yi-Hua; Ma, Xin-Wen; Mao, Rui-Shi; Uesaka, T.; Xiao, Guo-Qing; Xing, Yuan-Ming; Yamaguchi, T.; Yamaguchi, Y.; Zeng, Qi; Yan, Xin-Liang; Zhao, Hong-Wei; Zhao, Tie-Cheng; Zhang, Wei; Zhan, Wen-Long

    2015-10-01

    In this paper, we present direct mass measurements of neutron-rich 86Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of 52-54Sc nuclides are determined to be -40492(82), -38928(114), -34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, 53Sc and 54Sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number N=32 in Sc isotopes. Supported by 973 Program of China (2013CB834401), the NSFC (U1232208, U1432125, 11205205, 11035007) and the Helmholtz-CAS Joint Research Group (HCJRG-108)

  9. Direct mass measurements of neutron-rich $^{86}$Kr projectile fragments and the persistence of neutron magic number $N$ = 32 in Sc isotopes

    CERN Document Server

    Xu, Xing; Zhang, Yu-hu; Xu, Hu-shan; Shuai, Peng; Tu, Xiao-lin; Litvinov, Yuri A; Zhou, Xiao-hong; Sun, Bao-hua; Yuan, You-jin; Xia, Jia-wen; Yang, Jian-cheng; Blaum, KLaus; Chen, Rui-jiu; Chen, Xiang-cheng; Fu, Chao-yi; Ge, Zhuang; Hu, Zheng-guo; Huang, Wen-jia; Liu, Da-wei; Lam, Yi-hua; Ma, Xin-wen; Mao, Rui-shi; Uesaka, T; Xiao, Guo-ging; Xing, Yuan-ming; Yamaguchi, T; Yamaguchi, Y; Zeng, Qi; Yan, Xin-liang; Zhao, Hong-wei; Zhao, Tie-cheneg; Zhang, Wei; Zhan, Wen-long

    2016-01-01

    In this paper, we present direct mass measurements of neutron-rich $^{86}$Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of $^{52-54}$Sc nuclides are determined to be -40492(82), -38928(114), -34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, $^{53}$Sc and $^{54}$Sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number $N$ = 32 in Sc isotopes.

  10. High resolution neutron total and capture cross-sections in separated isotopes of copper (6365Cu)

    International Nuclear Information System (INIS)

    High resolution neutron total and capture cross section measurements have been performed on separated isotopes of copper (6365Cu). Measurements for capture cross section were made from about 1 keV to a few hundreds of keV. The total cross section measurements were made in the energy interval of approximately 10 keV to 150 keV. The resulting capture data have been analyzed by a generalized least square peak fitting computer code in the energy interval of 2.5 keV to 50 keV. Photon strengths are determined using the data up to approximately 250 keV. The resulting total cross section data have been analyzed by area-analysis on the transmission values and by R-matrix multilevel code on cross section values. Average s- and p-wave level spacing and s- and p-wave strength function values are determined. From the resonance parameters thus obtained, by the analysis, statistical distribution is studied for s- and p-wave level spacings and reduced neutron widths. A comparison has been made for adjacent level spacings with the theoretical predictions of level repulsion (of same J/sup π/) by Wigner considering levels with various spin states separately for s-wave resonances where confident spin assignment has been possible. Reduced neutron widths are compared with the Porter-Thomas distribution. Optical model formulated by Feshbach, Porter and Weiskopf describes the neutron-nucleus interaction. A comparison has been made between experimentally determined values of the s- and p-wave strength functions and that obtainable from optical model calculations, thereby determining the appropriate optical model parameters. The experimental arrangement, pertinent theoretical discussion, and the processes of data reduction and the analyses along with the comparison of the previously reported results with the present work are presented in detail

  11. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ch

    2000-09-15

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons.

  12. Beyond the neutron drip line: The unbound oxygen isotopes 25O and 26O

    DEFF Research Database (Denmark)

    Caesar, C.; Simonis, J.; Adachi, T.; Aksyutina, Y.; Alcantara, J.; Altstadt, S.; Alvarez-Pol, H.; Ashwood, N.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C.A.; Boretzky, K.; Borge, M.J.G.; Burgunder, G.; Caamano, M.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chakraborty, S.; Chartier, M.; Chulkov, L.; Cortina-Gil, D.; Datta Pramanik, U.; Diaz Fernandez, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estrade, A.; Farinon, F.; Fraile, L.M.; Freer, M.; Freudenberger, M.; Fynbo, H.O.U.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Gonzalez Diaz, D.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Holt, J.; Ickert, G.; Ignatov, A.; Jakobsson, B.; Johansson, H. T.; Jonson, B.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knöbel, R.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lepyoshkina, O.; Lindberg, S.; Machado, J.; Marganiec, J.; Maroussov, V.; Menéndez, J.; Mostazo, M.; Movsesyan, A.; Najafi, A.; Nilsson, T.; Nociforo, C.; Panin, V.; Perea, A.; Pietri, S.; Plag, R.; Prochazka, A.; Rahaman, A.; Rastrepina, G.; Reifarth, R.; Ribeiro, G.; Ricciardi, M.V.; Rigollet, C.; Riisager, K.; Röder, M.; Rossi, D.; Sanchez Del Rio, J.; Savran, D.; Scheit, H.; Schwenk, A.; Simon, H.; Sorlin, O.; Stoica, V.; Streicher, B.; Taylor, J.; Tengblad, O.; Terashima, S.; Thies, R.; Togano, Y.; Uberseder, E.; Van De Walle, J.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Wheldon, C.; Wilson, G.; Wimmer, C.; Winfield, J.S.; Woods, P.; Yakorev, D.; Zhukov, M.V.; Zilges, A.; Zoric, M.; Zuber, K.

    2013-01-01

    The very neutron-rich oxygen isotopes 25O and 26O are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from 26F and 27F at relativistic energies around 442 and 414 MeV/nucleon, res...

  13. Probing the collectivity in neutron-rich Cd isotopes via γ-ray spectroscopy

    International Nuclear Information System (INIS)

    The spin and configurational structure of excited states of 127Cd, 125Cd and 129Cd, having two proton and three, five and one neutron holes, respectively in the doubly magic 132Sn core have been studied. The isomeric states in Cd isotopes were populated in the fragmentation of a 136Xe beam at an energy of 750 MeV/u on a 9Be target of 4 g/cm2. The experiment was performed at GSI Darmstadt. The neutron-rich Cd isotopes were selected using the Bρ - ΔE - Bρ method at the FRagment Separator (FRS). Event by event identification of fragments in terms of their A (mass) and Z (charge) was provided by the standard FRS detectors. The reaction residues were implanted in a plastic stopper surrounded by 15 Ge cluster detectors from the RISING array to detect the γ decays. In 127Cd, an isomeric state with a half-life of 17.5(3) μs has been detected. This yrast (19/2)+ isomer is proposed to have mixed proton-neutron configurations and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129Sn. In 125Cd, apart from the previously observed (19/2)+ isomer, two new metastable states at 3896 keV and 2141 keV have been detected. A half-life of 13.6(2) μs was measured for the (19/2)+ isomer, having a decay structure similar to the corresponding isomeric state in 127Cd. The higher lying isomers have a half-life of 3.1(1) μs and 2.5(15) ns, respectively. Time distributions of delayed γ transitions and γγ-coincidence relations were exploited to construct decay schemes for the two nuclei. Comparison of the experimental data with shell-model calculations is also discussed. The new information provides input for the proton-neutron interaction in nuclei around the doubly magic 132Sn core. The γ decays of the isomeric states in 129Cd were not observed experimentally. The reasons for the non-observation of delayed γ rays for 129Cd are either an isomeric half-life of less than 93 ns based on the experimentally obtained isomeric

  14. FIR 1 reactor in service for boron neutron capture therapy (BNCT) and isotope production

    International Nuclear Information System (INIS)

    Full text: The FIR 1-reactor, a 250 kW Triga reactor, has been in operation since 1962. The main purpose for the existence of the reactor is now the Boron Neutron Capture Therapy (BNCT). The BNCT work dominates the current utilization of the reactor: three or four days per week are reserved for BNCT purposes and the rest for other purposes such as isotope production and neutron activation analysis. In the 1990's a BNCT treatment facility was build at the FiR1 reactor located at Technical Research Centre of Finland. A special new neutron moderator material FluentalTM (Al+AlF3+Li) developed at VTT ensures the superior quality of the neutron beam. Also the treatment environment is of world top quality. The ground floor of the reactor hall was provided with a new entrance, easily accessible by any patient vehicle, a radio therapy control room and rooms for patient preparation and laboratories. The top of the reactor tank was separated from the reactor hall in order to confine contamination in case of a leakage from irradiation samples or fuel elements. The ventilation of the building, emergency power supply system, heat exchangers and the secondary cooling circuit of the reactor including cooling towers were completely redesigned and rebuilt. The expenditure of designing and accomplishing the construction work described was about 4 million euros. The costs were partly financed with venture capital via Radtek Ltd., particularly established for this enterprise. Close to thirty patients have been treated at FiR 1 since May 1999, when the license for patient treatment was granted to the responsible BNCT treatment organization, Boneca Corporation. VTT as the reactor operator has a long term contract with the Boneca Corp. to provide the facility and irradiation services for the patient treatments. The BNCT facility has been licensed for clinical use and is being surveyed by several national public health authorities including the Finnish Nuclear and Radiation Safety

  15. Competing $\\gamma$-rigid and $\\gamma$-stable vibrations in neutron rich Gd and Dy isotopes

    CERN Document Server

    Budaca, R

    2015-01-01

    An exactly separable version of the Bohr Hamiltonian which combines the $\\gamma$-stable and $\\gamma$-rigid axial vibration-rotation is used to describe the collective properties of few neutron rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape-phase space. While the $\\gamma$-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff $\\gamma$ oscillation hypothesis, the $\\beta$ vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables.

  16. High-precision masses of neutron-deficient rubidium isotopes using a Penning trap mass spectrometer

    CERN Document Server

    Kellerbauer, A G; Beck, D; Blaum, K; Bollen, G; Guénaut, C; Herfurth, F; Herlert, A; Kluge, H J; Lunney, D; Schwarz, S; Schweikhard, L; Weber, C; Yazidjian, C

    2007-01-01

    The atomic masses of the neutron-deficient radioactive rubidium isotopes $^{74-77,79,80,83}$Rb have been measured with the Penning trap mass spectrometer ISOLTRAP. Using the time-of-flight cyclotron resonance technique, relative mass uncertainties ranging from $1.6 \\times 10^{-8}$ to $5.6 \\times 10^{-8}$ were achieved. In all cases, the mass precision was significantly improved as compared with the prior Atomic-Mass Evaluation; no significant deviations from the literature values were observed. The exotic nuclide $^{74}$Rb with a half-life of only 65 ms, is the shortest-lived nuclide on which a high-precision mass measurement in a Penning trap has been carried out. The significance of these measurements for a check of the conserved-vector-current hypothesis of the weak interaction and the unitarity of the Cabibbo-Kobayashi-Maskawa matrix is discussed.

  17. Application of the generator coordinate method to neutron-rich Se and Ge isotopes

    International Nuclear Information System (INIS)

    The quantum-number projected generator coordinate method (GCM) is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions. The GCM results for axial deformations are not satisfactory enough to reproduce the energy levels of the quasi-γ band. Taking account of triaxial deformations is essentially important to describe the quasi-γ band

  18. Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

    OpenAIRE

    Reimer, P.; Avrigeanu, V.; Chuvaev, S. V.; Filatenkov, A. A.; Glodarin, T.; de Koning, A; Plompen, A. J. M.; Qaim, S. M.; Smith, D. L.; Weigmann, H.

    2005-01-01

    A large number of new measurements with the activation technique were performed for (n,2n) and neutron-induced Delta Z=1,2 reaction cross sections on the stable molybdenum isotopes in the energy range from 13.5 to 21 MeV. First results were obtained for the Mo-92(n,2n)Mo-91(m),Mo-92(n,alpha)Zr-89(m),Mo-94(n,2n)Mo-93(m),Mo-95(n,p)Nb-95(m),Mo-96(n,p)Nb-96,Mo-96(n,x)Nb-95(m), Mo-97(n,p)Nb-97, Mo-97(n,p)Nb-97(m), Mo-97(n,x)Nb-96, Mo-98(n,p)Nb-98(m), Mo-98(n,x)Nb-97, Mo-98(n,x)Nb-97(m), and Mo-100...

  19. FiR 1 Reactor in Service for Boron Neutron Capture Therapy (BNCT) and Isotope Production

    International Nuclear Information System (INIS)

    The FiR 1 reactor, a 250 kW Triga reactor, has been in operation since 1962. The main purpose to run the reactor is now the Boron Neutron Capture Therapy (BNCT). Although BNCT dominates the current utilization of the reactor, it also has an important national role in providing local enterprises and research institutions in the fields of industrial measurements, pharmaceuticals, electronics, etc. with isotope produc- tion and activation analysis services. The whole reactor building has been renovated, creating a dedicated clinical BNCT facility at the reactor. Close to 30 patients have been treated since May 1999, when the licence for patient treatment was granted to the responsible BNCT treatment organization. The treatment organization has a close connection to the Helsinki University Central Hospital. (author)

  20. Electric dipole response of neutron-rich Calcium isotopes in relativistic quasiparticle time blocking approximation

    CERN Document Server

    Egorova, Irina A

    2016-01-01

    New results for electric dipole strength in the chain of even-even Calcium isotopes with the mass numbers A = 40 - 54 are presented. Starting from the covariant Lagrangian of Quantum Hadrodynamics, spectra of collective vibrations (phonons) and phonon-nucleon coupling vertices for $J \\leq 6$ and normal parity were computed in a self-consistent relativistic quasiparticle random phase approximation (RQRPA). These vibrations coupled to Bogoliubov two-quasiparticle configurations (2q$\\otimes$phonon) form the model space for the calculations of the dipole response function in the relativistic quasiparticle time blocking approximation (RQTBA). The results for giant dipole resonance in the latter approach are compared to those obtained in RQRPA and to available data. Evolution of the dipole strength with neutron number is investigated for both high-frequency giant dipole resonance (GDR) and low-lying strength. Development of a pygmy resonant structure on the low-energy shoulder of GDR is traced and analyzed in terms...

  1. Half-life measurement of heavy neutron-rich isotope 237Th

    International Nuclear Information System (INIS)

    The natural uranium targets are bombarded by 18O(60 MeV/u) ions, and the heavy neutron-rich isotope 237Th is produced through the multi-nucleon transfer reaction. A relatively fast radiochemical procedure is used to separate thorium from the uranium and complex reaction products mixture. The thorium fractions chemically separated are studied by off-line γ-ray spectroscopy using a HPGe detector coupled to a 4096 channel pulse-height analyzer. The growth-decay curve of 853.7 keV γ-ray from 237Pa (237Th daughter) are analyzed and the half-life of 237Th is determined to be 4.69 +- 0.60 min

  2. A neutron booster for spallation sources—application to accelerator driven systems and isotope production

    Science.gov (United States)

    Galy, J.; Magill, J.; Van Dam, H.; Valko, J.

    2002-06-01

    One can design a critical system with fissile material in the form of a thin layer on the inner surface of a cylindrical neutron moderator such as graphite or beryllium. Recently, we have investigated the properties of critical and near critical systems based on the use of thin actinide layers of uranium, plutonium and americium. The thickness of the required fissile layer depends on the type of fissile material, its concentration in the layer and on the geometrical arrangement, but is typically in the μm-mm range. The resulting total mass of fissile material can be as low as 100 g. Thin fissile layers have a variety of applications in nuclear technology—for example in the design neutron amplifiers for medical applications and "fast" islands in thermal reactors for waste incineration. In the present paper, we investigate the properties of a neutron booster unit for spallation sources and isotope production. In those applications a layer of fissile material surrounds the spallation source. Such a module could be developed for spallation targets foreseen in the MYRRHA (L. Van Den Durpel, H. Aı̈t Abderrahim, P. D'hondt, G. Minsart, J.L. Bellefontaine, S. Bodart, B. Ponsard, F. Vermeersch, W. Wacquier. A prototype accelerator driven system in Belgium: the Myrrha project, Technical Committee Meeting on Feasibility and Motivation for Hybrid concepts for Nuclear Energy generation and Transmutation, Madrid, Spain, September 17-19, 1997 [1]). or MEGAPIE (M. Salvatores, G.S. Bauer, G. Heusener. The MEGAPIE initiative: executive outline and status as per November 1999, MPO-1-GB-6/0_GB, 1999 [2]) projects. With a neutron multiplication factor of the booster unit in the range 10-20 (i.e. with a keff of 0.9-0.95), considerably less powerful accelerators would be required to obtain the desired neutron flux. Instead of the powerful accelerators with proton energies of 1 GeV and currents of 10 mA foreseen for accelerator driven systems, similar neutron fluxes can be obtained

  3. Characterization of an Am-Be PGNAA set-up developed for in situ liquid analysis: Application to domestic waste water and industrial liquid effluents analysis

    Energy Technology Data Exchange (ETDEWEB)

    Idiri, Z., E-mail: zmidiri@yahoo.f [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria); Mazrou, H. [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria); Amokrane, A. [Universite des Sciences et de la Technologie Houari Boumediene, Alger (Algeria); Bedek, S. [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria)

    2010-01-15

    A prompt gamma neutron activation analysis (PGNAA) set-up with an Am-Be source developed for in situ analysis of liquid samples is described. The linearity of its response was tested for chlorine and cadmium dissolved in water. Prompt gamma efficiency of the system has been determined experimentally using prompt gamma of chlorine dissolved in water and detection limits for different elements have been derived for domestic waste water. A methodology to analyze any kind of liquid is then proposed. This methodology consists mainly on using standards with water as bulk or in the case of absolute method, to use gamma efficiency determined with prompt gammas emitted by chlorine dissolved in water. To take into account the thermal neutron flux variations inside the samples, flux monitoring was carried out using a He-3 neutron detector placed at the external sample container surface. Finally, to correct for the differences in gamma attenuation, average gamma attenuations factors were calculated using MCNP5 code. This method was then checked successfully by determining cadmium in industrial phosphoric acid and our result was in good agreement with that obtained with inductively coupled plasma (ICP) method.

  4. Characterization of an Am-Be PGNAA set-up developed for in situ liquid analysis: Application to domestic waste water and industrial liquid effluents analysis

    Science.gov (United States)

    Idiri, Z.; Mazrou, H.; Amokrane, A.; Bedek, S.

    2010-01-01

    A prompt gamma neutron activation analysis (PGNAA) set-up with an Am-Be source developed for in situ analysis of liquid samples is described. The linearity of its response was tested for chlorine and cadmium dissolved in water. Prompt gamma efficiency of the system has been determined experimentally using prompt gamma of chlorine dissolved in water and detection limits for different elements have been derived for domestic waste water. A methodology to analyze any kind of liquid is then proposed. This methodology consists mainly on using standards with water as bulk or in the case of absolute method, to use gamma efficiency determined with prompt gammas emitted by chlorine dissolved in water. To take into account the thermal neutron flux variations inside the samples, flux monitoring was carried out using a He-3 neutron detector placed at the external sample container surface. Finally, to correct for the differences in gamma attenuation, average gamma attenuations factors were calculated using MCNP5 code. This method was then checked successfully by determining cadmium in industrial phosphoric acid and our result was in good agreement with that obtained with inductively coupled plasma (ICP) method.

  5. A technique to measure the neutron capture cross-sections of krypton isotopes

    International Nuclear Information System (INIS)

    For the measurement of the neutron capture cross-sections of noble gases an experimental technique was developed, where the probe material is irradiated in its liquid phase. To detect the capture gamma-rays a C6D6 liquid scintillator was constructed providing a defined sensitivity for capture events by applying an appropriate weighting function to the spectra. The capture cross-sections of natural Kr and 84Kr were measured relative to Au in the energy region between 5 keV and 240 keV. Values of Maxwellian averaged capture cross-sections at 5 keV <= kT <= 50 keV were derived, as they are needed for a quantitative understanding of the s-process of nucleosynthesis. By normalizing literature values of the isotopic cross-sections with the derived cross sections it was possible to determine the isotopic abundances produced in the s-process as well as the solar abundance of natural Kr. (orig.) 891 HSI/orig. 892 KN

  6. Shape coexistence in the neutron-deficient mercury isotopes studied through Coulomb excitation

    CERN Document Server

    Bree, Nick

    This thesis describes the analysis and results of a series of Coulomb-excitation experiments on even-even neutron-deficient mercury isotopes aimed at obtaining a more detailed description of shape coexistence. Two experimental campaigns have been undertaken in the Summer of 2007 and 2008. Pure beams of 182,184,186,188Hg were produced and accelerated at the REX-ISOLDE radioactive-beam facility, located at CERN (Geneva, Switzerland). The beams were guided to collide with a stable target to induce Coulomb excitation. The scattered particles were registered by a double-sided silicon strip detector, and the emitted gamma rays by the MINIBALL gamma-ray spectrometer. The motivation to study these mercury isotopes, focused around shape coexistence in atomic nuclei, is addressed in chapter 1, as well as an overview of the knowledge in this region of the nuclear chart. A theoretical description of Coulomb excitation is presented in the second chapter, while the third chapter describes the setup employed for the experim...

  7. Coulomb excitation of neutron-rich odd-$A$ Cd isotopes

    CERN Multimedia

    Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M

    We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...

  8. Study of isotopic fractions and abundances of the neutron-capture elements in HD 175305

    CERN Document Server

    Zhang, Jiang; Zhang, Bo; 10.1111/j.1365-2966.2009.15947.x

    2010-01-01

    The chemical abundances of metal-poor stars are excellent sources of information for setting new constraints on models of Galactic chemical evolution at low metallicities. In this paper we present an attempt to fit the elemental abundances observed in the bright, metal-poor giant HD 175305, and derive isotopic fractions using a parametric model. The observed abundances can be wellmatched by the combined contributions froms- and r-processmaterial. The component coefficients of the r- and s-processes are C1 = 3.220 and C3 = 1.134, respectively. The Smisotopic fraction in this star where the observed neutron-capture elements are produced is predicted to be f 152+154 =0.582,which suggests that, even though the r-process is predominantly responsible for the synthesis of the neutron-capture elements in the early Galaxy, the onset of the s-process had already occurred at this metallicity of [Fe/H] = -1.6.

