共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Andrighetto O. Bajeat A. E. Barzakh S. Essabaa D. V. Fedorov A. M. Ionan V. S. Ivanov R. Leroy G. Lhersonneau K. A. Mezilev F. V. Moroz S. Yu. Orlov V. N. Panteleev L. Stroe L. B. Tecchio A. Villari Yu. M. Volkov X. F. Wang 《The European Physical Journal A - Hadrons and Nuclei》2005,23(2):257-264
A series of on-line mass separation experiments have been performed at the IRIS facility to measure the yield and release of Rb and Cs neutron-rich isotopes produced by fission reaction of 238U. A 1 GeV proton beam was used to bombard uranium carbide targets with the densities of 11 g/cm3 and 1.5 g/cm3 held at temperatures in the range (2000-2230) °C. The release curves of Rb and Cs long-lived isotopes were measured from both kinds of targets. The overall production efficiency was determined making use of experimentally measured cross-sections of that isotope production. Comparison of the experimental yields of Rb and Cs isotopes with the calculated ones after corrections for losses due to finite release times suggests that the diffusion is the dominating process reducing the efficiency for short-lived isotopes. When normalized to the same thickness, an enhancement for the high-density rod target of the measured isotope yields is observed when going far from stability. This is possibly explained by the reactions induced by secondary neutrons. A significant odd-even effect with higher yields of Cs even neutron isotopes has been observed, confirming a similar effect obtained in earlier experiments. 相似文献
2.
Target-ion source unit ionization efficiency measurement by a method of stable ion beam implantation
V. N. Panteleev A. E. Barzakh D. V. Fedorov P. L. Molkanov F. V. Moroz S. Yu. Orlov Yu. M. Volkov 《The European physical journal. Special topics》2007,150(1):301-302
At the IRIS facility a rather precise method of the
target-ion source unit ionization efficiency measurement has been
developed. The method exploits an off-line
mass-separator for the implantation of the ion beams of selected stable isotopes into a tantalum foil placed inside a Faraday
cup
in the focal plane of the mass-separator. After the
implantation of the required amount of the investigated species, tantalum foil has been inserted into
the volume of the target-ion source unit prepared for the on-line utilization at the IRIS
on-line separator. The first tests have ensured the ionization efficiency values
(90±10)% for Rb and (85±10)% for Cs in the empty combined
target-ion source unit, which was
used as a reference one. For the target-ion source unit with UC target material inside the measured value of the ionization
efficiency of Rb was (52±20)%. 相似文献
3.
V. N. Panteleev O. Alyakrinskiy A. Andrighetto A. E. Barzakh M. Dubois C. Eleon S. Essabaa O. Bajeat D. V. Fedorov G. Gaubert A. M. Ionan V. S. Ivanov P. Jardin A. Lanchais C. Lau R. Leroy G. Lhersonneau C. Mhamed K. A. Mezilev P. L. Molkanov F. V. Moroz S. Yu. Orlov V. Rizzi M. G. Saint Laurent L. Stroe L. B. Tecchio A. C.C. Villari Yu. M. Volkov 《The European physical journal. Special topics》2007,150(1):297-300
The capacity of uranium carbide target materials of
different structure and density for production of neutron-rich and
heavy neutron-deficient nuclides have been investigated. The
yields of Cs and Fr produced by a 1 GeV proton beam of the PNPI
synchrocyclotron and release properties of different targets have
been measured. Yields and release efficiencies of Cs and Fr
produced from a high density UC target material and from low
density UCx prepared by the ISOLDE method at IRIS in the
collaboration with PARRNe group from Orsay are compared. The
yields from ISOLDE original target are presented for comparison as
well. 相似文献
4.
Mirjalili A. Yazdanpanah M. M. 《The European Physical Journal A - Hadrons and Nuclei》2011,47(5):1-10
The diffusion-effusion model has been used to analyse the release and yields of Fr and Cs isotopes from uranium carbide targets of very different thicknesses (6.3 and 148 g/cm2) bombarded by a 1 GeV proton beam. Release curves of several isotopes of the same element and production efficiency versus decay half-life are well fitted with the same set of parameters. Comparison of efficiencies for neutron-rich and neutron-deficient Cs isotopes enables separation of the contributions from the primary (p + 238U) and secondary (n + 238U) reactions to the production of neutron-rich Cs isotopes. A rather simple calculation of the neutron contribution describes these data fairly well. The FLUKA code describes the primary and secondary-reaction contributions to the Cs isotopes production efficiencies for different targets quite well. 相似文献
5.