  9. New neutron-rich isotope production in 154Sm+160Gd

    Science.gov (United States)

    Wang, Ning; Guo, Lu

    2016-09-01

    Deep inelastic scattering in 154Sm+160Gd at energies above the Bass barrier is for the first time investigated with two different microscopic dynamics approaches: improved quantum molecular dynamics (ImQMD) model and time dependent Hartree-Fock (TDHF) theory. No fusion is observed from both models. The capture pocket disappears for this reaction due to strong Coulomb repulsion and the contact time of the di-nuclear system formed in head-on collisions is about 700 fm/c at an incident energy of 440 MeV. The isotope distribution of fragments in the deep inelastic scattering process is predicted with the simulations of the latest ImQMD-v2.2 model together with a statistical code (GEMINI) for describing the secondary decay of fragments. More than 40 extremely neutron-rich unmeasured nuclei with 58 ≤ Z ≤ 76 are observed and the production cross sections are at the order of μb to mb. The multi-nucleon transfer reaction of Sm+Gd could be an alternative way to synthesize new neutron-rich lanthanides which are difficult to be produced with traditional fusion reactions or fission of actinides.

  10. New neutron-rich isotope production in $^{154}$Sm+$^{160}$Gd

    CERN Document Server

    Wang, Ning

    2016-01-01

    Deep inelastic scattering in $^{154}$Sm+$^{160}$Gd at energies above the Bass barrier is for the first time investigated with two different microscopic dynamics approaches: improved quantum molecular dynamics (ImQMD) model and time dependent Hartree-Fock (TDHF) theory. No fusion is observed from both models. The capture pocket disappears for this reaction due to strong Coulomb repulsion and the contact time of the di-nuclear system formed in head-on collisions is about 700 fm/c at an incident energy of 440 MeV. The isotope distribution of fragments in the deep inelastic scattering process is predicted with the simulations of the latest ImQMD-v2.2 model together with a statistical code (GEMINI) for describing the secondary decay of fragments. More than 40 extremely neutron-rich unmeasured nuclei with $58 \\le Z\\le 76$ are observed and the production cross sections are at the order of ${\\rm \\mu b}$ to mb. The multi-nucleon transfer reaction of Sm+Gd could be an alternative way to synthesize new neutron-rich lant...

  11. Measurement of fission yields far from the center of isotopic distributions in the thermal neutron fission of 235U

    International Nuclear Information System (INIS)

    The main purpose of this work was to measure independent yields, in the thermal neutron fission of 235U, of fission products which lie far from the centers of the isotopic and isobaric yield distributions. These measurements were used to test the predictions of semi-empirical systematics of fission yields and theoretical fission models. Delay times were measured as a function of temperature in the range 1200-2000degC. The very low delay times achieved in the present work permitted expanding the measurable region to the isotopes 147,148Cs and 99Rb which are of special interest in the present work. The delay times of Sr and Ba isotopes achieved were more than two orders of magnitude lower than values reported in the literature and thus short-lived isotopes of these elements could be separated for the first time by mass spectrometry. The half-lives of 147Ba, 148Ba, 149La and 149Ce were measured for the first time. The isotopic distributions of fission yields were measured for the elements Rb, Sr, Cs and Ba in the thermal neutron fission of 235U, those of 99Rb, 147Cs and 148Cs having been measured for the first time. A comparison of the experimental yields with the predictions of the currently accepted semi-empirical systematics of fission yields, which is the odd-even effect systematics, shows that the systematics succeeds in accounting for the strong odd-even proton effect and the weaker odd-even neutron effect and also in predicting the shape of the distributions in the central region. It is shown that prompt neutron emission broadens the distribution only slightly in the wing of heavy isotopes and more significantly in the wing of light isotopes. But the effect of prompt neutron emission cannot explain the large discrepancies existing between the predictions of fission models and the experimentally measured fission yield in the wings of the isotopic distributions. (B.G.)

  12. Lifetimes in neutron-rich Nd isotopes measured by Doppler profile method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    Lifetimes of the rotational levels in neutron-rich even-even Nd isotopes were deduced from the analysis of the Doppler broadened line shapes. The experiment was performed at Daresbury with the Eurogam array, which at that time consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. The source was in the form of a 7-mm pellet which was prepared by mixing 5-mg; {sup 248}Cm and 65-mg KCl and pressing it under high pressure. Events for which three or more detectors fired were used to construct a cubic data array whose axes represented the {gamma}-ray energies and the contents of each channel the number of events with that particular combination of {gamma}-ray energies. From this cubic array, one-dimensional spectra were generated by placing gates on peaks on the other two axes. Gamma-ray spectra of even-even Nd isotopes were obtained by gating on the transitions in the complimentary Kr fragments. The gamma peaks de-exciting states with I {>=} 12 h were found to be broader than the instrumental line width due to the Doppler effect. The line shapes of they-ray peaks were fitted separately with a simple model for the feeding of the states and assuming a rotational band with constant intrinsic quadruple moment and these are shown in Fig. I-27. The quadrupole moments thus determined were found to be in good agreement with the quadrupole moments measured previously for lower spin states. Because of the success of this technique for the Nd isotopes, we intend to apply this technique to the new larger data set collected with the Eurogam II array. The results of this study were published.

  13. Utilization of a TRIGA nuclear reactor for neutron activation analysis and isotope production

    International Nuclear Information System (INIS)

    In this paper, some examples of utilization of the TRIGA reactor at Casaccia research center of ENEA are described, including neutron activation analysis (NAA), isotope production and tritium release studies. 1) NAA - Determination of trace elements by NAA has been performed, in the last years upon a variety of matrices: a) environmental: suspended particulate matter (SPM) and sediments collected in some Italian seas and rivers were analyzed for about 30 elements. Different types of filters were also tested to choose the most suitable for the collection of SPM. b) forensic: many applications of NAA have been performed on request of Italian Courts for determination of gunshot residues; firing distances were also determined in some cases. c) agricultural: the uptake of Zn and Co by cereals has been studied in pot in co-operation with the Istituto per la Cerealicoltura of Rome. d) geological: some USGS reference materials were analyzed by thermal and epithermal NAA, for evaluating accuracy and precision of both methods. Rock samples from the basaltic plateau of Kenya were then analyzed by ENAA, chiefly for rare earth elements, whose concentration patterns can give useful informations about petrogenesis. e) reference materials: several elements have been determined in lake and river sediment samples and in three plant materials (tobacco, apple-tree and peach-tree), in order to provide data for their certification as reference materials to be used in different fields. f) nuclear materials: trace elements have been determined in LiAlO2 to be used in the blanket of fusion reactors, as well as in cements for building nuclear plants, in order to evaluate the activity at the time of plant decommissioning. 2) Isotope production a) A program for the utilization of TRIGA reactor at Casaccia to prepare a 191m-Ir generator to be used in pediatric angiography has been drawn up. b) Preparation of 18-F to be used in positron emission tomography (PET) for studies of cerebral diseases

  14. The production of unknown neutron-rich isotopes in $^{238}$U+$^{238}$U collisions at near-barrier energy

    CERN Document Server

    Zhao, Kai; Zhang, Yingxun; Wang, Ning; Li, Qingfeng; Shen, Caiwan; Wang, Yongjia; Wu, Xizhen

    2016-01-01

    The production cross sections for primary and residual fragments with charge number from $Z$=70 to 120 produced in the collision of $^{238}$U+$^{238}$U at 7.0 MeV/nucleon are calculated by the improved quantum molecular dynamics (ImQMD) model incorporated with the statistical evaporation model (HIVAP code). The calculation results predict that about sixty unknown neutron-rich isotopes from element Ra ($Z$=88) to Db ($Z$=105) can be produced with the production cross sections above the lower bound of $10^{-8}$ mb in this reaction. And almost all of unknown neutron-rich isotopes are emitted at the laboratory angles $\\theta_{lab}\\leq$ 60$^\\circ$. Two cases, i.e. the production of the unknown uranium isotopes with $A\\geq$ 244 and that of rutherfordium with $A\\geq$ 269 are investigated for understanding the production mechanism of unknown neutron-rich isotopes. It is found that for the former case the collision time between two uranium nuclei is shorter and the primary fragments producing the residues have smaller...

  15. Determination of neutrons dose by spectrometry analysis of the isotope 24 of the sodium in the blood

    International Nuclear Information System (INIS)

    The neutron films can be saturated in the case of accidental irradiation so it is necessary to find an other way to assess the dose in the case of saturation of the film. It is possible to estimate this dose by the concentration measurement of the isotope 24 of the sodium in the blood. The activity of the Na24 results from the capture by Na23 the atoms of the neutrons thermalized by the human body, this activation is proportional to the neutrons fluence, quantity that can be linked to the absorbed neutrons dose, with appropriate factors. However, it is not possible to estimate H*(10) only by measuring the concentration in Na24 in blood, at the very most this measure allows to establish a maximal or minimum neutrons dose. On the other hand, in the case of an irradiation in a known field, this measure allows to link the neutron dose equivalent to Na24 activity in blood. In the other cases, it is necessary to reconstruct the accident in order to measure the energy distribution of the neutrons spectrum. (N.C.)

  16. Study on bioavailability of dietary iron of women by using activable isotopic tracer and neutron activation analysis techniques

    International Nuclear Information System (INIS)

    The bioavailability of diet iron of 10 healthy young women in Beijing area is studied by using two enriched isotopes 54Fe and 58Fe, and neutron activation analysis techniques. The abundance of 54Fe and 58Fe is 61.4% and 23.4%, respectively. In additional, the atomic absorption spectrometry is employed to measure total iron in fecal samples. Dysprosium, rarely absorbed by human body, is used to monitor the residence time of tracer isotopes in order to collect the fecal samples completely. The results show that the bioavailability of dietary iron in young women is (14.9 +- 3.9)%

  17. Uranium content and 235U/238U isotopic ratio in dental porcelain powders determined by neutron activation analysis

    International Nuclear Information System (INIS)

    The uranium contents and 235U/238U isotopic ratios in 48 dental porcelain powders of 8 brands marketed in Japan were determined by non-destructive neutron activation analysis. The photopeak counts of 277.6 keV of 239Np formed by the 238U(n,γ)239U (yield to)239Np + β- reaction and at 1.595.2 keV of 140La produced by 235U fission were measured with a Ge(Li) semiconductor detector system to determine the uranium content and 235U/238U isotopic ratio. The results of the analysis are tabulated and their significance discussed. (author)

  18. Production of neutron-rich isotopes by fragmentation of 80 MeV/nucleon 59Co beam

    International Nuclear Information System (INIS)

    using a primary beam of 59Co at 80 MeV/nucleon impinging on a berilium target, production cross-sections of neutron-rich fragments from projectile fragmentation have been measured at the Projectile Fragment Separator RIPS at the Institute of Physical and Chemical Research (RIKEN - Japan). The experimental production cross-sections ranging from Na to Ti for isotopes close to stability as well as for fragments at the neutron drip-line are compared to the results of the empirical parametrization EPAX

  19. Energy dependence of mass, charge, isotopic, and energy distributions in neutron-induced fission of 235U and 239Pu

    Science.gov (United States)

    Pasca, H.; Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kim, Y.

    2016-05-01

    The mass, charge, isotopic, and kinetic-energy distributions of fission fragments are studied within an improved scission-point statistical model in the reactions 235U+n and 239Pu+n at different energies of the incident neutron. The charge and mass distributions of the electromagnetic- and neutron-induced fission of 214,218Ra, 230,232,238U are also shown. The available experimental data are well reproduced and the energy-dependencies of the observable characteristics of fission are predicted for future experiments.

  20. Characterization of Mg B4 O7: Dy thermoluminescent phosphor for application in thermal neutron detection

    International Nuclear Information System (INIS)

    Some parameters related to the production of Magnesium Borate doped with Dysprosium (Mg B4 O7: Dy) were studied, in order to increase the phosphor thermoluminescence sensitivity and verify its characteristics for thermal neutron detection. This phosphor was chosen due to presence of boron (B). The isotope 10 B (isotopic abundance of 19,8%) has a thermal neutron cross section of 3837 barns for the 10 B (n,α)7 Li reaction. The irradiation set up consists of an 241 Am-Be neutron source surrounded by a lead filter for shielding against the low energy gamma rays, and a paraffin block for neutron moderation. The results obtained show the utilizing feasibility of this material in neutron personal monitoring, taking into account its low production cost, adequate sensibility, linear response within the dose range used in personal monitoring and low T L response fading. (author)

  1. On the origin of the anomalous behaviour of 2+ excitation energies in the neutron-rich Cd isotopes

    International Nuclear Information System (INIS)

    Recent experimental results obtained using β decay and isomer spectroscopy indicate an unusual behaviour of the energies of the first excited 2+ states in neutron-rich Cd isotopes approaching the N=82 shell closure. To explain the unexpected trend, changes of the nuclear structure far-off stability have been suggested, namely a quenching of the N=82 shell gap already in 130Cd, only two proton holes away from doubly magic 132Sn. We study the behaviour of the 2+ energies in the Cd isotopes from N=50 to N=82, i.e. across the entire span of a major neutron shell using modern beyond mean field techniques and the Gogny force. We demonstrate that the observed low 2+ excitation energy in 128Cd close to the N=82 shell closure is a consequence of the doubly magic character of this nucleus for oblate deformation favoring thereby prolate configurations rather than spherical ones

  2. Neutron capture cross sections of the krypton isotopes and the s-process branching at 79Se

    International Nuclear Information System (INIS)

    The input data for an analysis of the s-process branching at 79Se have been significantly improved. The neutron capture cross sections for the stable krypton isotopes (except 86Kr) were measured between 3 and 240 keV neutron energy. In addition, statistical model calculations of the (n,γ)-cross sections for all isotopes involved in this branching were performed. With these data and with other experimental results from literature a recommended set of Maxwellian average cross sections was established in the mass region 77< A<85. The relevant decay parameters of the involved unstable nuclei and the parameters for the s-process model are discussed as well. On this basis the following aspects are investigated: the temperature during s-process, the decomposition into s- and r-process contributions and the solar krypton abundance. (orig.)

  3. Study on bioavailability of zinc for children's diet by using activable isotopic tracer 70Zn and neutron activation analysis techniques

    International Nuclear Information System (INIS)

    Bioavailability of zinc for three groups (low amount of diet zinc, balance amount of diet zinc and high amount of diet zinc) of children's diet is studied by using activable isotopic tracer 70Zn and neutron activation analysis techniques. The results indicate that the fractional absorption of zinc from balance diet zinc group is the highest, up to 33.9%. A procedure of pre-irradiation concentration zinc for fecal samples using anion exchanger is developed, and the enriched 70Zn with isotopic abundance of 18.3% is used for tracer. The mass ratios between 70Zn and 68Zn or 64Zn and their contents between natural zinc and enriched zinc are used to calculate the bioavailability of zinc. Instrumental neutron activation analysis of 64Zn of each original fecal samples and pre-irradiation concentrated zinc samples are used to normalize the chemical yield in order to reduce the uncertainty during the chemical separation procedure

  4. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    International Nuclear Information System (INIS)

    Neutron capture cross sections in the keV neutron energy region are the key nuclear physics input to study the astrophysical slow neutron capture process. In the past years, a series of neutron capture cross section measurements has been performed at the neutron time-of-flight facility nTOF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed

  5. Mass measurement and structure studies of neutron-rich isotopes of Zn, Ni, Fe

    International Nuclear Information System (INIS)

    With the Orsay MP Tandem, the reaction (14C,16O) on 58-60-62-64Ni, 64-66-68-70Zn, 74-76Ge and 82Se targets, and the reaction (14C,15O) on 60-62-64Ni, 68-70Zn, 76Ge targets, have been investigated at 72 MeV bombarding energy. The mass excess of neutron rich nuclei: 63Fe (-55.19+-.06MeV), 69Ni(-60.14+-.06 MeV), 75Zn(.62.7+-08 MeV) have been measured for the first time, and those of 62Fe, 68Ni, 74Zn, 80Ge have been remeasured. A new equipment has been designed in order to perform measurements at zero degree. From the angular distribution around 00 for the 70Zn(14C,16O) reaction, the first state of 68Ni observed for the first time (1.77 MeV +- .04 MeV) has been shown to be a 0+. This result establishes a new case of 21+ - 02+ inversion. The systematics of the (14C, 16O) measurements on the even Ni and Zn isotopes have shown a different behaviour with two series. For the Ni → Fe (g.s.) transitions, the ratio σsub(exp)/σsub(DWBA) increases by a factor of four when the neutron number varies from 30 to 36. Whereas for the Zn → Ni (gs) transitions this ratio remains constant for the first three isotopes and decrease by a factor of two when N=40. For the Ni → Fe transitions, axial and spherical symmetries have been used. In agreement with the shell model no change are found with the spherical symmetry. For the axial symmetry a variation is observed but strongly dapendant of the sub-shell. Hence no clear conclusion can be deduced for the cross section estimate. For the Zn → Ni transitions, the spherical symmetry has been used. One configuration prevails, leading to a qualitative agreement with the experimental results

  6. Time-of-flight mass measurements of neutron-rich chromium isotopes up to N =40 and implications for the accreted neutron star crust

    Science.gov (United States)

    Meisel, Z.; George, S.; Ahn, S.; Bazin, D.; Brown, B. A.; Browne, J.; Carpino, J. F.; Chung, H.; Cyburt, R. H.; Estradé, A.; Famiano, M.; Gade, A.; Langer, C.; Matoš, M.; Mittig, W.; Montes, F.; Morrissey, D. J.; Pereira, J.; Schatz, H.; Schatz, J.; Scott, M.; Shapira, D.; Sieja, K.; Smith, K.; Stevens, J.; Tan, W.; Tarasov, O.; Towers, S.; Wimmer, K.; Winkelbauer, J. R.; Yurkon, J.; Zegers, R. G. T.

    2016-03-01

    We present the mass excesses of Cr-6459, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48 (44 ) MeV. We find a significantly different two-neutron separation energy S2 n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N =38 . Additionally, we extend the S2 n trend for chromium to N =40 , revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the f p shell, including the g9 /2 and d5 /2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A =64 isobaric chain, resulting in a cooler than expected accreted neutron star crust. This reduced heating is found to be due to the >1 -MeV reduction in binding for 64Cr with respect to values from commonly used global mass models.

  7. Evaluation of the determination of iodine in drinking well water by neutron activation analysis and separation by isotope exchange

    International Nuclear Information System (INIS)

    The determination of total iodine in drinking and well water by neutron activation analysis and separation of 128I(T=25.0 min) by isotope exchange has been examined at the 5-15 ng.ml-1 level. Using the Lazy Suzan of a Triga Mark-II reactor, the capacity is ≤5 samples per hour at a precision of 15-20% per aliquot and no apparent systematic bias. (author) 6 refs.; 1 tab

  8. The development of an automatic sample-changer and control instrumentation for isotope-source neutron-activation analysis

    International Nuclear Information System (INIS)

    An automatic sample-changer was developed at the Council for Mineral Technology for use in isotope-source neutron-activation analysis. Tests show that the sample-changer can transfer a sample of up to 3 kg in mass over a distance of 3 m within 5 s. In addition, instrumentation in the form of a three-stage sequential timer was developed to control the sequence of irradiation transfer and analysis

  9. Determination of activable isotopic tracers of zinc by neutron activation analysis for study of bioavailability of zinc

    International Nuclear Information System (INIS)

    A procedure of pre-irradiation concentration of zinc in fecal samples using anion exchanger was developed for the study of the bioavailability of zinc by neutron activation analysis. The mass ratios between 70Zn and 68Zn, or 64Zn and their contents between natural zinc and enriched zinc are used to calculate the bioavailability of zinc when the abundance of the isotope 70Zn is not high enough. (author) 9 refs.; 1 fig.; 2 tabs

  10. High neutron flux quality for irradiation and BCNT conditions

    International Nuclear Information System (INIS)

    This paper presents methods for characterising the neutron field in irradiation and boron neutron capture therapy (BNCT) facilities, applications for which a high flux quality is needed. The irradiation facility considered consists of an isotopic (Am-Be) neutron source in a cylindrical cavity bored inside a solid paraffin cube measuring 51·51·51 cm, thus constituting a neutron Howitzer. The neutron flux distribution within the cavity above this source was investigated by measurements of aluminium foil activation and by calculations with the MCNP-4C code. The BNCT calculations were performed for different channel radii. Results from measurements and calculations are in good agreement despite the uncertainties in identifying the exact energies at which the two reactions measured, 27Al(n,γ)28Al and 27Al(n, p)27Mg, take place. The study provided useful information about the optimal irradiation and BNCT conditions. (author)

  11. Impact of statistical uncertainty of the neutron spectrum in the isotopic evolution of fuel; Impacto de la incertidumbre estadistica del espectro neutronico en la evoluacion isotopica del combustible

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, P.

    2012-07-01

    The results obtained and presented in this study for different calculation conditions (number of stories, number of steps burning, etc.) and their simultaneous impact on neutron spectrum and isotopic composition and a methodology is proposed to determine the minimum parameters for calculation given uncertainty in the results of isotopic composition with high burnup, both UO{sub 2} and MOX fuel.

  12. Extension of the nuclear mass surface for neutron-rich isotopes of argon through iron

    Science.gov (United States)

    Meisel, Zachary Paul

    Nuclear mass measurement has maintained an important position in the field of nuclear physics for a little over a century. Nuclear masses provide key evidence of the structural transformation of nuclei away from the valley of beta-stability and are essential input for many simulations of extreme astrophysical environments. However, obtaining these masses is often a challenging endeavor due to the low production cross sections and short half-lives of the exotic nuclei which are of particular interest. To this end, the time-of-flight mass measurement technique has been developed to obtain the masses of several nuclei at once to precisions of 1 part in 105 with virtually no half-life limitation. This dissertation contains a description of the experiment, analysis, and results of the second implementation of the time-of-flight nuclear mass measurement technique at the National Superconducting Cyclotron Laboratory. 18 masses were obtained for neutron-rich isotopes of argon through iron, where the masses of 48Ar, 49Ar, 56Sc, 57Sc, 64Cr, 67Mn, and 69Fe were measured for the first time. These newly obtained masses were applied to outstanding problems in nuclear structure and nuclear astrophysics, resulting in significant scientific advances. The measurement results for 48Ar and 49Ar, which were found to have atomic mass excesses of -22.28(31) MeV and -17.8(1.1) MeV, respectively, provide strong evidence for the closed shell nature of neutron number N = 28 in argon. It follows that argon is therefore the lowest even-Z element exhibiting the N = 28 closed shell. The masses of 64Cr, 67 Mn, and 69Fe, which were found to have atomic mass excesses of -33.48(44) MeV, -34.09(62) MeV, and -39.35(60) MeV, respectively, show signs of nuclear deformation occurring around the N = 40 subshell. In addition, we found 64Cr is substantially less bound than predicted by global mass models that are commonly used in nuclear astrophysics simulations, resulting in a significant reduction in the

  13. Microscopic study of low-lying yrast spectra and deformation systematics in neutron-rich 98−106Sr isotopes

    Indian Academy of Sciences (India)

    Anil Chandan; Suram Singh; Arun Bharti; S K Khosa

    2009-10-01

    Variation-after-projection (VAP) calculations in conjunction with Hartree–Bogoliubov (HB) ansatz have been carried out for = 98–106 strontium isotopes. In this framework, the yrast spectra with ≥ 10+, (2) transition probabilities, quadrupole deformation parameter and occupation numbers for various shell model orbits have been obtained. The results of the calculation for yrast spectra give an indication that it is important to include the hexadecapole–hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in Sr isotopes. Besides this, it is also found that the simultaneous polarization of 3/2 and 5/2 proton subshells is a significant factor in making a sizeable contribution to the deformation in neutron-rich Sr isotopes.

  14. Penning trap mass spectrometry of neutron-rich Fe and Co isotopes around N=40 with the LEBIT mass spectrometer

    International Nuclear Information System (INIS)

    Penning trap mass spectrometry is presented as a complementary tool to nuclear spectroscopy experiments for the study of nuclear structure in the vicinity of N=40, Z=28. High-precision mass measurements of the 63-66Fe and 64-67Co isotopes have been carried out with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. The newly obtained mass values for 66Fe and 67Co are presented, together with the previously reported LEBIT mass measurements in this region. In the case of 65Fe the existence of a new isomer is reported, and an isomer recently discovered by decay spectroscopy in 67Co is confirmed. Relative mass uncertainties as low as 4x10-8 are obtained. All mass values are found to be in good agreement with previous experimental results with the exception of 64Co, where a 5σ deviation is observed. Using these data the two neutron separation energies S2n are calculated. However, the large error bars in the mass values of the neighbor Fe and Co isotopes with N>40 complicate the validation of a weak subshell closure at N=40 for the Co isotopes or the possible reduction in the neutron shell gap in the case of the Fe isotopes, in accordance with the theoretical predictions of an onset of deformation in the region.

  15. Stellar (n ,γ ) cross sections of neutron-rich nuclei: Completing the isotope chains of Yb, Os, Pt, and Hg

    Science.gov (United States)

    Marganiec, J.; Dillmann, I.; Domingo-Pardo, C.; Käppeler, F.

    2014-12-01

    The (n ,γ ) cross sections of the most neutron-rich stable isotopes of Yb, Os, Pt, and Hg have been determined in a series of activation measurements at the Karlsruhe 3.7 MV Van de Graaff accelerator, using the quasistellar neutron spectrum for k T =25 keV that can be produced with the 7Li(p ,n ) 7Be reaction. In this way, Maxwellian averaged cross sections could be directly obtained with only minor corrections. After irradiation the induced activities were counted with a HPGe detector via the strongest γ -ray lines. The stellar neutron capture cross sections of Yb,176174, Os,192190, Pt,198196, and Hg,204202, extrapolated to k T =30 keV, were found to be 157 ±6 mb, 114 ±8 mb, 278 ±11 mb, 160 ±7 mb, 171 ±19 mb, 94 ±4 mb, 62 ±2 mb, and 32 ±15 mb, respectively. In the case of 196Pt the partial cross section to the isomeric state at 399.5 keV could be determined as well. With these results the cross section data for long isotopic chains could be completed for a discussion of the predictive power of statistical model calculations towards the neutron-rich and proton-rich sides of the stability valley.

  16. Study the structure of neutron deficient carbon isotopes: 10C and 11C. Elastic and inelastic scattering on proton target

    International Nuclear Information System (INIS)

    This work is devoted to the study of the structure of neutron-deficient carbon isotopes: 10C and 11C. A theoretical model predicts a special behaviour for these nuclei: different deformations for neutron and proton densities. To test these predictions and to obtain information on the structure of these nuclei, we measured angular distribution for elastic and inelastic scattering on proton target with inverse kinematics at 40 MeV per nucleon. The angular distribution is deduced from the proton energy and angle scattering, measured by the MUST detector. Experimental set-up is completed with plastic detectors for scattered nucleus identification and with two CATS detectors for measurement of position and angle for each beam particle on the target. Angular distributions are calculated with an analytic method. This method is tested with a simulation and with 12C + p scattering analysis. Angular distributions are analysed in terms of a complex microscopic potential JLM with different microscopic matter densities. Elastic scattering gives an information on 10C and 11C matter root mean square radii. Both radii are larger than the one for the stable 12C isotope. Inelastic scattering is treated in DWBA approximation with microscopic transition densities. 10C inelastic scattering gives an information on neutron contribution of nucleus excitation. With 11C inelastic scattering, we could constrain transition densities and we could extract an information on the type of the transition. However, it is very difficult to confirm or to annul predictions of different deformations for proton and neutrons densities. (author)

  17. Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

    International Nuclear Information System (INIS)

    The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron rich Zn isotopes (A=71 to 81) lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of 81Zn has been measured directly for the rst time. The half-lives of the nuclides ranged from 46.5 h (72Zn) down to 290 ms (81Zn). In case of all the nuclides, the relative mass uncertainty (Δm=m) achieved was in the order of 10-8 corresponding to a 100-fold improvement in precision over previous measurements. (orig.)

  18. Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

    Energy Technology Data Exchange (ETDEWEB)

    Baruah, Sudarshan

    2008-07-15

    The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron rich Zn isotopes (A=71 to 81) lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of {sup 81}Zn has been measured directly for the rst time. The half-lives of the nuclides ranged from 46.5 h ({sup 72}Zn) down to 290 ms ({sup 81}Zn). In case of all the nuclides, the relative mass uncertainty ({delta}m=m) achieved was in the order of 10{sup -8} corresponding to a 100-fold improvement in precision over previous measurements. (orig.)

  19. Triaxial shapes in the ground states of even-even neutron-rich Ru isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    Partial level schemes for {sup 108,110,112}Ru, and {sup 114}Ru about which nothing was previously known, were determined from the measurement of prompt, triple-gamma coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 249}Cm source, mixed with 65-mg KCl and pressed in the form of a 7-mm diameter pellet, was used for the experiment. Prompt {gamma} rays emitted from the fission fragments were detected with the Eurogam array at Daresbury, which at that time consisted of 45 Compton suppressed Ge detectors and 5 LEPS spectrometers. Transitions in Ru were identified by gating on {gamma} rays in the complementary Te fragments. Figure I-25 shows the technique used to identify the previously unknown transitions in {sup 114}Ru and its partial level scheme. High spin states up to spin 10 h were observed and the {gamma}-ray branching ratios were determined. The ratios of electric quadrupole transition probabilities deduced from the experimental branching ratios were found to be in good agreement with the predictions of a simple model of rigid triaxial rotor. Our analysis shows that gamma deformation in Ru isotopes is increasing with the neutron number and the gamma value for {sup 112}Ru and {sup 114}Ru is {approximately} 25 degrees. This is one of the highest gamma values encountered in nuclei, suggesting soft triaxial shapes for {sup 112}Ru and {sup 114}Ru. The results of this investigation were published.

  20. Study of the Neutron Deficient Pb and Bi Isotopes by Simultaneous Atomic- and Nuclear-Spectroscopy

    CERN Multimedia

    Kessler, T

    2002-01-01

    We propose to study systematically nuclear properties of the neutron deficient lead $^{183-189}$Pb, $^{191g}$Pb, $^{193g}$Pb and bismuth isotopes $^{188-200}$Bi by atomic spectroscopy with the ISOLDE resonance ionisation laser ion source (RILIS) combined with simultaneous nuclear spectroscopy at the detection set-up. The main focus is the determination of the mean square charge radii of $^{183-190}$Pb and $^{188-193}$Bi from which the influence of low-lying intruder states should become obvious. Also the nuclear spin and magnetic moments of ground-states and long-lived isomers will be determined unambiguously through evaluation of the hyperfine structure, and new isomers could be discovered. The decay properties of these nuclei can be measured by $\\alpha$-$\\gamma$ and $\\beta$-$\\gamma$ spectroscopy. With this data at hand, possible shape transitions around mid-shell at N$\\sim$104 will be studied. This data is crucial for the direct test of nuclear theory in the context of intruder state influence (e.g. energy ...

  1. Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of $^{96}$Sr

    CERN Multimedia

    Clement, E; Siem, S; Czosnyka, T

    2007-01-01

    The nuclei in the mass region A $\\cong$ 100 around Sr and Zr show a dramatic change of the nuclear ground-state shape from near spherical for N $\\leq$ 58 to strongly deformed for N $\\geq$ 60. Theoretical calculations predict the coexistence of slightly oblate and strongly prolate deformed configurations in the transitional region. However, excited rotational structures based on the highly deformed configuration, which becomes the ground state at N = 60, are not firmly established in the lighter isotopes, and the earlier interpretation of a very abrupt change of shape has been challenged by recent experimental results in favor of a rather gradual change. We propose to study the electromagnetic properties of the neutron-rich nucleus $_{38}^{96}$Sr$_{58}$ by low-energy Coulomb excitation using the REX-ISOLDE facility and the MINIBALL detector array. Both transitional and diagonal matrix elements will be extracted, resulting in a complete description of the transition strengths and quadrupole moments of the low-l...

  2. Pigmy resonance in monopole response of neutron-rich Ni isotopes ?

    CERN Document Server

    Hamamoto, Ikuko

    2014-01-01

    The RPA monopole strength as well as the unperturbed particle-hole excitation strength is studied, in which the strength in the continuum is properly treated without discretizing unbound particle spectra. The model is the sef-consistent Hartree-Fock calculation and the RPA Green's function method with Skyrme interactions. Numerical examples are the Ni-isotopes, especially $^{68}_{28}$Ni$_{40}$, in which an experimental observation of low-lying socalled "pigmy resonance" with an appreciable amount of monopole strength at 12.9 $\\pm$ 1.0 MeV was recently reported. In the present study it is concluded that sharp monopole peaks with the width of the order of 1 MeV can hardly be expected for $^{68}$Ni in that energy region. Instead, a broad shoulder of monopole strength consisting of neutron excitations to non-resonant one-particle states (called "threshold strength") with relatively low angular-momenta $(\\ell, j)$ is obtained in the continuum energy region above the particle threshold, which is considerably lower ...

  3. Skyrme-Hartree-Fock description of the nuclear structure in Ca isotopes. Pt.2: Neutron halo, skin and particles in the classically forbidden area

    International Nuclear Information System (INIS)

    The pure-neutron-matter together with the neutron skin or halo in Ca isotopes is studied using the Skyrme-Hartree-Fock model. It is shown that the pure-neutron-matter thickness depends not only on the Fermi levels of the neutrons, but also on the orbital angular momentum of the valence neutrons. A new definition for the thickness of pure-neutron-matter is proposed. Particles in classically forbidden area are also studied. The number of neutrons in the classically forbidden area increases with mass number A, because of the increase in the number of neutrons occupied in the weakly bound open shell. The number of protons in the classically forbidden area, in contrast, decreases with mass number A, because the orbits of protons become more deeply bound. It is shown that the number of particles in the classically forbidden area can give information on the appearance of the halo or skin

  4. First-forbidden $\\mathbf{\\beta}$-decay rates, energy rates of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions for neutron-rich nickel isotopes

    CERN Document Server

    Nabi, Jameel-Un; Iftikhar, Zafar

    2016-01-01

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar $\\beta$-decay rates, energy rate of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the $r$-matter flow.

  5. Experimental investigation of decay properties of neutron deficient $^{116-118}$Ba isotopes and test of $^{112-115}$Ba beam counts

    CERN Multimedia

    We propose to study decay of neutron deficient isotopes $^{116-118}$Ba using Double Sided Silicon Strip Detector (DSSSD). To study delayed-proton and $\\alpha$-decay branching ratios of $^{116-118}$Ba are of special interest because of their vicinity to the proton drip line. The nuclear life-times and properties of the proton unstable states of Cs isotopes, populated through decay of $^{116-118}$Ba isotopes will be measured. In addition to that we propose beam development of $^{112-115}$Ba to study exotic decay properties of these neutron deficient nuclei and to search for super-allowed $\\alpha$-decay in future.

  6. Production of neutron-rich isotopes by cold fragmentation in the reaction {sup 197}Au + Be at 950 A MeV

    Energy Technology Data Exchange (ETDEWEB)

    Benlliure, J.; Pereira, J. [Universidad de Santiago de Compostela (Spain)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Schmidt, K.H.; Cortina-Gil, D.; Enqvist, T.; Heinz, A.; Junghans, A.R. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Farget, F. [Institut de Physique Nucleaire, 91 - Orsay (France); Taieb, J. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Institut de Physique Nucleaire, 91 - Orsay (France)

    1999-09-01

    The production cross sections and longitudinal-momentum distributions of very neutron-rich isotopes have been investigated in the fragmentation of a 950 A MeV {sup 179}Au beam in a beryllium target. Seven new isotopes ({sup 193}Re, {sup 194}Re, {sup 191}W, {sup 192}W, {sup 189}Ta, {sup 187}Hf and {sup 188}Hf) and the five-proton-removal channel were observed for the first time. The reaction mechanism leading to the formation of these very neutron-rich isotopes is explained in terms of the cold-fragmentation process. An analytical model describing this reaction mechanism is presented. (orig.)

  7. Schottky mass measurement of the 208Hg isotope: implication for the proton-neutron interaction strength around doubly magic 208Pb.

    Science.gov (United States)

    Chen, L; Litvinov, Yu A; Plass, W R; Beckert, K; Beller, P; Bosch, F; Boutin, D; Caceres, L; Cakirli, R B; Carroll, J J; Casten, R F; Chakrawarthy, R S; Cullen, D M; Cullen, I J; Franzke, B; Geissel, H; Gerl, J; Górska, M; Jones, G A; Kishada, A; Knöbel, R; Kozhuharov, C; Litvinov, S A; Liu, Z; Mandal, S; Montes, F; Münzenberg, G; Nolden, F; Ohtsubo, T; Patyk, Z; Podolyák, Zs; Propri, R; Rigby, S; Saito, N; Saito, T; Scheidenberger, C; Shindo, M; Steck, M; Ugorowski, P; Walker, P M; Williams, S; Weick, H; Winkler, M; Wollersheim, H-J; Yamaguchi, T

    2009-03-27

    Time-resolved Schottky mass spectrometry has been applied to uranium projectile fragments which yielded the mass value for the 208Hg (Z=80, N=128) isotope. The mass excess value of ME=-13 265(31) keV has been obtained, which has been used to determine the proton-neutron interaction strength in 210Pb, as a double difference of atomic masses. The results show a dramatic variation of the strength for lead isotopes when crossing the N=126 neutron shell closure, thus confirming the empirical predictions that this interaction strength is sensitive to the overlap of the wave functions of the last valence neutrons and protons. PMID:19392270

  8. Study of room-return neutrons

    International Nuclear Information System (INIS)

    The coefficient that relates the neutron source strength and inner room surface area with the thermal neutron fluence rates has been calculated for neutrons whose energy goes from 1eV to 20MeV. This coefficient was calculated using Monte Carlo methods for 150, 200 300, 535.24, 832.10 and 1010cm-radius spherical cavity with and without air. In the calculations monoenergetic neutron sources were located at the center of cavity and, along the spherical cavity radius, neutron spectra were determined at several source-to-detector distances. From the neutron spectra the thermal neutron (E=<0.414eV) contribution was calculated and several coefficients were estimated. A weighted average of all coefficients was estimated being 5.6+/-0.1, this is the c-value for the case of rooms without air, and 4.8+/-0.4, for rooms with air. In the aim to compare the results with monoenergetic neutrons, calculations were also performed using two isotopic neutron sources, Cf252 and AmBe241 in vacuum

  9. Estudio de la anisotropía de una fuente de Am-Be de 111 GBq

    OpenAIRE

    Méndez Villafañe, Roberto; Gallego Díaz, Eduardo F.; Lorente Fillol, Alfredo; Ibáñez, Sviatovslav; Guerrero Araque, Jorge Enrique

    2011-01-01

    Se ha estudiado la anisotropía de una fuente de Am-Be de 111 GBq (3Ci) mediante el uso de un pequeño motor que permite girar paso a paso la fuente situada en su posición de irradiación habitual. Las medidas se han realizado con un contador proporcional de 3He alojado en el interior de una esfera moderadora de 8” correspondiente a un sistema de espectrometría de esferas Bonner. Se reportan los resultados obtenidos y el factor de anisotropía determinado para esta fuente.

  10. Half-lives and branchings for {\\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

    CERN Document Server

    Hosmer, P; Aprahamian, A; Arndt, O; Clement, R R C; Estrade, A; Farouqi, K; Kratz, K -L; Liddick, S N; Lisetskiy, A F; Mantica, P F; Möller, P; Mueller, W F; Montes, F; Morton, A C; Ouellette, M; Pellegrini, E; Pereira, J; Pfeiffer, B; Reeder, P; Santi, P; Steiner, M; Stolz, A; Tomlin, B E; Walters, W B; Wöhr, A; 10.1103/PhysRevC.82.025806

    2010-01-01

    The {\\beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {\\beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {\\beta}-delayed neutron emission (Pn values) for 74Co (18 +/- 15%) and 75-77Ni (10 +/- 2.8%, 14 +/- 3.6%, and 30 +/- 24%, respectively) for the first time, and remeasured the Pn values of 77-79Cu, 79,81Zn, and 82Ga. For 77-79Cu and for 81Zn we obtain significantly larger Pn values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of 75Co (30 +/- 11 ms) and 80Cu (170+110 -50 ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is bet...

  11. Time-of-flight mass measurements of neutron-rich chromium isotopes up to N = 40 and implications for the accreted neutron star crust

    CERN Document Server

    Meisel, Z; Ahn, S; Bazin, D; Brown, B A; Browne, J; Carpino, J F; Chung, H; Cyburt, R H; Estradé, A; Famiano, M; Gade, A; Langer, C; Matoš, M; Mittig, W; Montes, F; Morrissey, D J; Pereira, J; Schatz, H; Schatz, J; Scott, M; Shapira, D; Sieja, K; Smith, K; Stevens, J; Tan, W; Tarasov, O; Towers, S; Wimmer, K; Winkelbauer, J R; Yurkon, J; Zegers, R G T

    2016-01-01

    We present the mass excesses of 59-64Cr, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48(44) MeV. We find a significantly different two-neutron separation energy S2n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N=38. Additionally, we extend the S2n trend for chromium to N=40, revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the fp shell, including the g9/2 and d5/2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A=64 isobaric...

  12. Elemental and isotopic characterization of Japanese and Philippine polished rice samples using instrumental neutron activation analysis and isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    Rice is a staple food for most Asian countries such as the Philippines and Japan and as such its elemental and isotopic content are of interest to the consumers. Its elemental content may reflect the macro nutrient reduction during milling or probable toxic elements uptake. Three Japanese and four Philippine polished rice samples in his study mostly came from rice bought from supermarkets.These rice samples were washed, dried and ground to fine powder. Instrumental neutron activation analysis (INAA), a very sensitive non-destructive multi-element analytical technique, was used for the elemental analysis of the samples and isotope-ratio mass spectrometry (IRMS) was used to obtain the isotopic signatures of the samples. Results show that compared with the unpolished rice standard NIES CRM10b, the polished Japanese and Philippine rice sampled show reduced concentrations of elements by as much as 1/3 to 1/10 of Mg, Mn, K and Na. Levels of Ca and Zn are not greatly affected. Arsenic is found in all the Japanese rice tested at an average concentration of 0.103 μg/g and three out of four of the Philippine rice at an average concentration of 0.070 μg/g. Arsenic contamination may have been introduced from the fertilizer used in rice fields. Higher levels of Br are seen in two of the Philippine rice at 14 and 34 μg/g with the most probable source being the pesticide methyl bromide. Isotopic ratio of ae13C show signature of a C3 plant with possible narrow distinguishable signature of Japanese rice within -27.5 to -28.5 while Philippine rice within -29 to -30. More rice samples will be analyzed to gain better understanding of isotopic signatures to distinguish inter-varietal and/or geographical differences. Elemental composition of soil samples of rice samples sources will be determined for better understanding of uptake mechanisms. (author)

  13. The thermal neutron absorption cross-sections, resonance integrals and resonance parameters of silicon and its stable isotopes

    International Nuclear Information System (INIS)

    The data available up to the end of November 1968 on the thermal neutron absorption cross-sections, resonance absorption integrals, and resonance parameters of silicon and its stable isotopes are collected and discussed. Estimates are given of the mean spacing of the energy levels of the compound nuclei near the neutron binding energy. It is concluded that the thermal neutron absorption cross-section and resonance absorption integral of natural silicon are not well established. The data on these two parameters are somewhat correlated, and three different assessments of the resonance integral are presented which differ over-all by a factor of 230. Many resonances have been detected by charged particle reactions which have not yet been observed in neutron cross-section measurements. One of these resonances of Si28, at En = 4 ± 5 keV might account for the large resonance integral which is derived, very uncertainly, from integral data. The principal source of the measured resonance integral of Si30 has not yet been located. The thermal neutron absorption cross-section of Si28 appears to result mainly from a negative energy resonance, possibly the resonance at En = - 59 ± 5 keV detected by the Si28 (d,p) reaction. (author)

  14. NSDUAZ unfolding package for neutron spectrometry and dosimetry with Bonner spheres

    International Nuclear Information System (INIS)

    NSDUAZ (Neutron Spectrometry and Dosimetry from the Universidad Autónoma de Zacatecas) is a user friendly neutron unfolding package for Bonner sphere spectrometer with 6LiI(Eu) developed under LabView® environment. Unfolding is carried out using a recursive iterative procedure with the SPUNIT algorithm, where the starting spectrum is obtained from a library initial guess spectra to start the iterations. The NSDUAZ performance was evaluated using 252Cf, 252Cf/D2O, 241AmBe neutron sources and the neutrons outside the radial beam port of a TRIGA Mark III nuclear reactor running to 10 W. - Highlights: ► This paper presents the NSDUAZ unfolding package. ► Advantages and drawbacks of NSDUAZ package are pointed out. ► NSDUAZ is evaluated with neutrons from a nuclear reactor and isotopic neutron sources.

  15. New neutron-rich isotopes in the scandium-to-nickel region, produced by fragmentation of a 500 MeV/u 86Kr beam

    International Nuclear Information System (INIS)

    We have measured production cross-sections of the new neutron-rich isotopes 58Ti, 61V, 63Cr, 66Mn, 69Fe, 71Co and neighbouring isotopes that have been identified as projectile fragments from reactions between a 500 MeV/u 86Kr beam and a beryllium target. The isotope identification was performed with the zero-degree magnetic spectrometer FRS at GSI, using in addition time-of-flight and energy-loss mesurements. The experimental production cross-sections for the new nuclides and neighbouring isotopes are compared with an empirical parameterization. The resulting prospects for reaching even more neutron-rich isotopes, such as the doubly-magic nuclide 78Ni, are discussed. (orig.)