L. Westgaard K. Aleklett G. Nyman E. Roeckl 《Zeitschrift für Physik A Hadrons and Nuclei》1975,275(2):127-144
Total decay energies have been measured for a number of neutron-deficient Rb and Cs isotopes, as well as for some neutron-rich isotopes of Fr and Ra. Mass separated sources were produced at the ISOLDE on-line separator at CERN. By applying two differentβ-γ coincidence methods,Q values or their lower limits were determined for76–78Rb,80Rb,121–124Cs,222Fr,224–226Fr,229Ra-229Ac. For many of these nuclei, the atomic mass excesses could be derived, allowing the comparison of masses of far unstable nuclei with predictions from mass formulae. The odd-odd nuclei76Rb and78Rb appear to be 1?1 1/2 MeV more strongly bound than expected from the systematics. 相似文献
6.
《Nuclear Physics A》1999,651(1):3-30
Direct mass measurements of short-lived Cs and Ba isotopes have been performed with the tandem Penning trap mass spectrometer ISOLTRAP installed at the on-line isotope separator ISOLDE at CERN. Typically, a mass resolving power of 600 000 and an accuracy of δm ≈ 13 keV have been obtained. The masses of 123,124,126Ba and 122mCs were measured for the first time. A least-squares adjustment has been performed and the experimental masses are compared with theoretical ones, particularly in the frame of a macroscopic-microscopic model. 相似文献
7.
A new version of integrated target-ion source unit (ionising target) has been developed for the on-line production of radioactive
single-charged ions. The target is able to withstand temperatures up to 2500 °C and acts also as an ion source of the surface and laser ionisation. Off-line and on-line experiments with the ionising target,
housing tantalum foils as a target material, have been carried out at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron)
facility. The off-line surface ionisation efficiency measured for stable atoms of Li, Rb and Cs was correspondingly 6% , 40%
and 55% at the target temperature of 2000 °C and 3-10% for atoms of rare-earth elements Sm, Eu, Tm and Yb at a temperature of 2200 °C. The off-line measured values of the ionisation efficiency for stable Gd and Eu atoms by the laser beam ionisation inside
the target were 1% and 7%, respectively. The radioactive beam intensities of neutron-deficient rare-earth nuclides from Eu
to Lu produced by the integrated target-ion source unit have been measured at a temperature of 2500 °C. The results of the integrated target-ion source unit use for on-line laser resonance ionisation spectroscopy study of neutron-deficient
Gd isotopes have been also presented. 相似文献
8.
The masses of over sixty short-lived Rb, Sr, Cs, Ba, Fr and Ra isotopes have been measured at the on-line mass separator ISOLDE at CERN/Geneva by determination of their cyclotron frequency in the tandem Penning trap system ISOLTRAP. Resolving powers exceedingm/m(FWHM)=106 and accuracies of typically m/m=10–7 could be achieved. ISOLTRAP can also act as an isomer separator, as proven for the cases of84Rb and78Rb. 相似文献
9.
D. Scarpa L. Biasetto S. Corradetti M. Manzolaro A. Andrighetto S. Carturan G. Prete P. Zanonato D. W. Stracener 《The European Physical Journal A - Hadrons and Nuclei》2011,47(3):32
In the framework of the R&D program for the SPES (Selective Production of Exotic Species) project of the Istituto Nazionale
di Fisica Nucleare (INFN), production yields of neutron-rich isotopes have been measured at the Holifield Radioactive Ion
Beam Facility (HRIBF, Oak Ridge National Laboratory, USA). This experiment makes use of the multi-foil SPES target prototype
composed of 7 uranium carbide discs, with excess of graphite (ratio C/U = 4 . 77 isotopes of medium mass (between 72 and 141amu), produced via proton-induced fission of uranium using a 40MeV proton
beam, have been collected and analyzed for the target heated at 2000 ° C target temperature. 相似文献
10.
G. Gwinner E. Gomez L. A. Orozco A. Perez Galvan D. Sheng Y. Zhao G. D. Sprouse J. A. Behr K. P. Jackson M. R. Pearson S. Aubin V. V. Flambaum 《Hyperfine Interactions》2006,172(1-3):45-51
Francium combines a heavy nucleus (Z = 87) with the simple atomic structure of alkalis and is a very promising candidate for precision tests of fundamental symmetries
such as atomic parity non-conservation measurements. Fr has no stable isotopes, and the ISAC radioactive beam facility at
TRIUMF, equipped with an actinide target, promises to provide record quantities of Fr atoms, up to 1010/s for some isotopes. We discuss our plans for a Fr on-line laser trapping facility at ISAC and experiments with samples of
cold Fr atoms. We outline our plans for a measurement of the nuclear anapole moment – a parity non-conserving, time-reversal
conserving moment that arises from weak interactions between nucleons – in a chain of Fr isotopes. Its measurement is a unique
probe for neutral weak interactions inside the nucleus.
相似文献
11.
J.M. Dauria J.W. Grüter E. Hagberg P.G. Hansen J.C. Hardy P. Hornsh?j B. Jonson S. Mattsson H.L. Ravn P. Tidemand-Petersson 《Nuclear Physics A》1978,301(3):397-410
Neutron-deficient caesium isotopes with mass numbers from 114 to 118 have been studied at the ISOLDE facility. Half-lives have been determined from counting of β-particles, β-delayed protons, and γ-rays. A short-lived isomer () in 116Cs has been observed and the new delayed-particle precursors 116Cs (protons and α-particles), 115Cs (protons), and 114Cs (protons and α-particles) have been identified. Coincidences between delayed particles and γ-rays have been measured for 118Cs (pγ and αγ) and 116Cs (pγ). A search for the possible proton-radioactive isotope 113Cs has been performed and an upper limit for its production yield is given. 相似文献
12.
Photographs of cross sections of an electron beam backscattered from a thin tungsten target have been obtained on a dosimetric film. The procession of images makes it possible to obtain the spatial distribution of backscattered particles. The angles of back reflection θbr of electron beams from foils have been measured. A 7.4-MeV microtron has been used as a source of electrons. The experiments have been performed with a tungsten foil 386 mg/cm2 (200 μm) thick and a tantalum foil 1328 mg/cm2 (800 μm) thick. Particles have been injected at an angle of α = 10° to the foil surface. The Monte Carlo simulation of the scattering of relativistic electrons incident on a planar target at small angles to its surface has been performed. The spatial and energy distributions of backscattered particle fluxes both transmitted through the target and reflected from it have been calculated. The dependences of fluxes on the direction of injection of particles and on the material and thickness of the target have been considered. 相似文献
13.
M.D. Di Rosa S.G. Crane J.J. Kitten W.A. Taylor D.J. Vieira X. Zhao 《Applied physics. B, Lasers and optics》2003,76(1):45-55
We report the first magneto-optical trapping of radioactive 135Cs and 137Cs and a promising means for detecting these isotopes at ultra-sensitive levels by coupling a magneto-optical trap (MOT) to
a mass separator. A sample containing both isotopes was placed in the source of a mass separator, ionized, mass-separated,
and implanted in a Zr foil within the trapping cell. After implantation, atoms were released from the foil by inductive heating
and then captured in a MOT that used large-diameter beams and a dry-film-coated cell to achieve high trapping efficiency.
Trapped-atom numbers in the case of either isotope ranged from 104 to 107, as determined from the MOT fluorescence signal. Over this trapped-atom range, the MOT fluorescence signal was found to increase
linearly with the number of atoms implanted in the foil and without isotopic bias to within 4%. In principle, this method
can then provide a measurement of the 137Cs/135Cs ratio accurate to within 4% through the direct ratio of MOT fluorescence signals. The fluorescence signal from stable 133Cs, when implanted and released from the foil, was suppressed relative to MOT signals by more than seven orders of magnitude
when the system was tuned to trap 135Cs or 137Cs. When combined with the isotopic selectivity of ≥105 for the mass separator, the overall suppression of 133Cs is expected to exceed 1012. At present our system delivers atoms from sample to MOT with an efficiency of 0.5%, has a trapped-atom detection limit of
4000 atoms, and achieves a sample-detection sensitivity of one million atoms.
Received: 23 August 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +1-505/667-0440, E-mail: mdd@lanl.gov 相似文献
14.
T. Bjørnstad H. -Å. Gustafsson B. Jonson O. C. Jonsson V. Lindfors S. Mattsson A. M. Poskanzer H. L. Ravn D. Schardt 《Zeitschrift für Physik A Hadrons and Nuclei》1981,303(3):227-233
Mass-separated ion beams of the alkali elements Na, K, and Fr, and of the element Tl, were produced by bombarding a uranium target with 600 MeV protons, 890 MeV3He2 +, and 936 MeV12C4 +. Isotopic production yields are reported. In the case of the12C beam, these are thick target yields. Absolute cross-sections for the proton beam data were deduced by normalizing the delay-time corrected yield curves to measured cross-sections. For products farthest away from stability, the3He2 + beam generally gives the highest yields. 相似文献
15.