  16. Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

    International Nuclear Information System (INIS)

    A large number of new measurements with the activation technique were performed for (n,2n) and neutron-induced ΔZ=1,2 reaction cross sections on the stable molybdenum isotopes in the energy range from 13.5 to 21 MeV. First results were obtained for the 92Mo(n,2n)91Mom,92Mo(n,α)89Zrm,94Mo(n,2n)93Mom,95Mo(n,p)95Nbm,96Mo(n,p) 96Nb,96Mo(n,x)95Nbm, 97Mo(n,p)97Nb, 97Mo(n,p)97Nbm, 97Mo(n,x)96Nb, 98Mo(n,p)98Nbm, 98Mo(n,x)97Nb, 98Mo(n,x)97Nbm, and 100Mo(n,α)97Zr reactions, above 16 MeV. A significant number of high-accuracy 14 MeV measurements were performed which are in good agreement with the measurements above 16 MeV for reactions studied in both energy ranges. The rather complete database for the molybdenum isotopes was analyzed with two different sets of consistent model calculations: a local and a global approach. The global approach (a blind calculation with the TALYS code) provides a good overall description of the dominant reaction channels, although the (n,α) reactions for the heavy isotopes are overpredicted. The local approach (an adjusted calculation with the STAPRE-H code) describes the shapes and magnitudes of the excitation functions well from the reaction thresholds up to 21 MeV using a consistent parameter set, which was optimized based on all experimental information for the nuclei at hand and their immediate neighbors. The agreement between experimental and calculated data is, in general, good both at the maxima and at the tails of the excitation functions, and both for total activation cross sections of a particular channel and for cross sections leading to isomers, showing the viability of the level densities, the optical models, and the γ widths. Comparison of the two model calculations with the data indicates the relevance of an appropriate treatment for preequilibrium (PE) α-particle emission for the description of the data above 14 MeV. Comparison between the model calculations shows largely different PE deuteron emission contributions to the

  17. Study of single particle properties of neutron-rich Na isotopes on the "shore of the island of inversion" by means of neutron-transfer reactions

    CERN Multimedia

    Reiter, P; Blazhev, A A; Riisager, K; Bastin, B; Tengborn, E A; Kruecken, R; Voulot, D; Jeppesen, H B; Hadinia, B; Gernhaeuser, R A; Fynbo, H O U; Georgiev, G P; Habs, D; Fraile prieto, L M; Chapman, R; Nilsson, T; Diriken, J V J; Jenkins, D G; Kroell, T; Leske, J; Huyse, M L; Patronis, N

    We aim at the investigation of single particle properties of neutron-rich Na isotopes around the "shore of the island of inversion". As first experiment of this programme, we propose to study excited states in the isotope $^{29}$Na by a one-neutron transfer reaction with a $^{28}$Na beam at 3 MeV/u obtained from REX-ISOLDE impinging on a CD$_{2}$-target. The $\\gamma$-rays will be detected by the MINIBALL array and the particles by the T-REX array of segmented Si detectors. The main physics aims are to extract from the relative spectroscopic factors information on the configurations contributing to the wave functions of the populated states and, secondly, to identify and characterize negative parity states whose excitation energies reflect directly the N= 28 gap in this region. The results will be compared to recent shell model calculations involving new residual interactions. This will shed new light on the evolution of single particle structure and help to understand the underlying physics relevant for the f...

  18. Study of neutron deficient iridium isotopes by using laser spectroscopy; Etude des noyaux d'iridium deficients en neutrons par spectroscopie laser

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D

    2000-12-19

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes {sup 182-189}Ir, {sup 186}Ir{sup m} and stable isotopes {sup 191,193}Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} ground state and the 5d{sup 7}6s6p {sup 6}F{sub 11/2} excited state. Radioactive iridium isotopes were obtained from {beta}{sup +}/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between {sup 187}Ir and {sup 186}Ir{sup g}, accompanied by a sudden increase in deformation: from {beta}2 {approx} 0,16 to {beta}2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the {pi}3/2{sup +}[402] orbital for the smaller deformations nuclei and with the {pi}1/2{sup -}[541] orbital stemming from the h{sub 9/2} subshell for bigger deformations nuclei. (author)

  19. Determination of isotopic composition of boron in various neutron absorbers by a particle induced gamma-ray emission method

    International Nuclear Information System (INIS)

    A particle induced gamma-ray emission (PIGE) method was utilized for non-destructive determination of isotopic composition of boron (10B/11B atom ratio) in seven natural and two enriched boron based neutron absorber samples. Samples in pellet forms were irradiated with 4 MeV proton beam from FOlded Tandem Ion Accelerator (FOTIA) at BARC, Mumbai. The prompt gamma rays of 429, 718 and 2125 keV from 10B (p, αγ)7Be, 10B(p,p'γ)10B and 11B(p,p' γ)11B, respectively, were measured using high resolution gamma-ray spectrometry. Isotopic composition values were arrived by a relative method using corresponding peak areas of 10B and 11B. (author)

  20. Systematic study of the isotopic dependence of fusion dynamics for neutron- and proton-rich nuclei using a proximity formalism

    CERN Document Server

    Ghodsi, O N; Lari, F

    2016-01-01

    The behaviors of barrier characteristics and fusion cross sections are analyzed by changing neutron over wide range of colliding systems. For this purpose, we have extended our previous study (Eur. Phys. J. A \\textbf{48}, 21 (2012), it is devoted to the colliding systems with neutron-rich nuclei) to 125 isotopic systems with condition of $0.5\\leq N/Z \\leq 1.6$ for their compound nuclei. The AW 95, Bass 80, Denisov DP and Prox. 2010 potentials are used to calculate the nuclear part of interacting potential. The obtained results show that the trend of barrier heights $V_B$ and positions $R_B$ as well as nuclear $V_N$ and Coulomb $V_C$ potentials (at $R=R_B$) as a function of ($N/Z-1$) quantity are non-linear (second-order) whereas the fusion cross sections follow a linear-dependence.

  1. Excited States in 176,178Hg and Shape Coexistence in Very Neutron-Deficient Hg Isotopes

    International Nuclear Information System (INIS)

    Excited states have been observed for the first time in the neutron-deficient 176,178Hg nuclei using the recoil-decay tagging (RDT) technique in which prompt γ rays are associated with a particular isotope through a correlation with the characteristic ground state α decay. Below N=102, the excitation energy of a rotational band built on a prolate shape (β2∼0.25) increases with decreasing mass to the point where there is no longer any evidence for its presence at low spin in 176Hg. The data are in qualitative agreement with recent mean field calculations. copyright 1997 The American Physical Society

  2. Critical survey of beta-decay energies and nuclear masses for the neutron-rich Rb and Cs isotopes

    International Nuclear Information System (INIS)

    Recent experimental results of beta-decay energies for very neutron-rich Rb and Cs isotopes with mass number 94 <= A <= 98 and 142 <= A <= 146, respectively, are presented. From these Qsub(β)-values, mass excesses are derived for the nuclei studied, which are compared with those obtained in direct mass determinations. The advantages and difficulties inherent in both experimental methods are shortly discussed. Finally, the information which can be drawn from a systematic study of beta-decay energies to gain new insight into nuclear structure effects will be mentioned. (orig.)

  3. Fast Neutron Imaging Using 241Am-Be Neutron Source%241Am-Be中子源快中子成像研究

    Institute of Scientific and Technical Information of China (English)

    蒋诗平; 陈亮; 万里飚; 杜淮江; 范扬眉; 韩荣典

    2007-01-01

    中子成像是一种与X射线成像互补的无损探测技术.为探索同位素中子源用于发展可移动的无损检测系统,利用241Am-Be作为中子源,使用自制的中子发光转换屏和X射线胶片作为探测系统开展了快中子成像研究,并获得了较高质量的图像.研究结果表明,利用241Am-Be中子源发展小型探测系统是有潜力的.

  4. Neutron Radiography

    OpenAIRE

    Reddy, A. R.; Rao, M. V. N.

    2012-01-01

    The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  5. Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources

    Science.gov (United States)

    Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

    1972-01-01

    Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

  6. Isotopic distributions of the sup 1 sup 8 N fragmentation products in coincidence with neutrons on targets sup 1 sup 9 sup 7 Au and sup 9 Be

    CERN Document Server

    Li Xiang Qing; Ye Yan Lin; Hua Hui; Chen Tao; Li Zhi Huan; Ge Yuch Eng; Wang Quan Jin; Wu He Yu; Jin Ge; Duan Li Min; Xiao Zhi Gang; Wang Hong Wei; Li Zhu Yu; Wang Su Fang

    2002-01-01

    The authors present the experimental isotopic distributions of the sup 1 sup 8 N projectile fragmentation products Li, Be, B and C in coincidence with neutrons, as well as the inclusive ones on sup 1 sup 9 sup 7 Au and sup 9 Be targets. In the framework of the abrasion-ablation model, these distributions are calculated for various nucleon density distributions of the projectile. The comparison with experimental isotopic distributions of the projectile-like fragments in coincidence with neutrons shows that the information on the nucleon density distribution of the sup 1 sup 8 N projectile can be extracted

  7. Study of shell evolution in the Ni isotopes via one-neutron transfer reaction in $^{70}$Ni

    CERN Multimedia

    This proposal aims at the study of the single particle properties of the neutron-rich nickel isotopes, specifically of the $^{71}$Ni isotope via a $^{70}$Ni(d,p) $^{71}$Ni reaction. The $^{70}$Ni beam will be delivered by HIE-ISOLDE at 5.5 MeV/u onto a 1.0 mg/cm$^{2}$ CD$_{2}$ target. The protons produced in the (d,p) reaction will be detected with the T-REX silicon array either in singles or in coincidence with $\\gamma$- rays recorded by MINIBALL. The experimental results will be compared with large-scale shell-model calculations using effective interactions that involve large valence spaces for protons and neutrons, with excitations beyond the Z =28 and N=50 shell gap. This comparison will permit the study of the single-particle orbital d$_{5/2}$ that together with the quasi-SU3 partner g$_{9/2}$ gives rise to the collectivity in this region and has direct implications on the $^{78}$Ni.

  8. Cumulative fission yields of short-lived isotopes under natural-abundance-boron-carbide-moderated neutron spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce; Wittman, Richard S.; Friese, Judah I.; Kephart, Rosara F.

    2015-04-09

    The availability of gamma spectroscopy data on samples containing mixed fission products at short times after irradiation is limited. Due to this limitation, data interpretation methods for gamma spectra of mixed fission product samples, where the individual fission products have not been chemically isolated from interferences, are not well-developed. The limitation is particularly pronounced for fast pooled neutron spectra because of the lack of available fast reactors in the United States. Samples containing the actinide isotopes 233, 235, 238U, 237Np, and 239Pu individually were subjected to a 2$ pulse in the Washington State University 1 MW TRIGA reactor. To achieve a fission-energy neutron spectrum, the spectrum was tailored using a natural abundance boron carbide capsule to absorb neutrons in the thermal and epithermal region of the spectrum. Our tailored neutron spectrum is unique to the WSU reactor facility, consisting of a soft fission spectrum that contains some measurable flux in the resonance region. This results in a neutron spectrum at greater than 0.1 keV with an average energy of 70 keV, similar to fast reactor spectra and approaching that of 235U fission. Unique fission product gamma spectra were collected from 4 minutes to 1 week after fission using single-crystal high purity germanium detectors. Cumulative fission product yields measured in the current work generally agree with published fast pooled fission product yield values from ENDF/B-VII, though a bias was noted for 239Pu. The present work contributes to the compilation of energy-resolved fission product yield nuclear data for nuclear forensic purposes.

  9. Radionuclides induced by environmental neutrons. Discovery of natural radioactive Eu and Co isotopes and their contribution to the evaluation of Atomic-bombing neutrons in Hiroshima and Nagasaki

    Energy Technology Data Exchange (ETDEWEB)

    Komura, Kazuhisa [Kanazawa Univ., Low Level Radioactivity Lab., Tatsunokuchi, Ishikawa (Japan); Yousef, Ahmed M. [South Valley Univ. (Egypt)

    2001-06-01

    Radioactive europium and cobalt isotopes induced by environmental neutrons have been discovered by low-background Ge detector installed in Ogoya underground laboratory. Specific activities of {sup 152}Eu, {sup 154}Eu and {sup 155}Eu and {sup 60}Co were measured for recent and old europium and cobalt reagents. Observed activities are 0.06-0.52 dpm g{sup -1} for {sup 152}Eu, 0.09-0.16 dpm g{sup -1} for {sup 154}Eu and 0.005-0.16 dpm g{sup -1} for {sup 155}Eu and 0.007-0.083 dpm g{sup -1} for {sup 60}Co. Contribution of natural {sup 152}Eu and {sup 60}Co in Atomic-bomb exposed samples are found to be negligible low and less than 10%, respectively. (author)

  10. Radionuclides induced by environmental neutrons. Discovery of natural radioactive Eu and Co isotopes and their contribution to the evaluation of Atomic-bombing neutrons in Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Radioactive europium and cobalt isotopes induced by environmental neutrons have been discovered by low-background Ge detector installed in Ogoya underground laboratory. Specific activities of 152Eu, 154Eu and 155Eu and 60Co were measured for recent and old europium and cobalt reagents. Observed activities are 0.06-0.52 dpm g-1 for 152Eu, 0.09-0.16 dpm g-1 for 154Eu and 0.005-0.16 dpm g-1 for 155Eu and 0.007-0.083 dpm g-1 for 60Co. Contribution of natural 152Eu and 60Co in Atomic-bomb exposed samples are found to be negligible low and less than 10%, respectively. (author)

  11. Calculation and analysis of neutron and radiation characteristics of lead coolants with isotopic tailoring for future nuclear power facilities

    Energy Technology Data Exchange (ETDEWEB)

    Blokhin, A.I.; Ivanov, A.P.; Korobeinikov, V.V.; Lunev, V.P.; Manokhin, V.N.; Khorasanov, G.L. [SSC RF A. I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Kaluga Region (Russian Federation)

    2000-03-01

    A new type of safe fast reactor with lead coolant was proposed in Russia. The use of coolants with low moderating properties is one of the ways to get a hard neutron spectrum and an increase in the burning of Np-237, Am-243 and other miner actinides(MA) fissionable preferentially in the fast reactor. The stable lead isotope, Pb-208, is proposed as the one of such coolants. The neutron inelastic scattering cross-section of Pb-208 is 3.0-3.5 times less than the one of other lead isotopes. Calculation of the MA transmutation rates in the standard BN-type fast reactor with different coolants is performed by Monte-Carlo method using Code MMKFK. Six various models are simulated for the fast reactor blanket with different kinds of fuel and coolant. The fast reactor with natural-lead coolant practically does not differ from the reactor with sodium coolant relative to MA incineration. The use of Pb-208 as a coolant in the fast reactor results in increasing incineration of MA from 18 to 26% in comparison with a usual fast reactor. Calculation of induced radioactivity was performed using the FISPACT-3 inventory code, also. The results include total induced radioactivity and dose rate for initial material composition and selected long-lived radionuclides. The calculations show that the coolant consisting of lead isotope, Pb-206, or Pb-207, can be considered as the low-activation one because it does not practically contain long-lived toxic radionuclides. (M. Suetake)

  12. Spins, charge radii and magnetic moments of neutron-rich Mn isotopes measured with bunched beam Collinear Laser Spectroscopy

    CERN Document Server

    AUTHOR|(CDS)2085887; Heylen, Hanne

    In this work, the odd-even $^{51–63}$Mn isotopes have been analyzed using collinear laser spectroscopy, from which the magnetic dipole moment and the change in change in mean square charge radius can be determined. The magnetic moment is very sensitive to the composition of the total nuclear wave function, while the charge radius gives information about the relative size and degree of deformation of the nucleus. An additional advantage of collinear laser spectroscopy is the possibility of direct measurement of the nuclear spin. The main motivation behind the study of these isotopes is to investigate the change in nuclear structure when approaching neutron number N = 40. This region is of interest due to the apparent doubly magic nature of $^{68}$Ni , which is not seen in the N = 40 isotopes of $^{26}$Fe and $^{24}$Cr. Mn, situated between these elements, offers another perspective due to its uncoupled proton. Based on the observed spectra and extracted moments, spins were assigned to $^{59,61,63}$Mn. The ex...

  13. Neutron and proton shell closure in the superheavy region via cluster radioactivity in 280−314 116 isotopes

    Indian Academy of Sciences (India)

    K P Santhosh; R K Biju

    2009-04-01

    Based on the concept of cold valley in fission and fusion, the radioactive decay of superheavy280−314116 nuclei was studied taking Coulomb and proximity potentials as the interacting barrier. It is found that the inclusion of proximity potential does not change the position of minima but minima become deeper which agrees with the earlier findings of Gupta and co-workers. In addition to alpha particle minima, the other deepest minima occur for 8Be, 12,14C clusters. In the fission region two deep regions are found each consisting of several comparable minima, the first region centred on 208Pb and the second is around 132Sn. The cluster decay half-lives and other characteristics are computed for various clusters ranging from alpha particle to 70Ni. The computed half-lives for alpha decay match with the experimental values and with the values calculated using Viola–Seaborg–Sobiczewski (VSS) systematic. The plots connecting computed values and half-lives against neutron number of daughter nuclei were studied for different clusters and it is found that the next neutron shell closures occur at = 162, 172 and 184. Isotopic and isobaric mass parabolas are studied for various cluster emissions and minima of parabola indicate neutron shell closure at = 162, 184 and proton shell closure at = 114. Our study shows that $^{276}_{162}$114 is the deformed doubly magic and $^{298}_{184}$114 is the spherical doubly magic nuclei.

  14. Single-neutron orbits near {sup 78}Ni: Spectroscopy of the N=49 isotope {sup 79}Zn

    Energy Technology Data Exchange (ETDEWEB)

    Orlandi, R., E-mail: orlandi.riccardo@jaea.go.jp [Instituto de Estructura de la Materia, IEM-CSIC, Madrid, E-28006 (Spain); KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Heverlee (Belgium); School of Engineering, University of the West of Scotland, Paisley, PA1 2BE (United Kingdom); Scottish Universities Physics Alliance (SUPA) (United Kingdom); Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195 (Japan); Mücher, D. [Physik Department E12, Technische Universität München, D-85748 Garching (Germany); Raabe, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Heverlee (Belgium); Jungclaus, A. [Instituto de Estructura de la Materia, IEM-CSIC, Madrid, E-28006 (Spain); Pain, S.D. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bildstein, V. [Physik Department E12, Technische Universität München, D-85748 Garching (Germany); Chapman, R. [School of Engineering, University of the West of Scotland, Paisley, PA1 2BE (United Kingdom); Scottish Universities Physics Alliance (SUPA) (United Kingdom); Angelis, G. de [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, I-35020 (Italy); Johansen, J.G. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus (Denmark); Van Duppen, P. [KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Heverlee (Belgium); Andreyev, A.N. [School of Engineering, University of the West of Scotland, Paisley, PA1 2BE (United Kingdom); Scottish Universities Physics Alliance (SUPA) (United Kingdom); Department of Physics, University of York, Heslington, YO10 5DD (United Kingdom); Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195 (Japan); and others

    2015-01-05

    Single-neutron states in the Z=30, N=49 isotope {sup 79}Zn have been populated using the {sup 78}Zn(d, p){sup 79}Zn transfer reaction at REX-ISOLDE, CERN. The experimental setup allowed the combined detection of protons ejected in the reaction, and of γ rays emitted by {sup 79}Zn. The analysis reveals that the lowest excited states populated in the reaction lie at approximately 1 MeV of excitation, and involve neutron orbits above the N=50 shell gap. From the analysis of γ-ray data and of proton angular distributions, characteristic of the amount of angular momentum transferred, a 5/2{sup +} configuration was assigned to a state at 983 keV. Comparison with large-scale-shell-model calculations supports a robust neutron N=50 shell-closure for {sup 78}Ni. These data constitute an important step towards the understanding of the magicity of {sup 78}Ni and of the structure of nuclei in the region.

  15. Production of neutron-rich copper isotopes in 30-MeV proton-induced fission of sup 2 sup 3 sup 8 U

    CERN Document Server

    Kruglov, K; Bruyneel, B; Dean, S S; Franchoo, S; Huyse, M; Kudryavtsev, Y; Müller, W F; Prasad, N V S; Raabe, R; Reusen, I; Schmidt, K H; Van De Vel, K; Van Duppen, P; Van Roosbroeck, J; Weissman, L

    2002-01-01

    The neutron-rich isotopes sup 7 sup 0 sup - sup 7 sup 6 Cu have been produced in 30-MeV proton-induced fission of sup 2 sup 3 sup 8 U using the Ion Guide Laser Ion Source (IGLIS) at LISOL. The production rates of the copper isotopes, and of the nickel and cobalt isotopes that were measured earlier, are compared to cross section calculations. Based on these new results an estimate for the cross section of sup 7 sup 8 Ni is given.

  16. Dynamical simulation of neutron-induced fission of uranium isotopes using four-dimensional Langevin equations

    Science.gov (United States)

    Pahlavani, M. R.; Mirfathi, S. M.

    2016-04-01

    Four-dimensional Langevin equations have been suggested for the dynamical simulation of neutron-induced fission at low and medium excitation energies. The mass distribution of the fission fragments, the neutron multiplicity, and the fission cross section for the thermal and fast neutron-induced fission of 233U, 235U, and 238U is studied by considering energy dissipation of the compound nucleus through the fission using four-dimensional Langevin equations combined with a Monte Carlo simulation approach. The calculated results using this approach indicate reasonable agreement with available experimental data.

  17. Discovery and cross-section measurement of neutron-rich isotopes in the element range from neodymium to platinum with the FRS

    International Nuclear Information System (INIS)

    Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of 60⩽Z⩽78. The new isotopes were unambiguously identified in reactions with a 238U beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium.

  18. Elastic and inelastic scattering of fast neutrons from the even isotopes of Se

    International Nuclear Information System (INIS)

    The differential cross sections for elastic and inelastic scattering of neutrons by 76Se, 78Se, 80Se and 82Se have been measured at 8-MeV incident neutron energy, and by 76Se and 82Se at 6- and 10-MeV incident energies. The differences observed in the elastic scattering cross sections are interpreted as an effect of the isospin term in the scattering potential. A detailed analysis of the elastic scattering data is presented

  19. Neutron total and scattering cross sections of some even isotopes of molybdenum and the optical model

    International Nuclear Information System (INIS)

    Neutron total and elastic and inelastic scattering cross sections of 92Mo, 96Mo, 98Mo and 100Mo were measured. Neutron total cross sections were determined at intervals of less than or equal to 10 keV from 1.6 to 5.5 MeV with resolutions of approximately 10 keV. Neutron elastic and inelastic scattering cross sections were measured from 1.8 to 4.0 MeV at intervals of 0.2 MeV. Neutron groups corresponding to the excitation of forty states were identified. The experimental results were examined in the context of optical- and statistical-nuclear models. It was concluded that the real part of the optical potential includes a term proportional to [(N - Z)/A] and suggested that the imaginary part is shell dependent with decreasing magnitude as N = 50 is approached. Comparison of measured and calculated inelastic neutron excitation cross sections suggested a number of J/sup π/ assignments extending previous knowledge. The experimental and calculational results were used, together with previously reported values, to generate an evaluated neutron total and scattering cross section file in the ENDF format extending over the energy range 0.1 to 8.0 MeV

  20. Neutron dosimetry

    International Nuclear Information System (INIS)

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq 241 Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s-1 and 0,5 μSv s-1. A calibrated 50 nSv s-1 thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the 241 Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold 241 Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,α) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kVpp cm-1, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46± 0,09) 104 tracks cm-2 mSv-1 for thermal neutrons, (9±3) 102 tracks cm-2 mSV-1 for intermediate neutrons and (26±4) tracks cm-2 mSv-1 for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990's ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is sufficiently sensitive to thermal and intermediate neutrons but fast neutron monitoring ar radiological protection level

  1. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  2. Search for halo nucleus in Mg isotopes through the measurements of reaction cross sections towards the vicinity of neutron drip line

    Directory of Open Access Journals (Sweden)

    Takechi M.

    2014-03-01

    Full Text Available Reaction cross sections (σR for 24–38Mg on C targets at the energies of around 240 MeV/nucleon have been measured precisely at RIBF, RIKEN for the purpose of obtaining the crucial information on the changes of nuclear structure in unstable nuclei, especially around the so-called “island of inversion” region. In the island of inversion region, which includes neutron-rich Ne, Na, and Mg isotopes, the vanishing of the N = 20 magic number for neutrons have been discussed along with nuclear deformation. The present result suggest deformation features of Mg isotopes and shows a large cross section of weakly-bound nucleus 37Mg, which could be caused by a neutron halo formation.

  3. Search for halo nucleus in Mg isotopes through the measurements of reaction cross sections towards the vicinity of neutron drip line

    International Nuclear Information System (INIS)

    Reaction cross sections (σR) for 24-38Mg on C targets at the energies of around 240 MeV/nucleon have been measured precisely at RIBF, RIKEN for the purpose of obtaining the crucial information on the changes of nuclear structure in unstable nuclei, especially around the so-called 'island of inversion' region. In the island of inversion region, which includes neutron-rich Ne, Na, and Mg isotopes, the vanishing of the N=20 magic number for neutrons have been discussed along with nuclear deformation. The present result suggests deformation features of Mg isotopes and shows a large cross section of weakly-bound nucleus 37Mg, which could be caused by a neutron halo formation. (authors)

  4. Competing γ-rigid and γ-stable vibrations in neutron-rich Gd and Dy isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Budaca, R.; Budaca, A.I. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

    2015-10-15

    An exactly separable version of the Bohr Hamiltonian which combines the γ-stable and γ-rigid axial vibration-rotation is used to describe the collective properties of few neutron-rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape phase space. While the γ-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff γ oscillation hypothesis, the β vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables. (orig.)

  5. Competing γ-rigid and γ-stable vibrations in neutron-rich Gd and Dy isotopes

    International Nuclear Information System (INIS)

    An exactly separable version of the Bohr Hamiltonian which combines the γ-stable and γ-rigid axial vibration-rotation is used to describe the collective properties of few neutron-rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape phase space. While the γ-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff γ oscillation hypothesis, the β vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables. (orig.)

  6. Experiments to produce odd-mass neutron-deficient isotopes of superheavy elements by 48Ca ion-induced reactions

    International Nuclear Information System (INIS)

    Experimentals to produce neutron-deficient isotopes of superhevy elements in the reactions 233U (48Ca, 2n)279112, sup(231)Pa(48Ca, 3n)sup(276)111 and sup(232)Th(48Ca,2-3n)sup(277-276)110 have been carried out using a heavy ion beam of the U-300 accelerator. In these reactions, the upper limits of production cross sections and spontaneous-fission half-lives been determined to be 7x10-35 cm2, 5x10-35 cm2 and 2x10-35 cm2, and 0.05 s, 0.003 s and 0.003 s, respectively

  7. Impact of triaxiality on the rotational structure of neutron-rich rhenium isotopes

    Directory of Open Access Journals (Sweden)

    M.W. Reed

    2016-01-01

    Full Text Available A number of 3-quasiparticle isomers have been found and characterised in the odd-mass, neutron-rich, 187Re, 189Re and 191Re nuclei, the latter being four neutrons beyond stability. The decay of the isomers populates states in the rotational bands built upon the 9/2−[514] Nilsson orbital. These bands exhibit a degree of signature splitting that increases with neutron number. This splitting taken together with measurements of the M1/E2 mixing ratios and with the changes observed in the energy of the gamma-vibrational band coupled to the 9/2−[514] state, suggests an increase in triaxiality, with γ values of 5°, 18° and 25° deduced in the framework of a particle-rotor model.

  8. Microscopic description of fission in neutron-rich plutonium isotopes with the Gogny-D1M energy density functional

    International Nuclear Information System (INIS)

    The most recent parametrization D1M of the Gogny energy density functional is used to describe fission in the isotopes 232-280Pu. We resort to the methodology introduced in our previous studies (Phys. Rev. C 88, 054325 (2013) and Phys. Rev. C 89, 054310 (2014)) to compute the fission paths, collective masses and zero point quantum corrections within the Hartree-Fock-Bogoliubov framework. The systematics of the spontaneous fission half-lives tSF, masses and charges of the fragments in plutonium isotopes is analyzed and compared with available experimental data. We also pay attention to isomeric states, the deformation properties of the fragments as well as to the competition between the spontaneous fission and α-decay modes. The impact of pairing correlations on the predicted tSF values is demonstrated with the help of calculations for 232-280Pu, in which the pairing strengths of the Gogny-D1M energy density functional are modified by 5% and 10%, respectively. We further validate the use of the D1M parametrization through the discussion of the half-lives in 242-262Fm. Our calculations corroborate that, though the uncertainties in the absolute values of physical observables are large, the Gogny-D1M Hartree-Fock-Bogoliubov framework still reproduces the trends with mass and/or neutron numbers and therefore represents a reasonable starting point to describe fission in heavy nuclear systems from a microscopic point of view. (orig.)

  9. Nuclear charge radii snf moments of neutron deficient Ba isotopes from high resolution laser spectroscopy

    International Nuclear Information System (INIS)

    The hyperfine structure of the Ba resonance line at lambda = 553,5 nm was measured by dye laser induced resonance fluorescence on an atomic beam for 15 isotopes and isomers with atomic numbers between 126 and 138. The results have been used to deduce differences of rms charge radii, magnetic dipole and electric quadrupole moments. (orig./AH)

  10. Self-consistent calculations of the strength function and radiative neutron capture cross section for stable and unstable tin isotopes

    CERN Document Server

    Goriely, S; Krewald, S

    2011-01-01

    The E1 strength function for 15 stable and unstable Sn even-even isotopes from A=100 till A=176 are calculated using the self-consistent microscopic theory which, in addition to the standard (Q)RPA approach, takes into account the single-particle continuum and the phonon coupling. Our analysis shows two distinct regions for which the integral characteristics of both the giant and pygmy resonances behave rather differently. For neutron-rich nuclei, starting from $^{132}$Sn, we obtain a giant E1 resonance which significantly deviates from the widely-used systematics extrapolated from experimental data in the $\\beta$-stability valley. We show that the inclusion of the phonon coupling is necessary for a proper description of the low-energy pygmy resonances and the corresponding transition densities for $A132$ region the influence of phonon coupling is significantly smaller. The radiative neutron capture cross sections leading to the stable $^{124}$Sn and unstable $^{132}$Sn and $^{150}$Sn nuclei are calculated wi...

  11. Inverse-kinematics one-neutron pickup with fast rare-isotope beams

    International Nuclear Information System (INIS)

    Measurements and reaction model calculations are reported for single-neutron pickup reactions onto a fast 22Mg secondary beam at 84 MeV per nucleon. Measurements made on both carbon and beryllium targets, having very different structures, were used to investigate the likely nature of the pickup reaction mechanism. The measurements involve thick reaction targets and γ-ray spectroscopy of the projectile-like reaction residue for final-state resolution, which permit experiments with low incident beam rates compared to traditional low-energy transfer reactions. From measured longitudinal momentum distributions we show that the 12C(22Mg,23Mg+γ)X reaction largely proceeds as a direct two-body reaction, with the neutron transfer producing bound 11C target residues. The corresponding reaction on the 9Be target seems to largely leave the 8Be residual nucleus unbound at excitation energies high in the continuum. We discuss the possible use of such fast-beam one-neutron pickup reactions to track single-particle strength in exotic nuclei and also their expected sensitivity to neutron high-l (intruder) states, which are often direct indicators of shell evolution and the disappearance of magic numbers in the exotic regime.

  12. A new pulsed release method for element selective production of neutron rich isotopes near 208Pb

    International Nuclear Information System (INIS)

    A new method to reduce the isobaric contamination problem for the production of neutron rich Bi, Pb and Tl nuclei at on-line mass separators, based on the pulsed release of these radioactive species, is presented. The results of a feasibility study are reported. (orig.)

  13. Examination of different strengths of octupole correlations in neutron-rich Pr and Pm isotopes

    Czech Academy of Sciences Publication Activity Database

    Thiamova, G.; Alexa, P.; Hons, Zdeněk; Simpson, G.S.

    2012-01-01

    Roč. 86, č. 4 (2012), 044334/1-044334/5. ISSN 0556-2813 R&D Projects: GA ČR GAP203/10/0310 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * octupole correlations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.715, year: 2012

  14. Measurements of fast neutron capture and fission cross sections of minor actinide isotopes

    International Nuclear Information System (INIS)

    The neutron capture cross sections of 240Pu, 242Pu and 241Am were measured in the energy range from 10 to 250 keV, with 197Au and 238U as standards. The subthreshold fission cross sections of 240Pu and 241Am were determined relative to 235U in the energy range from 10 to 250 keV and 10 keV to 1 MeV, respectively. Continuous neutron spectra and in one case monoenergetic neutrons were produced by means of the Li(p,n) and T(p,n) reactions with the Karlsruhe 3-MV pulsed Van de Graaff accelerator. Capture events were detected by a Moxon Rae detector, and fission events, observed with a NE213 liquid scintillator. The high neutron flux available at flight paths as short as 50 to 135 mm allowed a statistical accuracy of 1 to 3% for most of the measured data together with a moderate energy resolution of 10 to 30 ns/m. An overall uncertainty between 5 and 10% was obtained in most of the measurements. A comparison is made to recent data of other authors and to evaluated files. 8 figures, 1 table

  15. Neutron separation energies of Ca, Sn and Pb isotopes using different mass models

    International Nuclear Information System (INIS)

    In this work we present an investigation of S2n which is quite a sensitive quantity to test any microscopic model. Two popular models are Relativistic Mean Field (RMF) and Infinite Nuclear Matter (INM) model. The objective of the present study is to undertake a systematic analysis of two neutron separation energy using these models in comparison with experiment

  16. Neutron cross section evaluations of europium isotopes in 1 keV - 30 MeV energy range. Format - validation - comparison; Evaluation de sections efficaces pour des neutrons incidents sur des isotopes d'europium aux energies 1 keV - 30 MeV. Format - validation - comparaison

    Energy Technology Data Exchange (ETDEWEB)

    Dossantos-Uzarralde, P.; Le Luel, C.; Bauge, E. [CEA Bruyeres le Chatel, 91 (France). Dept. de Physique Theorique et Appliquee

    2004-07-01

    This paper presents neutron cross section evaluations of Europium isotopes. The cross sections are evaluated in 1 keV - 30 MeV energy range for the isotopes {sup 146}Eu, {sup 147}Eu, {sup 148}Eu, {sup 149}Eu, {sup 150}Eu, {sup 151}Eu, {sup 152}Eu, {sup 153}Eu, {sup 154}Eu in their ground state. This evaluation includes cross section productions of the long life isomeric states. Special attention is put on the options used for the description of the files written in ENDF-6 format. The final issue is a proposal of a new breed of ENDF-6 formatted neutron activation file. (authors)

  17. Neutron interactions with segmented germanium detectors studies with a GERDA Phase II prototype detector

    International Nuclear Information System (INIS)

    The GERmanium Detector Array, GERDA, is designed to search for ''neutrinoless double beta decay'' (0ν2β) with Germanium detectors enriched in 76Ge. The estimate of neutron induced background relies purely on Geant4 simulations. In order to study neutron interactions with the Germanium itself as well as the surrounding materials, a prototype detector for GERDA Phase II with 18 segments was exposed to an AmBe neutron source. The simulated results from the Geant4-based MaGe MC package agree in general with the measurements, thus verifying the MC used. The Geant4 package is able to simulate most de-excitation photons from the Germanium isotopes and the nuclei recoil process after interacting with neutrons. However, some physics processes are missing in the simulation. (orig.)

  18. An evaluation method of the neutron fluence and spectrum by measuring the change of isotopic abundance ratios of arbitrary pairs of nuclides on heavy irradiation

    International Nuclear Information System (INIS)

    An evaluation method of the neutron fluence and mean spectrum with which samples have been irradiated is proposed. The principle is based on measuring the change of the isotopic abundance ratios of arbitrary pairs of nuclides having different neutron absorption cross sections for both thermal and intermediate neutrons. Advantages of the method are as follows, although sensitivity is lower than that of the ordinary activation method in a short irradiation period. i) Any sample can be used irrespective of irradiation history. ii) Nuclides present as impurities in samples can be used as detectors. iii) Neutron fluences and mean spectra with which samples have been heavily irradiated can be measured with reasonable accuracy, thus making it possible to offer the direct information to radiation damage studies. The present study deals with the principle and applicability of the method. (author)

  19. Onset of collectivity in neutron-rich Sr and Kr isotopes: Prompt spectroscopy after Coulomb excitation at REX-ISOLDE, CERN

    Directory of Open Access Journals (Sweden)

    Clément E.

    2013-12-01

    Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  20. Yield estimation of neutron-rich rare isotopes induced by 200 MeV/u {sup 132}Sn beams by using GEANT4

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae Won [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Min, Kyung Joo; Ham, Cheolmin [Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Tae-Sun [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Hong, Seung-Woo, E-mail: swhong@skku.ac.kr [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-04-15

    A so-called “two-step reaction scheme”, in which neutron-rich rare isotopes obtained from ISOL are post-accelerated and bombarded on a second target, is employed to estimate the production yields of exotic rare isotopes. The production yields of neutron-rich rare isotope fragments induced by 200 MeV/u {sup 132}Sn beams bombarded on a {sup 9}Be target are estimated with Monte Carlo code, GEANT4. To substantiate the use of GEANT4 for this study, benchmark calculations are done for 80 MeV/u {sup 59}Co, 95 MeV/u {sup 72}Zn, 500 MeV/u {sup 92}Mo, and 950 MeV/u {sup 132}Sn beams on the {sup 9}Be target. It is found that {sup 132}Sn beams can produce neutron-rich rare isotopes with 45 ⩽ Z ⩽ 50 more effectively than {sup 238}U beams at the same energy per nucleon.

  1. Shape coexistence in neutron-deficient mercury isotopes: 187-188Hg

    International Nuclear Information System (INIS)

    The high-spin states of the 187-188Hg isotopes have been investigated via the 164 Dy(28Si,xn) reactions by means of in-beam gamma-ray spectroscopy using the multidetector 4π-array ''Chateau de Cristal'' at the Strasbourg CRN laboratory. The level scheme have been established up to spin 45/2 in 187Hg and 24 in 188Hg. The various band structures are interpreted within the framework of the cranked shell model. For the first time in an odd-A mercury isotope, a prolate structure is found starting at very low energy and coexisting with the oblate structure based on the 13/2+ isomer. The hypothesis of a superdeformed structure in 188Hg in addition to the already known oblate and prolate shapes is conjectured

  2. Neutron-rich isotope production using a uranium carbide - carbon nanotubes SPES target prototype

    Energy Technology Data Exchange (ETDEWEB)

    Corradetti, S. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Universita di Padova, Dipartimento di Scienze Chimiche, Padova (Italy); Biasetto, L. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Universita di Padova, Dipartimento di Tecnica e Gestione dei Sistemi Industriali, Vicenza (Italy); Manzolaro, M.; Scarpa, D.; Andrighetto, A.; Prete, G. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Carturan, S. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Vasquez, J. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Universita di Padova, Dipartimento di Ingegneria dell' Informazione, Padova (Italy); Zanonato, P. [Universita di Padova, Dipartimento di Scienze Chimiche, Padova (Italy); Colombo, P. [Universita di Padova, Dipartimento di Ingegneria Industriale, Padova (Italy); Jost, C.U. [University of Tennessee, Department of Physics and Astronomy, Knoxville (United States); Stracener, D.W. [Oak Ridge National Laboratory, Physics Division, Oak Ridge (United States)

    2013-05-15

    The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community. (orig.)

  3. Neutron-Rich Isotope Production Using a Uranium Carbide Carbon Nanotubes SPES Target Prototype

    Energy Technology Data Exchange (ETDEWEB)

    Corradetti, Stefano [ORNL; Biasetto, Lisa [INFN, Laboratori Nazionali di Legnaro, Italy; Manzolaro, Mattia [INFN, Laboratori Nazionali di Legnaro, Italy; Scarpa, Daniele [ORNL; Carturan, S. [INFN, Laboratori Nazionali di Legnaro, Italy; Andrighetto, Alberto [INFN, Laboratori Nazionali di Legnaro, Italy; Prete, Gianfranco [ORNL; Vasquez, Jose L [ORNL; Zanonato, P. [Dipartimento di Scienze Chimiche, Padova, Italy; Colombo, P. [Dipartimento di Ingegneria Meccanica, Padova, Italy; Jost, Carola [University of Tennessee, Knoxville (UTK); Stracener, Daniel W [ORNL

    2013-01-01

    The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community.

  4. Radiochemical search for neutron-rich isotopes of nielsbohrium in the (16)O + (254)Es reaction

    International Nuclear Information System (INIS)

    We have used on-line gas chromatography to search for new isotopes of element 107 near the deformed sub-shell at N = 162 and Z = 108. Enhanced nuclear stability is predicted for this region. 254gEs was irradiated with 16O at barrier energies to minimize the fusion hindrance in the entrance channel and to reduce the excitation energy of the compound nucleus to a minimum value. For half-lives between roughly two seconds and two minutes no signal for a positive identification of a new isotope of element 107 was detected. Consequently, only an upper cross-section limit of a few nanobarns was obtained. While this cross-section limit was too high to probe the influence of the predicted enhanced nuclear ground-state stability on the survival probability in the fission/evaporation competition, a very large cross-section enhancement would have been detectable. (orig.)

  5. Neutron-rich isotope production using a uranium carbide - carbon nanotubes SPES target prototype

    Science.gov (United States)

    Corradetti, S.; Biasetto, L.; Manzolaro, M.; Scarpa, D.; Carturan, S.; Andrighetto, A.; Prete, G.; Vasquez, J.; Zanonato, P.; Colombo, P.; Jost, C. U.; Stracener, D. W.

    2013-05-01

    The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community.

  6. Neutron-rich isotope production using a uranium carbide - carbon nanotubes SPES target prototype

    International Nuclear Information System (INIS)

    The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community. (orig.)

  7. Penning trap mass spectrometry of neutron-deficient Rb- and Sr-isotopes

    International Nuclear Information System (INIS)

    We present a mass spectrometer for radioactive nuclei. The principle of measurement is the confinement of the ions in a penning trap and the subsequent determination of their cyclotron frequency νc which is inversely proportional to the mass. The resolution of the method is approximately 106, the achieved accuracy in mass determination 10-7. We present some results from our survey of light Rb- and Sr-isotopes. 3 figs., 8 refs. (author)

  8. $\\beta$-decay study of neutron-rich Tl and Pb isotopes

    CERN Multimedia

    It is proposed to study the structure of neutron-rich nuclei beyond $^{208}$Pb. The one-proton hole $^{211-215}$Tl and the semi magic $^{213}$Pb will be produced and studied via nuclear and atomic spectroscopy searching for long-lived isomers and investigating the $\\beta$-delayed $\\gamma$- emission to build level schemes. Information on the single particle structure in $^{211-215}$Pb, especially the position of the g$_{9/2}$ and i$_{11/2}$ neutron orbitals, will be extracted along with lifetimes. The $\\beta$-decay will be complemented with the higher spin selectivity that can be obtained by resonant laser ionization to single-out the decay properties of long-living isomers in $^{211,213}$Tl and $^{213}$Pb.

  9. Evidence for a smooth onset of deformation in the neutron-rich Kr isotopes

    CERN Document Server

    Albers, M; Nomura, K; Blazhev, A; Jolie, J; Mucher, D; Bastin, B; Bauer, C; Bernards, C; Bettermann, L; Bildstein, V; Butterworth, J; Cappellazzo, M; Cederkall, J; Cline, D; Darby, I; Das Gupta, S; Daugas, J M; Davinson, T; De Witte, H; Diriken, J; Filipescu, D; Fiori, E; Fransen, C; Gaffney, L P; Georgiev, G; Gernhauser, R; Hackstein, M; Heinze, S; Hess, H; Huyse, M; Jenkins, D; Konki, J; Kowalczyk, M; Kroll, T; Krucken, R; Litzinger, J; Lutter, R; Marginean, N; Mihai, C; Moschner, K; Napiorkowski, P; Nara Singh, B S; Nowak, K; Otsuka, T; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Rigby, S; Robledo, L M; Rodriguez-Guzman, R; Rudigier, M; Sarriguren, P; Scheck, M; Seidlitz, M; Siebeck, B; Simpson, G; Thole, P; Thomas, T; Van de Walle, J; Van Duppen, P; Vermeulen, M; Voulot, D; Wadsworth, R; Wenander, F; Wimmer, K; Zell, K O; Zielinska, M

    2012-01-01

    The neutron-rich nuclei $^{94,96}$Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2$^{+}$ states and their absolute $E2$ transition strengths to the ground state are determined and discussed in the context of the $E(2^{+}_{1})$ and $B(E2;2^{+}_{1} \\rightarrow 0^{+}_{1})$ systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.

  10. Activation analysis of pit-coal ash content with the use of isotopic fast neutron source

    International Nuclear Information System (INIS)

    The neutron activation techniques of coal ash determination are briefly reviewed and a new version of activation analysis using fast neutrons from 239Pu-Be source and basing on the reactions 28Si(n,p)28Al and 27Al(n,p)27Mg is proposed. 72 samples of pit-coals with ash content ranging from 3 to 40% were measured. The linear calibration function between ash content and both, 1.78 MeV and 0.84 MeV, γ-ray counts was obtained. The precision (0.94% ash for 17% ash content) and accuracy (1.4%ash for the whole range) were evaluated. Comparison of the results with those of fluorescent-scattering methods is made. (author)

  11. Identification of neutron-rich new isotopes and their half-lives

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Kotoyuki; Taniguchi, Akihiro [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.