Experimental β-decay energies for short-lived isotopes of tin, antimony and tellurium are presented. Mass-separated sources were produced at the on-line isotope separator OSIRIS. By applying β-γ coincidence methods, total β-decay energies have been determined for the following nuclides: 127?131Sn, 128, 130, 131, 134Sb and 134, 135Te. The atomic mass excess has been derived for these nuclei, and comparisons are made with mass formula predictions. 相似文献
16.
Benefiting from the continuous laser developments, resonance ionization can be applied for a variety of experiments on radioactive
isotopes, e.g. as a laser ion source for producing pure beams of short-lived isotopes at on-line facilities. In this paper
the application of a compact set-up for resonance ionization mass spectrometry for ultra-trace analysis of the long-lived
isotope Ca-41 is described. With this set-up a purely optical selectivity of 3×109 and an overall detection efficiency of 1.2(4)×10−5 are demonstrated. 相似文献
17.
G. T. Ewan E. Hagberg B. Jonson S. Mattsson P. Tidemand-Petersson 《Zeitschrift für Physik A Hadrons and Nuclei》1980,296(3):223-228
Neutron-deficient francium isotopes were produced by proton-induced spallation reactions and investigated by alpha spectroscopy following on-line mass separation. The new isotopes201, 202Fr were identified and their half-lives measured. An improved value for the half-life of203Fr was obtained. Alpha branching ratios were determined for198m, g, 199At. The derivation of the mass excess of202Fr and the systematics of alpha energies and reduced widths are discussed. 相似文献
18.
G. Lhersonneau P. Dendooven G. Canchel J. Huikari P. Jardin A. Jokinen V. Kolhinen C. Lau L. Lebreton A.C. Mueller A. Nieminen S. Nummela H. Penttilä K. Peräjärvi Z. Radivojevic V. Rubchenya M.-G. Saint-Laurent W.H. Trzaska D. Vakhtin J. Vervier A.C.C. Villari J.C. Wang J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):385-396
In the context of a parameter study conducted by several laboratories for future European radioactive beam facilities based
on fast-neutron induced fission, in particular for the SPIRAL-II project at GANIL, we have measured the yields of neutron-rich
isotopes in the mass range of 88 to 144. These nuclei were obtained as fission products of natural uranium bombarded by neutrons
of 20 MeV average energy emitted by a thick carbon target irradiated by 50 MeV deuterons. Yields have been measured using
on-line mass separation with the ion-guide method. Compared with proton-induced fission at 25 MeV the magnitude of cross-sections,
except for the symmetric region, is similar. Z-distributions of isobars have the same width, 0.7 charge units, but their maxima are shifted by about 0.8 charge units, favouring
production of the neutron-richer isobars. Our data allow calculations of absolute cross-sections for fission of natural uranium
induced by neutrons of about 20 MeV.
Received: 10 July 2000 / Accepted: 27 October 2000 相似文献
19.
The nuclear spin, , of a new isomer in 119Cs and the magnetic moment, μI = 3.92(5) n.m., of 120Cs have been determined in on-line ABMR experiments at the ISOLDE facility, CERN. The experimental data give evidence for strongly deformed nuclear shapes of the light cesium isotopes. 相似文献
20.
I. C. Girit G. D. Alton C. R. Bingham H. K. Carter M. L. Simpson J. D. Cole W. L. Croft J. H. Hamilton E. F. Jones P. M. Gore J. Kormicki H. Xie B. D. Kern K. S. Krane Y. S. Xu P. F. Mantica Jr. B. E. Zimmerman W. G. Nettles E. F. Zganjar M. O. Kortelahti W. B. Newbolt 《Hyperfine Interactions》1988,43(1-4):151-156
The UNISOR on-line nuclear orientation facility (UNISOR/NOF) consists of a3He−4He dilution refrigerator on line to the isotope separator. Nuclei are implanted directly into a target foil which is soldered
to the bottom accessed cold finger of the refrigerator. A 1.5 T superconducting magnet polarizes the ferromagnetic target
foils and determines the axis of symmetry. Up to eight gamma detectors can be positioned around the refrigerator, each 9 cm
from the target. A unique feature of this system is that the k=4 term in the directional distribution function can be directly
and unambigously deduced so that a single solution for the mixing ratio can be found. The first on-line experiment at this
facility reported here was a study of the decay of the191Hg and193Hg isotopes. 相似文献