    1996-03-01

    Recently, some new isotopes such as {sup 156}Pm, {sup 155}Nd, {sup 154}Pr, {sup 152}Ce were identified using on-line isotope separation apparatus (KUR-ISOL). The half-lives of these isotopes were several seconds and those of other unknown nuclides are assumed to be around one second or extremely shorter. Detections of {sup 150}La, {sup 153}Ce, {sup 157}Nd etc. have not been succeeded by previous studies. In order to raise the efficiency for identification of short-lived nuclides, it seems essential to remarkably increase the beam strength of KUR-ISOL and to secure its safety operating. A mixed-gas jet method has been developed using a mixed gas of N{sub 2} and He and the beam strength increased by more than one digit. In addition, the exchange over time for gas was shortened by increasing the gas flow volume. Next, various aerosols were tested to select a stable and high efficient ion source and PbI{sub 2} aerosol was chosen as the most suitable one. A 4{pi}{beta}-{gamma}-coinsidence spectrometer with plastic scintillator of 1 mm in depth was constructed and simultaneous measurement for {beta}-ray and {gamma}-ray as well as measurement for a single spectre became possible. Thus identification of {sup 150}La was succeeded by those improvements of KUR-ISOL and the use of 4{pi}{beta}-{gamma}-coinsidence spectrometer. (M.N.)

  12. Systematic analysis of neutron-rich even-even carbon isotopes

    Czech Academy of Sciences Publication Activity Database

    Thiamová, Gabriela; Itagaki, N.; Otsuka, T.; Ikeda, K.

    Singapore: World Scientific, 2002 - (Kvasil, J.; Cejnar, P.; Krtička, M.), s. 837-841 [Proceedings of the International Symposium Capture Gamma-Ray Spectroscopy and Related Topics /11./. Průhonice (CZ), 02.09.2002-06.09.2002] Institutional research plan: CEZ:AV0Z1048901 Keywords : structure of light neutron-rich nuclei * new magic number of N=16 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  13. Shape coexistence measurements in even-even neutron-deficient polonium isotopes by Coulomb excitation, using REX-ISOLDE and the Ge MINIBALL array

    CERN Multimedia

    Butler, P; Bastin, B; Kruecken, R; Voulot, D; Rahkila, P J; Orr, N A; Srebrny, J; Grahn, T; Clement, E; Paul, E S; Gernhaeuser, R A; Dorsival, A; Diriken, J V J; Huyse, M L; Iwanicki, J S

    The neutron-deficient polonium isotopes with two protons outside the closed Z=82 shell represent a set of nuclei with a rich spectrum of nucleus structure phenomena. While the onset of the deformation in the light Po isotopes is well established experimentally, questions remain concerning the sign of deformation and the magnitude of the mixing between different configurations. Furthermore, controversy is present with respect to the transition from the vibrational-like character of the heavier Po isotopes to the shape coexistence mode observed in the lighter Po isotopes. We propose to study this transition in the even-mass neutron-deficient $^{198,200,202}$Po isotopes by using post-accelerated beams from REX-ISOLDE and "safe"-energy Coulomb excitation. $\\gamma$- rays will be detected by the MINIBALL array. The measurements of the Coulomb excitation differential cross section will allow us to deduce both the transition and diagonal matrix elements for these nuclei and, combined with lifetime measurements, the s...

  14. Maximum abundant isotopes correlation

    International Nuclear Information System (INIS)

    The neutron excess of the most abundant isotopes of the element shows an overall linear dependence upon the neutron number for nuclei between neutron closed shells. This maximum abundant isotopes correlation supports the arguments for a common history of the elements during nucleosynthesis. (Auth.)

  15. Evidence for reduced collectivity around the neutron mid-shell in the stable even-mass Sn isotopes from new lifetime measurements

    International Nuclear Information System (INIS)

    Precise measurements of the lifetimes of the first excited 2+ states in the stable even-A Sn isotopes 112-124Sn have been performed using the Doppler shift attenuation technique. For the isotopes 112Sn, 114Sn and 116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously reported values and indicate a shallow minimum at N=66. The observed deviation from a maximum at mid-shell is attributed to the obstructive effect of the s1/2 neutron orbital in generating collectivity when near the Fermi level.

  16. Beta-decay half-lives of neutron rich Cu and Ni isotopes produced by thermal fission of 235U and 239Pu

    International Nuclear Information System (INIS)

    The half-lives of very neutron rich isotopes of Ni and Cu have been measured. The isotopes are produced in very asymmetric thermal fission of 235U and 239Pu at the I.L.L. high flux reactor. They are separated by means of the Lohengrin spectrometer. They are identified with a ΔE-E ionization chamber and implanted in one of the 8 Si planar detectors where the β- particles are also detected. The time correlations between the implantation and the detection of β- particles provide the half-life. The values obtained are compared to current theoretical predictions

  17. Neutron field characteristics of Ciemat's Neutron Standards Laboratory Hector Rene Vega-Carrillo

    OpenAIRE

    Guzmán-García, Karen Arlete; Méndez Villafañe, Roberto; Vega-Carrillo, Héctor René

    2015-01-01

    Monte Carlo calculations were carried out to characterize the neutron field produced by the calibration neutron sources of the Neutron Standards Laboratory at the Research Center for Energy, Environment and Technology (CIEMAT) in Spain. For 241AmBe and 252Cf neutron sources, the neutron spectra, the ambient dose equivalent rates and the total neutron fluence rates were estimated. In the calibration hall, there are several items that modify the neutron field. To evaluate their effects differen...

  18. Neutron Radiography

    Directory of Open Access Journals (Sweden)

    A. R. Reddy

    1982-07-01

    Full Text Available The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  19. The effect of pressure, isotopic (H/D) substitution, and other variables on miscibility in polymer-solvent systems. The nature of the demixing process; dynamic light scattering and small angle neutron scattering studies. Final report

    International Nuclear Information System (INIS)

    A research program examining the effects of pressure, isotope substitution and other variables on miscibility in polymer solvent systems is described. The techniques employed included phase equilibrium measurements and dynamic light scattering and small angle neutron scattering

  20. Shell-model states with seniority ν =3 , 5, and 7 in odd-A neutron-rich Sn isotopes

    Science.gov (United States)

    Iskra, Ł. W.; Broda, R.; Janssens, R. V. F.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Pawłat, T.; Seweryniak, D.; Stefanescu, I.; Walters, W. B.; Wrzesiński, J.; Zhu, S.

    2016-01-01

    Excited states with seniority ν =3 , 5, and 7 have been investigated in odd neutron-rich 119,121,123,125Sn isotopes produced by fusion-fission of 6.9-MeV/A 48Ca beams with 208Pb and 238U targets and by fission of a 238U target bombarded with 6.7-MeV/A 64Ni beams. Level schemes have been established up to high spin and excitation energies in excess of 6 MeV, based on multifold gamma-ray coincidence relationships measured with the Gammasphere array. In the analysis, the presence of isomers was exploited to identify gamma rays and propose transition placements using prompt and delayed coincidence techniques. Gamma decays of the known 27 /2- isomers were expanded by identifying new deexcitation paths feeding 23 /2+ long-lived states and 21 /2+ levels. Competing branches in the decay of 23 /2- states toward two 19 /2- levels were delineated as well. In 119Sn, a new 23 /2+ isomer was identified, while a similar 23 /2+ long-lived state, proposed earlier in 121Sn, has now been confirmed. In both cases, isomeric half-lives were determined with good precision. In the range of ν =3 excitations, the observed transitions linking the various states enabled one to propose with confidence spin-parity assignments for all the observed states. Above the 27 /2- isomers, an elaborate structure of negative-parity levels was established reaching the (39 /2- ), ν =7 states, with tentative spin-parity assignments based on the observed deexcitation paths as well as on general yrast population arguments. In all the isotopes under investigation, strongly populated sequences of positive-parity (35 /2+ ), (31 /2+ ), and (27 /2+ ) states were established, feeding the 23 /2+ isomers via cascades of three transitions. In the ,123Sn121 isotopes, these sequences also enabled the delineation of higher-lying levels, up to (43 /2+ ) states. In 123Sn, a short half-life was determined for the (35 /2+ ) state. Shell-model calculations were carried out for all the odd Sn isotopes, from 129Sn down to 119

  1. Beta-transition properties for neutron-rich Sn and Te isotopes by Pyatov method

    Indian Academy of Sciences (India)

    D I Salamov; S Unlu; N Cakmak

    2007-09-01

    Based on Pyatov's method, the low-lying Gamow–Teller (GT) 1+ state energies and log() values for 128,130,132Sb and 132,134,136I isotopes have been calculated. In this method, the strength parameter of the effective spin–isospin interaction is found by providing the commutativity of the GT operator with the central part of the nuclear Hamiltonian. The problem has been solved within the framework of RPA. The calculation results have been compared with the corresponding experimental data.

  2. Beta delayed alpha emission from the neutron deficient rare earth isotopes 152Tm and 150Ho

    International Nuclear Information System (INIS)

    The study of beta-delayed proton emission is a well known method to aid the determination of the beta strength distribution in nuclei far from the stability line. At the neutron deficient side of the nuclear chart the process of proton or alpha emission from excited states is energetically allowed when one goes far enough from stability. However, beta-delayed alphas have seldom been measured for nuclei heavier than A = 20. Here we present a study of the beta-delayed alpha-particle emission from 152Tm and 150Ho and their importance in the full B(GT) distribution.

  3. Measurements of competing structures in neutron-deficient Pb isotopes by employing Coulomb excitation

    CERN Multimedia

    Bastin, B; Kruecken, R; Larsen, A; Rahkila, P J; Srebrny, J; Clement, E; Wadsworth, R; Syed naeemul, H; Peura, P J; Siem, S; Hadynska-klek, K; Habs, D; Page, R; Napiorkowski, P J; Diriken, J V J; Iwanicki, J S

    Coulomb excitation measurements to study the shape coexistence and quadrupole collectivity of the low-lying levels in neutron-deficient Pb nuclei are proposed. Even-mass $^{188−192}$Pb nuclei will be post-accelerated at REX-ISOLDE in order to measure transition probabilities and quadrupole moments for the first excited states. In combination with results obtained in lifetime measurements, this will allow the sign of the quadrupole deformation parameter to be extracted for the first time for 2$^{+}$ states in the even-mass $^{188−192}$Pb nuclei.

  4. Shape Transition and Coexistence in Neutron-Deficient Rare Earth Isotopes

    CERN Multimedia

    We propose to study spectroscopic quadrupole moments of excited states and electromagnetic transition rates between them in the neutron-deficient rare earth nuclei $^{140}$Sm and $^{142}$Gd using projectile Coulomb excitation at energies of 4.7 MeV per nucleon. The rare earth nuclei below the N=82 shell closure form one of the few regions of the nuclear chart where oblate shapes are expected to occur near the ground state. Nuclear shapes are expected to change rapidly in this region, with coexistence of oblate and prolate shapes in some nuclei. The measurement of electromagnetic matrix elements represents therefore a particularly sensitive test of theoretical nuclear structure models.

  5. Study of oblate nuclear shapes and shape coexistence in neutron-deficient rare earth isotopes

    CERN Multimedia

    Guttormsen, M S; Reiter, P; Larsen, A; Korten, W; Clement, E; Siem, S; Renstrom, T; Buerger, A; Jenkins, D G

    We propose to investigate nuclear shapes and shape coexistence in neutron-deficient rare earth nuclei below the N=82 shell closure at the ISOLDE facility by employing Coulomb excitation of Nd, Sm, Gd, and Dy beams from the REX accelerator and the Miniball experiment. Nuclear shapes are expected to change rapidly in this region of the nuclear chart. The measurement of electric quadrupole moments of excited states and the transition rates between them serves as a stringent test of theoretical models and effective nucleon-nucleon interactions.

  6. Biopolymer deuteration for neutron scattering and other isotope-sensitive techniques.

    Science.gov (United States)

    Russell, Robert A; Garvey, Christopher J; Darwish, Tamim A; Foster, L John R; Holden, Peter J

    2015-01-01

    The use of microbial biosynthesis to produced deuterated recombinant proteins is a well-established practice in investigations of the relationship between molecular structure and function using neutron scattering and nuclear magnetic resonance spectroscopy. However, there have been few reports of using microbial synthetic capacity to produce labeled native biopolymers. Here, we describe methods for the production of deuterated polyhydroxyalkanoate biopolyesters in bacteria, the polysaccharide chitosan in the yeast Pichia pastoris, and cellulose in the bacterium Gluconacetobacter xylinus. The resulting molecules offer not only multiple options in creating structural contrast in polymer blends and composites in structural studies but also insight into the biosynthetic pathways themselves. PMID:26577729

  7. Neutron-capture cross sections of the tungsten isotopes 182W, 183W, 184W, and 186W from 2.6 to 2000 keV

    International Nuclear Information System (INIS)

    Neutron-capture cross sections of four stable tungsten isotopes were measured as a function of energy by time of flight at the Oak Ridge Electron Linear Accelerator. The resolution achieved, ΔE/E about 1/750 FWHM, has allowed the analysis of several hundred resonance peaks at energies a few kiloelectron volts above the neutron-binding energy. Strength functions were fitted to the average cross sections up to about 100 keV, and average cross sections were extended with less precision from 100 to 2000 keV. The capture cross section of natural tungsten was calculated from measurements for individual isotopes. Compound nucleus calculations have been made with deformed optical model parameters for comparison with experimental cross sections

  8. Quantitative study of coherent pairing modes with two neutron transfer: Sn-isotopes

    CERN Document Server

    Potel, G; Barranco, F; Vigezzi, E; Broglia, R A

    2012-01-01

    Pairing rotations and pairing vibrations are collective modes associated with a field, the pair field, which changes the number of particles by two. Consequently, they can be studied at profit with the help of two-particle transfer reactions on superfluid and in normal nuclei, respectively. The advent of exotic beams has opened, for the first time, the possibility to carry out such studies in medium heavy nuclei, within the same isotopic chain. In the case studied in the present paper that of the Sn-isotopes (essentially from closed (Z=N=50) to closed (Z=50,N=82) shells). The static and dynamic off-diagonal, long range order phase coherence in gauge space displayed by pairing rotations and vibrations respectively, leads to coherent states which behave almost classically. Consequently, these modes are amenable to an accurate nuclear structure description in terms of simple models containing the right physics, in particular BCS plus QRPA and HF mean field plus RPA respectively. The associated two- nucleon trans...

  9. Measurement of beta decay periods for Fe-Ni neutrons rich isotopes

    International Nuclear Information System (INIS)

    Thermal fission of 239 Pu was used to produce 68,69 Co and 68 Fe isotopes, the lightest ones ever observed in thermal fission, at the ILL high-flux reactor, in Grenoble. Separated with the Lohengrin recoil spectrometer, then identified by means of a Δ E-E ionization chamber, fragments were implanted in a set of Si-detectors, where β-particles were detected too. The fission yields were determined, and the beta-decay half-lives were extracted from delayed coincidence analysis between ion implantation and the subsequent beta detection: They were found to be 0.27±0.05s, 0.18±0.10s, and 0.10±0.06s respectively for 69 Co, 68 Co, and 68 Fe. This method was adapted to a new experimental configuration: 65 Fe isotopes were produced from 86 Kr projectile fragmentation at 500 MeV/u on a Be target. Selected ions were separated with the fragment separator FRS at GSI (Darmstadt), tuned in the monoenergetic mode. Fragments were identified by ΔE-ToF, slowed down, and then implanted in two rows of PIN-diodes that provided an additional range selection. The half-life were determined from the analysis of the decay chain Fe-Co-Ni: it was found 0.4±0.2s. Production rates obtained with the two methods are compared at the end of this work

  10. Study of neutron-deficient isotopes of Fl in the 239Pu, 240Pu + 48Ca reactions

    Science.gov (United States)

    Voinov, A. A.; Utyonkov, V. K.; Brewer, N. T.; Oganessian, Yu Ts; Rykaczewski, K. P.; Abdullin, F. Sh; Dmitriev, S. N.; Grzywacz, R. K.; Itkis, M. G.; Miernik, K.; Polyakov, A. N.; Roberto, J. B.; Sagaidak, R. N.; Shirokovsky, I. V.; Shumeiko, M. V.; Tsyganov, Yu S.; Subbotin, V. G.; Sukhov, A. M.; Sabelnikov, A. V.; Vostokin, G. K.; Hamilton, J. H.; Stoyer, M. A.; Strauss, S. Y.

    2016-07-01

    The results of the experiments aimed at the synthesis of Fl isotopes in the 239Pu + 48Ca and 240Pu + 48Ca reactions are presented. The experiment was performed using the Dubna gas-filled recoil separator at the U400 cyclotron. In the 239Pu+48Ca experiment one decay of spontaneously fissioning 284Fl was detected at 245-MeV beam energy. In the 240Pu+48Ca experiment three decay chains of 285Fl were detected at 245 MeV and four decays were assigned to 284Fl at the higher 48Ca beam energy of 250 MeV. The α-decay energy of 285Fl was measured for the first time and decay properties of its descendants 281Cn, 277Ds, 273Hs, 269Sg, and 265Rf were determined more precisely. The cross section of the 239Pu(48Ca,3n)284Fl reaction was observed to be about 20 times lower than those predicted by theoretical models and 50 times less than the value measured in the 244Pu+48Ca reaction. The cross sections of the 240Pu(48Ca,4-3n)284,285Fl at both 48Ca energies are similar and exceed that observed in the reaction with lighter isotope 239Pu by a factor of 10. The decay properties of the synthesized nuclei and their production cross sections indicate rapid decrease of stability of superheavy nuclei with departing from the neutron number N=184 predicted to be the next magic number.

  11. Microscopic description of fission in neutron-rich plutonium isotopes with the Gogny-D1M energy density functional

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Guzman, R. [Rice University, Department of Physics and Astronomy, Houston, Texas (United States); Rice University, Department of Chemistry, Houston, Texas (United States); Robledo, L.M. [Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain)

    2014-09-15

    The most recent parametrization D1M of the Gogny energy density functional is used to describe fission in the isotopes {sup 232-280}Pu. We resort to the methodology introduced in our previous studies (Phys. Rev. C 88, 054325 (2013) and Phys. Rev. C 89, 054310 (2014)) to compute the fission paths, collective masses and zero point quantum corrections within the Hartree-Fock-Bogoliubov framework. The systematics of the spontaneous fission half-lives t{sub SF}, masses and charges of the fragments in plutonium isotopes is analyzed and compared with available experimental data. We also pay attention to isomeric states, the deformation properties of the fragments as well as to the competition between the spontaneous fission and α-decay modes. The impact of pairing correlations on the predicted t{sub SF} values is demonstrated with the help of calculations for {sup 232-280}Pu, in which the pairing strengths of the Gogny-D1M energy density functional are modified by 5% and 10%, respectively. We further validate the use of the D1M parametrization through the discussion of the half-lives in {sup 242-262}Fm. Our calculations corroborate that, though the uncertainties in the absolute values of physical observables are large, the Gogny-D1M Hartree-Fock-Bogoliubov framework still reproduces the trends with mass and/or neutron numbers and therefore represents a reasonable starting point to describe fission in heavy nuclear systems from a microscopic point of view. (orig.)

  12. Probing the shell closure at N = 32 by mass measurements of neutron-rich potassium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbusch, M. [Ernst-Moritz-Arndt-Universitaet Greifswald (Germany); Collaboration: ISOLTRAP-Collaboration

    2014-07-01

    The Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN has been set up for precision mass measurements of short-lived nuclides and has been continuously improved for accessing more exotic nuclides. A crucial step forward has been made with the installation of a multi-reflection time-of-flight mass separator (MR-ToF MS), which enables high-resolution mass separation of contaminated ions, resulting, e.g., in the measurement of {sup 82}Zn. More recently, mass measurements have been performed directly in the MR-ToF MS instead of using a Penning trap. This paved the way for the mass determination of {sup 53,54}Ca, which would not have succeeded in ISOLTRAP's Penning traps. The obtained two-neutron separation energies (S{sub 2n}) unambiguously confirm a shell closure at N = 32, indicated earlier by measurements of the excitation energies of the first 2{sup +} state in {sup 52}Ca. In addition, with the MR-ToF MS at ISOLTRAP the masses of {sup 52}K and {sup 53}K have been determined for the first time. With a half-life of only 30 ms, {sup 53}K is the shortest-lived nuclide ever investigated at ISOLTRAP. The data are currently under evaluation. In this contribution, the new S{sub 2n} values are presented, and the crossing of the neutron shell closure at N = 32 for potassium is discussed.

  13. Gamma spectroscopic studies of some neutron deficient even Te and Pb isotopes

    International Nuclear Information System (INIS)

    In this thesis the results of an extensive experimental study of the nuclei 118120Te and 196Pb by means of in-beam gamma and electron spectroscopic methods are presented. In Chapter II a survey is given of the experimental methods applied to obtain information on properties of excited states of these nuclei. How nuclear structure studies on states accessible with these methods can benefit from the simultaneous measurement of the total energy of the γ-cascade connecting the entry point and the relevant excited state is discussed briefly in Chapter III. The design and the performance of the six detector NaI(Tl) sumspectrometer with which these measurements are carried out is described also in this chapter. Since the NaI(Tl) sumspectrometer is sensitive not only to gamma-rays but also to neutrons which are inevitably present in ( H.I.,xnγ) reactions, the author describes in Chapter IV the experimental determination of the response of large NaI(Tl) detectors to neutrons with energies 0.7 118120Te and 196Pb, and a discussion of the experimental results in terms of nuclear models (IBA and broken pair model) are presented. (Auth.)

  14. Interaction of slow neutrons with the second isomeric level Kπ=16+ of the 178Hf isotope

    International Nuclear Information System (INIS)

    In this work, we study the interaction of low energy neutrons (E≤ 10 eV) with the second isomeric level of 178Hf (lπ=Kπ=16+, T1/2=31 y) in (n,γ) reactions which proceed through the formation of a compound nucleus. The radiative decay of high K states in 179Hf is investigated using an isomeric Iπ =16+ 178Hf target, 40 ng in weight. The first experiment, performed at the high flux reactor in the Laue Langevin Institute in Grenoble, consisted in γ-ray spectroscopy measurements. For this purpose, an experimental set-up has been built. lt consists of four large Ge detectors shielded against background using a specific F6Li collimations ensemble. The second experiments performed at the Fakel (Kurchatov lnstitute, Moscow) and Gelina (IRMM Geel, Belgium) linear accelerators consisted in the investigation of neutron resonances in the 178Hfm2 (n,γ) reaction using time of flight technique and their γ-decay paths. A high efficiency spectrometer has been built and used for the measurements at bath sites. Two resonances located at 1.82 eV and 0.75 eV have been observed and unambiguously assigned to the (n+178Hfm2) compound system. The γ-decay properties of these resonances are very different. Furthermore, the γ-decay path followed by the 0.75 eV resonance is at odd with that expected form statistical model predictions. (author)

  15. Evaluation of neutron cross sections for the Pd isotopes (RCN-3 data library)

    International Nuclear Information System (INIS)

    The evaluation procedure to obtain neutron cross sections of 102Pd, 104Pd, 105Pd, 106Pd, 107Pd, 108Pd and 110Pd for inclusion in the RCN-3 data library of fission-product cross sections is described. The new evaluation takes into account the results of recent differential and integral data. Most of the adopted resolved resonance parameters have been taken from the new CBNM measurements; for 107Pd the recent RPI data have been used. These resolved resonance parameters have been extensively analysed to obtain average values for the level spacing, capture width and neutron s- and p-wave strength functions. The systematics of the single-particle level-density parameter α and the capture width show significant odd-even effects. Optical-model and statistical-model calculations have been performed to obtain cross sections of reactions at energies from 1 meV to 15 MeV. The results for the capture cross sections based upon the analysed average resonance parameters turned out to be systematically lower than the ORELA average capture data and also lower than indicated by the most integral STEK data (except for 105Pd). As a compromise we have performed adjustments to increase the calculated fast capture cross sections for 104Pd, 106Pd and 108Pd

  16. Transmission and Reflection of Neutrons Using Foil Activation Technique

    International Nuclear Information System (INIS)

    A new neutron irradiation facility has been designed, constructed .and located at the Experimental Nuclear Physics Department, NRC, AEA, cairo. The neutrons were obtained from CNIF2 (Second Cairo Neutron Irradiation Facility) that is based on one 241 Am-Be(α, n) isotopic neutron source with a present activity of about 175 GBq results in a neutron yield of about 1.04 x107 n/s. The geometrical arrangements of the facility consider the safety and protection rules aspects. MCNP5 code is used to estimate radiation doses and neutron fluxes. This new irradiation facility provides fast and epithermal neutrons that can be used in basic research and industrial applications. The aim of the present work is to study the characteristics of this new irradiation facility and to develop methods able to use fast and epithermal neutron in some different applications. Experimental measurements for the transmission and reflection of neutrons were carried out via a number of hydrogenous materials using the activation foil technique. A comparison of the experimental results with that calculated by using Monte Carlo simulation method is presented Using the neutron transmission technique in combination with foil activation method, our arrangement is used to measure the total neutron microscopic cross-sections for some compounds. The facility is calibrated and suitable to estimate the hydrogen content H (wt %) and the weight ratios C/H in hydrocarbon materials and was used to measure these ratios for some Egyptian crude oil samples. A brief overview of the neutron activation analysis methods for elemental concentrations in bulk samples in natural conditions is presented.

  17. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    Energy Technology Data Exchange (ETDEWEB)

    Pajtler, M. Varga, E-mail: maja.varga@fizika.unios.hr [Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, 31000 Osijek (Croatia); Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N. [Ruer Bošković Institute, HR-10001, Zagreb (Croatia); Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Gadea, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Haas, F. [Institut Pluridisciplinaire Hubert Curien, CNRS-IN2P3 and Université de Strasbourg, F-67037 Strasbourg (France); Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Märginean, N. [Horia Hulubei National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Magurele (Romania); Pollarolo, G. [Dipartimento di Fisica Teorica, Universitá di Torino,and Istituto Nazionale di Fisica Nucleare, I-10125 Torino (Italy); and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  18. A New High Energy Resolution Neutron Transmission Detector at the Gaerttner LINAC Center and Isotopic Molybdenum Total Cross Section Measurements in the keV-Region

    Science.gov (United States)

    Bahran, Rian M.

    The Gaerttner LINAC Center at Rensselaer Polytechnic Institute is home to a 60 MeV electron linear accelerator (LINAC) that is used as a pulsed neutron source for TOF nuclear data experiments. High energy resolution total cross section measurements for the stable molybdenum isotopes of Mo-95, Mo-96, Mo-98, and Mo-100 were performed with a newly developed modular neutron transmission detector positioned at a 100 m experimental flight station. This work is part of an effort to both improve existing neutron total cross section libraries and measurement capabilities at the Gaerttner LINAC Center in and above the resolved resonance energy region (from 5-620 keV). The overall design optimization process and qualification of the new high resolution detector is presented. Additionally, a new method to quantify the energy-dependent neutron and gamma-ray experimental background of the detector was developed. High resolution isotopic molybdenum total cross section data are of particular importance because stable Mo isotopes can be found in significant concentrations in a nuclear fuel cycle either as a high yield fission product or in alloyed form with applications in reactor piping, fuel cladding, and as an advanced nuclear fuel in the form of U-Mo. The measured total cross section energy range encompasses the resolved resonance region and extends into the unresolved resonance region for each molybdenum isotope. New high accuracy resonance parameters for Mo-95 were generated from fitting experimental data using the multilevel R-matrix Bayesian code SAMMY in the resolved resonance region. In the unresolved resonance region, average resonance parameters and fits to the total cross section were obtained using the Hauser-Feshbach statistical model code FITACS which is embedded in SAMMY.

  19. Systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes with the Gogny energy density functional

    OpenAIRE

    Rodriguez-Guzman, R.; Sarriguren, Pedro; Robledo, L. M.

    2010-01-01

    The systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes is studied within the Hartree-Fock-Bogoliubov plus equal filling approximation method preserving both axial and time-reversal symmetries. Calculations based on the Gogny energy density functional with both the standard D1S parametrization and the new D1M incarnation of this functional are included in our analysis. The nuclear deformation and shape coexistence inherent to this mass region are shown ...

  20. Fission Yields of Some Isotopes in the Fission of Th232 by Reactor Neutrons

    International Nuclear Information System (INIS)

    The fission yields of the longer-lived isotopes produced in the fission of Th232 are not very well known; existing data show rather large discrepancies and/or uncertainties. Since we feel that at least some of these discrepancies arise from difficulties in measuring the absolute activities of the fission products, we measured the fission yield of 10 selected isotopes whose decay schemes are well understood. The thorium foils were irradiated in a position at the edge of the core of the SAPHIR swimming pool reactor. Following irradiation, the thorium was dissolved after addition of appropriate carriers. The fission products of interest were determined by conventional radiochemical methods that had to be modified slightly to ensure good decontamination from the abundantly formed Pa233 . The chemical yields were determined by gravimetric methods. Counting was done preferentially on a γ-spectrometer that had been calibrated at 11 different energies by standards either obtained from the IAEA or prepared by 4πβ-counting. In the case of Sr90, Ru106 and Ce144 a β-proportional counter was used that had been calibrated for these isotopes. In addition to the sought elements, Mo99 was isolated from each foil to serve as an internal monitor for the number of fissions taking place. The experiment thus gave the ratio of the yield of the sought element to the yield of Mo99. This ratio ''R'' was obtained for Sr90, Ru103, Ru106, Ag111, Pd112, I131, Cs137, Ba140, Ba141, Ce141 and Ce144, Results indicate the existence of a third peak in the yield mass curve in the region of symmetric fission. Yields of fission products relative to the Mo99 yields are given, and the absolute yields calculated by assuming y Mo99 = 2.78%. This number was derived from the work of Iyer et al., and was obtained by normalizing the area under the yield mass curve to 200%. (author)

  1. Neutron spectra and dosimetric assessment around a neutron Howitzer container

    OpenAIRE

    Barros, Silvia; Gallego Díaz, Eduardo F.; Lorente Fillol, Alfredo; Gonçalves, Isabel F.; Vaz, Pedro; Vega-Carrillo, Héctor René; Zankl, María

    2014-01-01

    The neutron Howitzer container at the Neutron Measurements Laboratory of the Nuclear Engineering Department of the Polytechnic University of Madrid (UPM), is equipped with a 241Am-Be neutron source of 74 GBq in its center. The container allows the source to be in either the irradiation or the storage position. To measure the neutron fluence rate spectra around the Howitzer container, measurements were performed using a Bonner spheres spectrometer and the spectra were unfolded using the NSDann...

  2. Magicity of neutron-rich isotopes within relativistic self-consistent approaches

    CERN Document Server

    Li, Jia Jie; Long, Wen Hui; Van Giai, Nguyen

    2016-01-01

    The formation of new shell gaps in intermediate mass neutron-rich nuclei are investigated within the relativistic Hartree-Fock-Bogoliubov theory and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy-Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the formation of the $N=16$, 32 and 34 shell gaps. The nuclei $^{24}$O, $^{52,54}$Ca and $^{48}$Si are predicted with a large shell gap and zero ($^{24}$O, $^{52}$Ca) or almost zero ($^{54}$Ca, $^{48}$Si) pairing gap, making them candidates for new magic numbers in exotic nuclei. We found from our analysis that the Lorentz pseudo-vector and tensor interactions induce very specific evolutions of single-particle energies, which could clearly sign their presence and reveal the need for relativistic approaches with exchange interactions.

  3. Microscopic study of deformed neutron-deficient 124-132Ce isotopes

    International Nuclear Information System (INIS)

    Variation after Projection calculations in conjunction with Hartree Bogoliubov Ansatz have been carried out for 124-132Ce mass chain. In this framework, the yrast spectra, B(E2) transition probabilities and occupation numbers for various shell model orbits have been obtained. The observed decrease in deformation in going from 124Ce to 132Ce is seen to arise due to a slow decrease in the occupation of 1g7/2 proton orbit and a systematic increase in the occupations of 2d5/2, 1g7/2 and 1h11/2 neutron orbits. Besides this, the experimental low-lying yrast spectra and B(E2) transition probabilities are reproduced with reasonable accuracy by using PQOH interaction. (author)

  4. Isotope identification of Saudi Arabian rock samples from Umm Al-Birak using neutron activation analysis

    International Nuclear Information System (INIS)

    Forty eight geological samples from Umm Al-Birak area in the northwest part of Saudi Arabia are analyzed qualitatively and quantitatively using the instrumental neutron activation analysis technique. Samples are properly prepared and irridiated in the reactor facilities of the National Tsing-Hue University in Taiwan. Gamma spectra from high resolution detector are analyzed using BRUTAL code. Final calculations are made by two independent programs, namely, ELCAL and SMPCL. Twenty trace elements are identified and their concentrations are used in the investigation of the geochemistry of the Umm Al-Birak microgranite site. These elements are: Co, Cr, Eu, Fe, Hf, K, La, Lu, Na, Rb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr. It is shown that high grade area is a differentiated rock that crystallized in a late stage of Umm Al-Birak microgranite area. 43 Ref

  5. ${\\beta}$-decay studies of neutron-rich $^{61-70}$Mn isotopes with the new LISOL ${\\beta}$-decay setup

    CERN Multimedia

    Diriken, J V J

    2008-01-01

    The aim of this proposal is to gather new information that will serve as benchmark to test shell model calculations in the region below $^{68}$Ni, where proper residual interactions are still under development. More specifically, the ${\\beta}$-decay experiment of the $^{61-70}$Mn isotopes will highlight the development of collectivity in the Fe isotopes and its daughters. At ISOLDE, neutron-rich Mn isotopes are produced with a UC$_{x}$ target and selective laser ionization. These beams are particularly pure and reasonable yields are obtained for the neutron-rich short lived $^{61-70}$Mn isotopes. We propose to perform ${\\beta}$-decay studies on $^{61-70}$Mn utilizing the newly-developed "LISOL ${\\beta}$-decay setup", consisting of two MINIBALL cluster Ge detectors and a standard tape station. The use of digital electronics in the readout of these detectors enables us to perform a "slow correlation technique" which should indicate the possible existence of isomers in the daughter nuclei.

  6. Isoscalar and neutron modes in the E1 spectra of Ni isotopes and the relevance of shell effects and the continuum

    CERN Document Server

    Papakonstantinou, P; Roth, R

    2015-01-01

    We study theoretically the electric dipole transitions of even Ni isotopes at low energies, using the self-consistent quasi-particle random-phase approximation (RPA) with the D1S Gogny interaction and a continuum-RPA model with the SLy4 Skyrme force. We analyze isoscalar states, isovector states, and the dipole polarizability. We define a reference value for the polarizability, to remove a trivial dependence on the mass number. We compare our results with data and other calculations, with a focus on collective states, shell effects, and threshold transitions. Our results support the presence of a strong isoscalar transition, with little or moderate E1 strength, as a universal feature of ordinary nuclei. In moderately neutron-rich Ni isotopes, namely 68Ni and neighboring isotopes, this transition is found bimodal due to couplings with surface neutrons. An adequate treatment of the continuum states appears essential for describing suprathreshold E1 strength, especially beyond 68Ni. Very exotic isotopes (N>50) a...

  7. The pseudo-spin symmetry in Zr and Sn isotopes from the proton drip line to the neutron drip line

    CERN Document Server

    Meng, J; Yamaji, S; Arima, A

    1999-01-01

    Based on the Relativistic continuum Hartree-Bogoliubov (RCHB) theory, the pseudo-spin approximation in exotic nuclei is investigated in Zr and Sn isotopes from the proton drip line to the neutron drip line. The quality of the pseudo-spin approximation is shown to be connected with the competition between the centrifugal barrier (CB) and the pseudo-spin orbital potential (PSOP). The PSOP depends on the derivative of the difference between the scalar and vector potentials $dV/dr$. If $dV/dr = 0$, the pseudo-spin symmetry is exact. The pseudo-spin symmetry is found to be a good approximation for normal nuclei and to become much better for exotic nuclei with highly diffuse potential, which have $dV/dr \\sim 0$. The energy splitting of the pseudo-spin partners is smaller for orbitals near the Fermi surface (even in the continuum) than the deeply bound orbitals. The lower components of the Dirac wave functions for the pseudo-spin partners are very similar and almost equal in magnitude.

  8. Structural investigation of liquid formic acid by neutron diffraction. II: Isotopic substitution for DCOO[H/D

    International Nuclear Information System (INIS)

    New measurements of neutron diffraction data for four samples involving H/D isotopic substitution on the hydroxyl hydrogen of liquid formic acid at 20 deg C are reported. The results are combined with earlier measurements on [H/D]COOD to provide a full range of data. The determination of molecular conformation and bond-lengths has been made with a partial form-factor formalism and also using the 'Monte Carlo determination of g(r)' technique. The partial real-space correlation functions, RR, RH and HH are evaluated in each case and compared with existing computer simulations. The results confirm the strongly hydrogen-bonded nature of the liquid, but show that current molecular dynamics predictions based on transferable potentials do not give a very good representation of the structure. The observations provide a basis for a more detailed investigation and work is currently in progress. Ab initio quantum chemical calculations showed that the non-planar configuration suggested by Bertagnolli et al. [Ber. Bunsen. Phys. Chem. 88 (1984) 977; Ber. Bunsen. Phys. Chem. 89 (1985) 500], is very unlikely both for formic acid dimers and monomers

  9. Nuclear breathing mode in neutron-rich Nickel isotopes: sensitivity to the symmetry energy and the role of the continuum

    CERN Document Server

    Piekarewicz, J

    2014-01-01

    In this new era of radioactive beam facilities, the discovery of novel modes of excitation in nuclei far away from stability represents an area of intense research activity. In addition, these modes of excitation appear to be sensitive to the uncertain density dependence of the symmetry energy. We study the emergence, evolution, and nature of both the soft and giant isoscalar monopole modes as a function of neutron excess in three unstable Nickel isotopes: 56Ni, 68Ni, and 78Ni. The distribution of isoscalar monopole strength is computed in a relativistic random-phase approximation using several accurately calibrated effective interactions. In particular, a non-spectral Green's function approach is adopted that allows for an exact treatment of the continuum without any reliance on discretization. The discretization of the continuum is neither required nor admitted. In the case of 56Ni, the lack of low-energy strength results in a direct correlation between the centroid energy of the giant monopole resonance an...

  10. Tetrahedral shapes of neutron-rich Zr isotopes from multidimensionally-constrained relativistic Hartree-Bogoliubov model

    CERN Document Server

    Zhao, Jie; Zhao, En-Guang; Zhou, Shan-Gui

    2016-01-01

    We develop a multidimensionally-constrained relativistic Hartree-Bogoliubov (MDC-RHB) model in which the pairing correlations are taken into account by making the Bogoliubov transformation. In this model, the nuclear shape is assumed to be invariant under the reversion of $x$ and $y$ axes, i.e., the intrinsic symmetry group is $V_4$ and all shape degrees of freedom $\\beta_{\\lambda\\mu}$ with even $\\mu$ are included self-consistently. The RHB equation is solved in an axially deformed harmonic oscillator basis. A separable pairing force of finite range is adopted in the MDC-RHB model. The potential energy curves of neutron-rich even-even Zr isotopes are calculated. The ground state shapes of $^{108-112}$Zr are predicted to be tetrahedral with both functionals DD-PC1 and PC-PK1 and $^{106}$Zr is also predicted to have a tetrahedral ground state with the functional PC-PK1. The tetrahedral ground states are caused by large energy gaps at $Z=40$ and $N=70$ when $\\beta_{32}$ deformation is included. Although the incl...

  11. Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 21+ State in 80Zn

    International Nuclear Information System (INIS)

    Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 21+ state in 78Zn could be firmly established and for the first time the 2+→01+ transition in 80Zn was observed at 1492(1) keV. B(E2,21+→01+) values were extracted for 74,76,78,80Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni

  12. Coulomb excitation of $^{94,96}$Kr beam Deformation in the neutron-rich krypton isotopes

    CERN Multimedia

    Hass, M; Cederkall, J A; Di julio, D D; Zamfir, N - V; Srebrny, J; Wadsworth, R; Siem, S; Marginean, R; Iwanicki, J S

    Recently the energy of the 2$_{1}^{+}$ state in the N=60 $^{96}$Kr nucleus was determinated to be 241 keV. This was the first experimental observation of an excited state in this highly exotic nucleus. The 2$_{1}^{+}$ state in $^{94}$Kr is located at 665.5 keV, i.e. E(2$_{1}^{+}$) drops by more than 400 keV at N=60. This lowering of the 2$_{1}^{+}$ energy indicates a sharp shape transition behavior which is somewhat similar to that discovered in the Sr and Zr isotopic chains at N=60. The deformation expected for the 2$_{1}^{+}$ state of $^{96}$Kr, as resulting from the E(2$_{1}^{+}$) energy based on the semi-empirical relation of Raman et al. is $\\beta_{2}$ = 0.31, which is, however, considerably smaller than that for Sr and Zr ($\\geq$0.40). The sudden decrease of E(2$_{1}^{+}$) from N=50 to N=60 does not fully agree with the more gradual change of deformation deduced from laser spectroscopy measurements of mean square charge radii, although for $^{96}$Kr, in particular, these are consistent with a $\\beta_{2}...

  13. Neutron, Proton and Alpha Emission Spectra of Nickel Isotopes for Proton Induced Reactions

    Science.gov (United States)

    Tel, E.; Kara, A.

    2012-06-01

    The fusion energy is attractive as an energy source because the fusion will not produce CO2 or SO2 and so fusion will not contribute to environmental problems, such as particulate pollution and excessive CO2 in the atmosphere. The fusion reaction does not produce radioactive nuclides and it is not self-sustaining, as is a fission reaction when a critical mass of fissionable material is assembled. Since the fusion reaction is easily and quickly quenched the primary sources of heat to drive such an accident are heat from radioactive decay and heat from chemical reactions. Both the magnitude and time dependence of the generation of heat from radioactive decay can be controlled by proper selection and design of materials. Nickel (Ni) is an important structural material in fusion (and also fission) reactor technologies and many other fields. So, the working out the reaction cross sections of the Ni isotopes is very important for selection of the fusion materials. In this study, 58Ni(p,xn), 58Ni(p,xp), 60Ni(p,xp), 60Ni(p,xα) and 62Ni(p,xp) reactions have been investigated using nuclear reaction models. And also the 58Ni(p,xn) reaction has been calculated through a method of offered by Tel et al. The calculated results are discussed and compared with the experimental data taken from EXFOR database.

  14. Beta-delayed proton emission in neutron-deficient lanthanide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Wilmarth, P.A.

    1988-09-30

    Forty-two ..beta..-delayed proton precursors with 56less than or equal toZless than or equal to71 and 63less than or equal toNless than or equal to83 were produced in heavy-ion reactions at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decay properties studied at the on-line mass separation facility OASIS. Twenty-five isotopes and eight delayed proton branches were identified for the first time. Delayed proton energy spectra and proton coincident ..gamma..-ray and x-ray spectra were measured for all precursors. In a few cases, proton branching ratios were also determined. The precursor mass numbers were determined by the separator, while the proton coincident x-ray energies provided unambiguous Z identifications. The proton coincident ..gamma..-ray intensities were used to extract final state branching ratios. Proton emission from ground and isomeric states was observed in many cases. The majority of the delayed proton spectra exhibited the smooth bell-shaped distribution expected for heavy mass precursors. The experimental results were compared to statistical model calculations using standard parameter sets. Calculations using Nilsson model/RPA ..beta..-strength functions were found to reproduce the spectral shapes and branching ratios better than calculations using either constant or gross theory ..beta..-strength functions. Precursor half-life predictions from the Nilsson model/RPA ..beta..-strength functions were also in better agreement with the measured half-lives than were gross theory predictions. The ratios of positron coincident proton intensities to total proton intensities were used to determine Q/sub EC/-B/sub p/ values for several precursors near N=82. The statistical model calculations were not able to reproduce the experimental results for N=81 precursors. 154 refs., 82 figs., 19 tabs.

  15. Beta-delayed proton emission in neutron-deficient lanthanide isotopes

    International Nuclear Information System (INIS)

    Forty-two β-delayed proton precursors with 56≤Z≤71 and 63≤N≤83 were produced in heavy-ion reactions at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decay properties studied at the on-line mass separation facility OASIS. Twenty-five isotopes and eight delayed proton branches were identified for the first time. Delayed proton energy spectra and proton coincident γ-ray and x-ray spectra were measured for all precursors. In a few cases, proton branching ratios were also determined. The precursor mass numbers were determined by the separator, while the proton coincident x-ray energies provided unambiguous Z identifications. The proton coincident γ-ray intensities were used to extract final state branching ratios. Proton emission from ground and isomeric states was observed in many cases. The majority of the delayed proton spectra exhibited the smooth bell-shaped distribution expected for heavy mass precursors. The experimental results were compared to statistical model calculations using standard parameter sets. Calculations using Nilsson model/RPA β-strength functions were found to reproduce the spectral shapes and branching ratios better than calculations using either constant or gross theory β-strength functions. Precursor half-life predictions from the Nilsson model/RPA β-strength functions were also in better agreement with the measured half-lives than were gross theory predictions. The ratios of positron coincident proton intensities to total proton intensities were used to determine Q/sub EC/-B/sub p/ values for several precursors near N=82. The statistical model calculations were not able to reproduce the experimental results for N=81 precursors. 154 refs., 82 figs., 19 tabs

  16. A description of odd neutron-deficient cadmium isotopes within the rotor-plus-particle model using self-consistent core signle-particle states

    International Nuclear Information System (INIS)

    Single-particle wave functions as obtained from self-consistent calculations for the core are used to calculate within the rotor-plus-quasiparticle model, some spectroscopic properties of odd neutron-deficient cadmium isotopes. From constrained Hartree-Fock calculations including pairing correlations and performed with the SIII Skyrme effective force, the deformation energy curves of 98102106110Cd have been extracted together with the single-particle states corresponding to the equilibrium deformations. The projection of standard unified model wave functions onto eigenfunctions of the core angular momentum has allowed the authors to introduce exactly in the core Hamiltonian the experimental level sequence of the neigbouring even isotopes. Therefore all parameters entering the calculations are either valid for the whole chart of nuclides (effective force parameters) or unambiguously deduced from experimental data (core energies and pairing gaps). In spite of such an absence of free adjustable parameters the recently available experimental data concerning 105107109111Cd isotopes are correctly reproduced both for negative parity (as the expected hsub(11/2) decoupled band) and for positive parity states. In the 105Cd isotope, the authors have interpreted a set of positive parity levels as a gsub(7/2) decoupled band. They have also concluded that a prolate-oblate shape coexistence was probably absent in the low energy spectra of the isotopes considered. (Auth.)

  17. Design considerations for a neutron generator-based total-body irradiator

    International Nuclear Information System (INIS)

    The prompt- and delayed-gamma neutron activation techniques have been used for the non-invasive measurement of human body composition. In recent years, neutron irradiators have used only transuranic isotopic sources (238PuBe, 241AmBe, 252Cf). However, in today's security-minded environment, the use of alternate neutron sources may provide some advantages. Several designs for an irradiator that would use a high-output, miniature D-T neutron generator (MF Physics) have been examined. The use of this type of neutron source will lessen the storage, security, and transport issues associated with continuous-output isotopic neutron sources. To determine the scientific impact of this decision, Monte Carlo simulations (MCNP-4B2; Los Alamos National Laboratory) has been performed to aid in the design of the irradiator system, evaluating shielding materials, collimation, and source-to-subject distance, for the measurement of total body nitrogen (TBN). Based on internal flux distributions within the simulated body region of a subject, several design options were identified. The final design will be selected based on the optimization of precision, dose, and exposure time. (author)

  18. Automated system for neutron activation analysis determination of short lived isotopes at The DOW Chemical Company's TRIGA research reactor

    Science.gov (United States)

    Zieman, J. J.; Rigot, W. L.; Romick, J. D.; Quinn, T. J.; Kocher, C. W.

    1994-12-01

    An automated neutron activation analysis (NAA) system for the determination of short lived isotopes was constructed at The DOW Chemical Company's TRIGA Research Reactor in 1993. The NAA group of the Analytical Sciences Laboratory uses the reactor for thousands of analyses each year and therefore automation is important to achieve and maintain high throughput and precision (productivity). This project is complementary to automation of the long-lived counting facilities (see Romick et al., these Proceedings). Canberra/Nuclear Data Systems DEC-based software and electronics modules and an I/O mounting board are the basic commercial components. A Fortran program on a VAX computer controls I/O via ethernet to an Acquisition Interface Module (AIM). The AIM controls the γ spectrometer modules and is interfaced to a Remote Parallel Interface (RPI) module which controls the pneumatic transfer apparatus with TTL signals to the I/O mounting board. Near-infrared sensors are used to monitor key points in the transfer system. Spectra are acquired by a single HPGe detector mounted on a sliding rail to allow flexible and more reproducible counting geometries than with manual sample handling. The maximum sample size is 8 ml in a heat-sealed two dram vial. The sample vial is nested into a "rabbit" vial for irradiation which can be automatically removed prior to spectrum collection. The system was designed to be used by the reactor operator at the control console without the aid of an additional experimenter. Applications include the determination of selenium and silver in coal and water, fluorine in tetra-fluoro ethylene (TFE) coated membranes, aluminum and titanium in composite materials and trace fluorine in non-chlorinated cleaning solvents. Variable dead time software allows analysis for 77mSe despite high dead times from 16N encountered in samples.

  19. Automated system for neutron activation analysis determination of short lived isotopes at The DOW Chemical Company's TRIGA research reactor

    International Nuclear Information System (INIS)

    An automated neutron activation analysis (NAA) system for the determination of short lived isotopes was constructed at The DOW Chemical Company's TRIGA Research Reactor in 1993. The NAA group of the Analytical Sciences Laboratory uses the reactor for thousands of analyses each year and therefore automation is important to achieve and maintain high throughput and precision (productivity). This project is complementary to automation of the long-lived counting facilities (see Romick et al., these Proceedings). Canberra/Nuclear Data Systems DEC-based software and electronics modules and an I/O mounting board are the basic commercial components. A Fortran program on a VAX computer controls I/O via ethernet to an Acquisition Interface Module (AIM). The AIM controls the γ spectrometer modules and is interfaced to a Remote Parallel Interface (RPI) module which controls the pneumatic transfer apparatus with TTL signals to the I/O mounting board. Near-infrared sensors are used to monitor key points in the transfer system. Spectra are acquired by a single HPGe detector mounted on a sliding rail to allow flexible and more reproducible counting geometries than with manual sample handling. The maximum sample size is 8 ml in a heat-sealed two dram vial. The sample vial is nested into a 'rabbit' vial for irradiation which can be automatically removed prior to spectrum collection. The system was designed to be used by the reactor operator at the control console without the aid of an additional experimenter. Applications include the determination of selenium and silver in coal and water, fluorine in tetra-fluoro ethylene (TFE) coated membranes, aluminum and titanium in composite materials and trace fluorine in non-chlorinated cleaning solvents. Variable dead time software allows analysis for 77mSe despite high dead times from 16N encountered in samples. ((orig.))

  20. Isotope-periodic multilayer method for short self-diffusion paths - a comparative neutron and synchrotron Moessbauer reflectometric study of FePd alloys

    International Nuclear Information System (INIS)

    FePt, FePd, CoPt, and CoPd in equilibrium exhibit the L10 structure with high perpendicular magnetic anisotropy making them attractive candidates for high-density magnetic recording. Magnetic properties of these films depend on the distribution and orientation of the L10 fraction controlled by diffusion on atomic scale. Epitaxial isotope-periodic natFePd/57FePd alloy films were prepared by molecular beam epitaxy and heat treated at 5000C for various retention times. Isotope-sensitive non-destructive methods, neutron reflectometry and synchrotron Moessbauer reflectometry were applied to follow very short diffusion paths normal to the film plane. Squared diffusion lengths and diffusion profiles were obtained from the fitting of experimental reflectivity curves for each annealing treatment steps. The somewhat different diffusion lengths obtained for the neutron and synchrotronMoessbauer reflectograms of the same samples are explained by the larger footprint of the sample in the neutron experiment for which interface inhomogeneities are to be averaged. Diffusion in the microscopically different local environments were modelled by piecewise constant diffusion coefficients in the regions identified as different species by conversion electron Moessbauer spectroscopy.

  1. Comparisons of the odd–even staggering patterns between the Ba–Dy region with 88 neutrons and Ra isotopes with 88 protons

    International Nuclear Information System (INIS)

    Useful information about the shape transitions of even–even isotones 144Ba, 146Ce, 148Nd, 150Sm, 152Gd, 154Dy with 88 neutrons and 218-226Ra isotopes with 88 protons are obtained from the ratios of E(41+)/E(21+) as a function of neutron number N or proton number Z and the relations E(I1+)/E(21+) and r((I+2)/I) as a function of the angular momentum I. Interacting Boson Model (IBM-1), Bohr–Mottelson Model (BM) and Interacting Vector Boson Model (IVBM) have been employed to study the energy levels for the ground and octupole bands of the above nuclei. The best input parameters for the above approaches which lead to the best fit to experimental data are determined. The ΔI = 1 staggering (odd–even staggering) in octupole bands of the studied nuclei is found to exhibit a 'beat' behavior as a function of angular momentum I. Comparisons of the displacement energies δE(I) and the staggering factor ΔE1, γ(I) are presented between the Ba–Dy region with 88 neutrons and Ra isotopes with 88 protons. (author)

  2. Evaluation of thermal neutron cross-sections and resonance integrals of protactinium, americium, curium, and berkelium isotopes

    International Nuclear Information System (INIS)

    Data on the thermal neutron fission and capture cross-sections as well as their corresponding resonance integrals are reviewed and analysed. The data are classified according to the form of neutron spectra under investigation. The weighted mean values of the cross-sections and resonance integrals for every type of neutron spectra were adopted as evaluated data. (author). 87 refs, 2 tabs

  3. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Bruno M.; Silva, Ademir X. da, E-mail: bfreitas@nuclear.ufrj.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Martins, Marcelo M.; Pereira, Walsan W.; Mauricio, Claudia L.P., E-mail: marcelo@ird.gov.br, E-mail: walsan@ird.gov.br, E-mail: claudia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely {sup 241}Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a {sup 6}LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of {sup 241}Am-Be and {sup 252}Cf were employed, besides {sup 238}Pu-Be. Measurements were also made with scattered and moderated neutron beams, including {sup 252}Cf(D{sub 2}O) reference spectrum, {sup 241}Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  4. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    International Nuclear Information System (INIS)

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely 241Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a 6LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of 241Am-Be and 252Cf were employed, besides 238Pu-Be. Measurements were also made with scattered and moderated neutron beams, including 252Cf(D2O) reference spectrum, 241Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  5. First measurement of the radionuclide purity of the therapeutic isotope 67Cu produced by 68Zn(n,x) reaction using natC(d,n) neutrons

    International Nuclear Information System (INIS)

    We have for the first time studied the radionuclide purity of the therapeutic isotope 67Cu produced by the 68Zn(n,x)67Cu reaction. The neutrons were obtained by the natC(d,n) reaction using 40 MeV deuterons. We measured the γ-ray spectra of the reaction products produced by bombarding an enriched 68ZnO sample with the neutrons with a high-purity Ge detector. We found that the relative production yields of the impurity radionuclides 64Cu, 65Zn, and 69mZn to 67Cu are extremely low. The result indicates that the 68Zn(n,x)67Cu reaction is the most promising among those proposed routes until now for producing high-quality 67Cu, and could solve a longstanding problem of establishing an appropriate production method for 67Cu. (author)

  6. Ground state properties of neutron-rich Mg isotopes the "island of inversion" studied with laser and $\\beta$-NMR spectroscopy

    CERN Document Server

    Kowalska, M

    2006-01-01

    Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable $^{24-26}$Mg, as well as spins and magnetic moments of short-lived $^{29,31}$Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and $\\beta$-NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state $^2\\!$S$_{1/2}$ to one of the two lowest excited states $^2\\!$P$_{1/2 ,\\,3/2}$ using continuous wave laser beams. The isotope-shift measurements with fluor...

  7. Selective properties of neutron transfer reactions in the {sup 90}Zr + {sup 208}Pb system for the population of excited states in zirconium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Varga Pajtler, M., E-mail: mvarga@fizika.unios.hr [Department of Physics, University of Osijek, HR-31000 Osijek (Croatia); Szilner, S. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Corradi, L.; Angelis, G. de; Fioretto, E. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Gadea, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Haas, F. [Institut Pluridisciplinaire Hubert Curien, CNRS-IN2P3 and Université de Strasbourg, F-67037 Strasbourg (France); Lunardi, S. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Jelavić Malenica, D. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Mărginean, N. [Horia Hulubei National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Magurele (Romania); Mengoni, D. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Mijatović, T. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Montagnoli, G. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Montanari, D. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Pollarolo, G. [Dipartimento di Fisica Teorica, Universitá di Torino, and Istituto Nazionale di Fisica Nucleare, I-10125 Torino (Italy); and others

    2015-09-15

    Nuclei produced via multineutron transfer channels have been studied in {sup 90}Zr + {sup 208}Pb close to the Coulomb barrier energy in a fragment-γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ-array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to {sup 89–94}Zr isotopes. A strong population of yrast states, with energies up to ∼7.5 MeV has been observed.

  8. Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes

    International Nuclear Information System (INIS)

    Nuclei produced via multineutron transfer channels have been studied in 90Zr + 208Pb close to the Coulomb barrier energy in a fragment-γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ-array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to 89–94Zr isotopes. A strong population of yrast states, with energies up to ∼7.5 MeV has been observed

  9. Systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes with the Gogny energy density functional

    CERN Document Server

    Rodriguez-Guzman, R; Robledo, L M

    2010-01-01

    The systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes is studied within the Hartree-Fock-Bogoliubov plus Equal Filling Approximation method preserving both axial and time reversal symmetries. Calculations based on the Gogny energy density functional with both the standard D1S parametrization and the new D1M incarnation of this functional are included in our analysis. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasineutron states.

  10. Oxygen isotopes and lakes

    OpenAIRE

    Leng, Melanie; Dean, Jonathan

    2014-01-01

    Isotopes are variations of a particular chemical element. It is all to do with the number of neutrons. Oxygen has two main isotopes: 18O which has 10 neutrons and 8 protons; and 16O which has 8 neutrons and 8 protons. Although these variants have a different number of neutrons (and therefore a different atomic mass), the number of protons remains the same, and they are still classed as the same element. Isotopes are analysed in terms of ratios such as 18O/16O which is shortened to δ18O (δ...

  11. Determination of copper in some Myanmar indigenous medicines by neutron activation analysis

    International Nuclear Information System (INIS)

    Copper was determined in two Myanmar indigenous medicines by neutron activation analysis using an Am(Be) radionuclide neutron source. The activity of 511 keV peak of the 64Cu was measured. (author) 2 refs.; 2 tabs

  12. Lifetime measurement for the 21+ state in 140Sm and the onset of collectivity in neutron-deficient Sm isotopes

    Science.gov (United States)

    Bello Garrote, F. L.; Görgen, A.; Mierzejewski, J.; Mihai, C.; Delaroche, J. P.; Girod, M.; Libert, J.; Sahin, E.; Srebrny, J.; Abraham, T.; Eriksen, T. K.; Giacoppo, F.; Hagen, T. W.; Kisielinski, M.; Klintefjord, M.; Komorowska, M.; Kowalczyk, M.; Larsen, A. C.; Marchlewski, T.; Mitu, I. O.; Pascu, S.; Siem, S.; Stolarz, A.; Tornyi, T. G.

    2015-08-01

    Background: The chain of Sm isotopes exhibits a wide range of nuclear shapes and collective behavior. While the onset of deformation for N >82 has been well studied both experimentally and theoretically, fundamental data is lacking for some Sm isotopes with N Weisskopf units. The theoretical calculations are in very good agreement with the experimental result. Conclusions: The B (E 2 ;21+→01+) value for 140Sm fits smoothly into the systematic trend for the chain of Sm isotopes. The new beyond-mean field calculations are able to correctly describe the onset of collectivity in the Sm isotopes below the N =82 shell closure for the first time.

  13. Analysis of neutron-rich isotopes around the Z-38 region populated through a heavy-ion fission reaction

    OpenAIRE

    Lizarazo Sabogal, Cesar Yesid

    2014-01-01

    Abstract. The study of neutron-rich nuclei is currently one of the most active research fields in nuclear physics. The neutron excess that these nuclei contain in comparison to the stable nuclei induces new physics phenomena such as changes of the so called magic numbers given by the nuclear shell model, which leads to unexpected deformations of the nuclear shape of these nuclei far away from the stability line. In the last decades, neutron-rich nuclei with a number of protons...

  14. Design of a neutron activation system around a DD neutron generator by an analytical method and Monte Carlo simulation

    International Nuclear Information System (INIS)

    Recent developments in neutron generator technology suggest that compact instruments with high neutron yield can be used for NAA and PGNAA in combination with high count rate spectrometers. For laboratories far away from Research Reactors (RRs), such devices could serve as an alternative for training students in radioanalytical and nuclear Chemistry and certain specialized applications. As Neutron activation analysis is a well established technique with a long history of documented applications it could be made available to countries where no research reactors or other neutron irradiation facilities exist by using the proposed approach. Prompt gamma neutron activation analysis (PGNAA) is a versatile analytical tool with many applications unique to the technique. As PGNAA is generally performed at RRs external neutron guides with relatively low N flux, the proposed instrument has a potential to supplement existing PGNAA facilities far away from RRs. Neutron generators, particularly the DD-NGs, are a cost effective, easy to operate and particularly safe alternative to other neutron sources, e.g. isotopic neutron sources like Cf-252 or Am/Be. The idea to combine new developments in DD-NG with moderator/shielding and detectors for fast gamma counting emerged from a recent IAEA Coordinated Research Project (CRP) on New Developments in PGNAA, and an IAEA technical meeting on Neutron Generators for Activation Analysis Purposesis currently under preparation. We report on the design and optimization of a Neutron Activation Analysis (NAA) and a Prompt Gamma Neutron Activation Analysis (PGNAA) chamber associated with a D-D neutron generator. The nominal yield of the generator is about 1010 fast neutrons per seconds (E=2.5MeV). MCNP-Monte Carlo N-Particle Transport simulation code and analytical equation, are used to optimize the setup with respect to thermal flux and radiation protection. Many moderators such as Graphite (G), Polyethylene (Poly), Heavy water (HW), Light water

  15. First one-line mass measurements at SHIPTRAP and mass determinations of neutron-rich Fr and Ra isotopes at ISOLTRAP

    International Nuclear Information System (INIS)

    SHIPTRAP is an ion trap facility behind the velocity lter SHIP at GSI/Darmstadt. Its aim are precision studies of transuranium nuclides produced in a fusion reaction and separated by SHIP. The current set-up for high-precision mass measurements consists of three main functional parts: (i) a gas cell for stopping the energetic ions from SHIP, (ii) radiofrequency quadrupole structures to cool and to bunch the ions extracted from the gas cell, and (iii) a superconducting magnet with two cylindrical Penning traps at a eld strength of 7 T. In this work the Penning trap system has been installed and extensively characterized. The rst on-line mass measurements of short-lived nuclides were carried out and the masses of 147Er and 148Er could be experimentally determined for the rst time. Here a relative mass uncertainty of δm/m of about 1 x 10-6 was achieved. Furthermore the masses of heavy neutron-rich 229-232Ra and 230Fr isotopes have been determined with a relative mass uncertainty of about 1 x 10-7 with the ISOLTRAP mass spectometer at ISOLDE/CERN. The isotope 232Ra is the heaviest unstable nuclide ever investigated with a Penning trap. Underlying nuclear structure effects of these nuclides far from β-stability were studied by a comparison of the resulting two-neutron separation energies S2n with those given by the theoretical Infinite Nuclear Mass model. (orig.)

  16. Chemical characterization of short-lived selenium and their daughter isotopes from thermal neutron induced fission of 235U at a gas-jet facility

    International Nuclear Information System (INIS)

    Selenium nuclides are available from thermal neutron induced nuclear fission of 235U at the gas-jet facility at the Swiss spallation neutron source (SINQ) at Paul Scherrer Institute, Switzerland. The formation of stable selenium compounds, their transport yields using the gas-jet system and their relative thermal decomposition temperature were investigated under oxidizing and reducing conditions in the target chamber. Using O2, H2, CO, and propene as additional gases, the selenium isotopes are suggested to form H2SeO3, H2Se, COSe, and C3H6Se, respectively, with overall 84Se yields of 1.5%, 4.7%, 6.3%, and 21.9%, respectively. Adsorption enthalpy, vapour pressure, solubility and acidity data for these species were collected from the literature or estimated from other known thermochemical properties. Carrier free bromine isotopes (84Br, 86Br) in the form of HOBr were obtained by thermally decomposing H2SeO3 and retaining elemental Se under oxygen rich conditions on quartz at 400 K. (author)

  17. Neutron gamma fraction imaging: Detection, location and identification of neutron sources

    International Nuclear Information System (INIS)

    In this paper imaging of neutron sources and identification and separation of a neutron source from another neutron source is described. The system is based upon organic liquid scintillator detector, tungsten collimator, bespoke fast digitiser and adjustable equatorial mount. Three environments have been investigated with this setup corresponding to an AmBe neutron source, a 252Cf neutron source and both sources together separated in space. In each case, events are detected, digitised, discriminated and radiation images plotted corresponding to the area investigated. The visualised neutron count distributions clearly locate the neutron source and, relative gamma to neutron (or neutron to gamma) fraction images aid in discriminating AmBe sources from 252Cf source. The measurements were performed in the low scatter facility of the National Physical Laboratory, Teddington, UK

  18. Neutron- and proton-induced nuclear data evaluation of thorium, uranium and curium isotopes for energies up to 250 MeV

    International Nuclear Information System (INIS)

    The evaluation of neutron and proton nuclear data for thorium-232, U-233,234,236, and Cm-243,244,245,246 isotopes have been performed at energies up to 250 MeV. Neutron data was evaluated at energies from 20 MeV to 250 MeV, and combined with the JENDL-3.3 data at 20 MeV, while proton data was obtained for energies from 1 to 250 MeV. Nuclear model parameters are largely based on the IAEA-RIPL recommendation, and adjusted to better reproduce the available measurements. The coupled channel optical model was applied to calculate the total, reaction, elastic, and direct inelastic cross sections, and to obtain the transmission coefficients. Decay of excited nuclei was described with the Hauser-Feshbach and exciton models using the GNASH code to simultaneously handle neutron, proton, deuteron, triton, helium-3, α, γ emission and fissions. Special attention was paid to the fission cross sections for energies where experimental data are scant, using appropriate systematics and fittings. Particles and γ emission spectra after fission were calculated based on the statistical approach of Fong, and adjusted to the experimental data using the ALICE-ASH code. (author)

  19. Neutron- and proton-induced nuclear data evaluation of thorium, uranium and curium isotopes for energies up to 250 MeV

    CERN Document Server

    Young, Ouk Lee; Jonghwa, Chang; Konobeyev, A Yu

    2004-01-01

    The evaluation of neutron- and proton nuclear data for thorium-232, U-233,234,236, and Cm-243,244,245,246 isotopes have been performed at energies up to 250 MeV. Neutron data was evaluated at energies from 20 MeV to 250 MeV, and combined with the JENDL-3.3 data at 20 MeV while proton data was obtained for energies from 1 to 250 MeV. Nuclear model parameters are largely based on the IAEA-RIPL recommendation, and adjusted to better reproduce the available measurements. The coupled channel optical model was applied to calculate the total, reaction, elastic, and direct inelastic cross sections, and to obtain the transmission coefficients. Decay of excited nuclei was described with the Hauser-Feshbach and exciton models using the GNASH code to simultaneously handle neutron, proton, deuteron, triton, helium-3, alpha , gamma emissions and fissions. Special attention was paid on the fission cross sections for energies where experimental data are scant, using appropriate systematics and fittings. Particles and gamma e...

  20. Void distribution estimation using a neutron scattering gauge

    International Nuclear Information System (INIS)

    A neural network pattern recognition program is used to retrieve spatial phase distribution information for hydrogenous two-phase flow in a pipe from a neutron scattering gauge with multiple Am-Be sources and BF3 detectors. (orig.)