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1.
U. Köster O. Arndt R. Catherall J. G. Correia B. Crepieux R. Eichler P. Fernier L. M. Fraile S. Hennrich K. Johnston S. Lukic J. Neuhausen B. S. Nara Singh B. Pfeiffer E. Siesling 《The European physical journal. Special topics》2007,150(1):293-296
The production of ISOL beams of hafnium is described.
Radioactive Hf isotopes were produced at ISOLDE by 1.4 GeV proton-induced spallation
in Ta and W foils. Chemical evaporation in form of HfF4 and mass separation in the
molecular sideband HfF3+ after electron impact ionization provided intense
and pure beams.
Beams of 158-185Hf and short-lived isomers down to 1.1 s 177mHf were
observed, but the method could be extended to reach even more exotic isotopes:
down to about 154Hf (N=82) on the neutron-deficient side and up to
neutron-rich 188Hf. 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.
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
4.
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
5.
Summary We calculate several features in the dynamical behaviour of the reactions O(3P)+XY→OX+Y (XY=Br2, BrCl) using the quasi-classical trajectory method. The results are compared to analogous results for the reactions O(3P)+Cl2, I2. The similarities observed in this homologous series of reactions indicate that the dynamics are influenced to a significant
degree by the long-range repulsive forces between the reactants. 相似文献
6.
D.J. Morrissey 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):105-108
The physics opportunities made possible by beams of rare isotopes are among the richest available in nuclear science. The
rare-isotope accelerator (RIA) now under development is an innovative accelerator that will define the state of the art for
all such facilities. A novel aspect of the RIA project is the conversion of the most intense high-energy heavy-ion beams into
both fast and reaccelerated exotic beams. Along with target fragmentation in next-generation high-power ISOL targets, RIA
will use projectile fragmentation in a high-energy separator/gas-filled ion collector system to provide an extensive range
of thermalized ions for reacceleration. In addition, a second high-energy separator will provide the same or larger range
of ions for high-energy experiments. A brief overview of the RIA accelerator concept, the layout of the facility, and production
techniques will be given along with information on the present R&D efforts in gaseous-ion collection.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: morrissey@nscl.msu.edu 相似文献
7.
O.V. Bychuk B. O'Shaughnessy N.J. Turro 《The European physical journal. E, Soft matter》2001,4(3):281-291
We propose and theoretically study an experiment designed to measure short-time polymer reaction kinetics in melts or dilute
solutions. The photolysis of groups centrally located along chain backbones, one group per chain, creates pairs of spatially
highly correlated macroradicals. We calculate time-dependent rate coefficients κ(t) governing their first-order recombination kinetics, which are novel on account of the far-from-equilibrium initial conditions.
In dilute solutions (good solvents) reaction kinetics are intrinsically weak, despite the highly reactive radical groups involved.
This leads to a generalised mean-field kinetics in which the rate of radical density decay - ∼S(t), where S(t) ∼t
- (1 + g/3) is the equilibrium return probability for 2 reactive groups, given initial contact. Here g≈ 0.27 is the correlation hole exponent for self-avoiding chain ends. For times beyond the longest coil relaxation time τ,
- ∼S(t) remains true, but center of gravity coil diffusion takes over with rms displacement of reactive groups x(t) ∼t
1/2 and S(t) ∼ 1/x
3(t). At the shortest times ( t
10-6s), recombination is inhibited due to spin selection rules and we find ∼tS(t). In melts, kinetics are intrinsically diffusion-controlled, leading to entirely different rate laws. During the regime limited
by spin selection rules, the density of radicals decays linearly, n(0) - n(t) ∼t. At longer times the standard result - ∼d
3(t)/d (for randomly distributed ends) is replaced by ∼d2x
3(t)/d
2 for these correlated initial conditions. The long-time behavior, t > τ, has the same scaling form in time as for dilute solutions.
Received 18 May 2000 相似文献
8.
P. Campbell A. Nieminen J. Billowes P. Dendooven K.T. Flanagan D.H. Forest Yu.P. Gangrsky J.A.R. Griffith J. Huikari A. Jokinen I.D. Moore R. Moore H.L. Thayer G. Tungate S.G. Zemlyanoi J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):45-48
A new RFQ ion-beam cooler and buncher, installed after the mass-separating magnet of the ion guide isotope separator, IGISOL,
JYFL, has dramatically increased the scope of on-line laser spectroscopy at this facility. The device, operated in a bunching
mode, has permitted new measurements on short-lived radionuclei in the Ti, Zr and Hf chains at a sensitivity two orders of
magnitude greater than that previously achieved. The device has also opened new prospects for laser-based nuclear spectroscopy
at the facility, particularly collinear resonance ionisation spectroscopy.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: pc@mags.ph.man.ac.uk 相似文献
9.
F. Ibrahim J. Obert O. Bajeat J.M. Buhour D. Carminati F. Clapier C. Donzaud M. Ducourtieux J.M. Dufour S. Essabaa S. Galès D. Guillemaud-Mueller F. Hosni O. Hubert A. Joinet U. Köster C. Lau H. Lefort G. Le Scornet J. Lettry A.C. Mueller M. Mirea N. Pauwels O. Perru J.C. Potier J. Proust F. Pougheon H. Ravn L. Rinolfi G. Rossat H. Safa M.G. Saint Laurent M. Santana-Leitner O. Sorlin D. Verney 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):357-360
A PARRNe 1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) aimed at the production of neutron-rich radioactive
noble gases produced by photofission has been performed at CERN. The LEP Pre-Injector (LPI) has been used to deliver a 50
MeV electron beam. The results obtained show clearly that the use of an electron beam to produce neutron-rich fission fragments
for futur RNB facilities is an option that should not be neglected.
Received: 20 July 2001 / Accepted: 5 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: ibrahim@ipno.in2p3.fr
Communicated by D. Guerreau 相似文献
10.
M. Gaelens J. Andrzejewski J. Camps P. Decrock M. Huyse K. Kruglov W.F. Mueller A. Piechaczek N. Severijns J. Szerypo G. Vancraeynest P. Van Duppen J. Wauters 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):413-420
A high-precision measurement of the 14O half-life has been performed using a mass-separated radioactive beam in combination with a germanium detector set-up. This
is the first 14O half-life measurement with a contamination-free source. The final result of 70.560 ± 0.049 seconds is in agreement with
the generally adopted mean value.
Received: 5 April 2001 / Accepted: 6 August 2001 相似文献
11.
R.?Wilfinger J.?Lettry the EURISOL?Task Workgroup 《The European physical journal. Special topics》2007,150(1):379-382
EURISOL foil-targets have to withstand a primary proton
beam of 1 GeV kinetic energy and up to 100 μA
beam current. These foil targets will be based on previous
high-power target concepts, i.e. the RIST target [J.R.J. Bennett et al.,
Nucl. Instrum. Meth. Phys. Res. B 126, 117 (1997)]
or high power targets used at
TRIUMF [P. Bricault et al.,
Nucl. Instrum. Meth. Phys. Res. B 204, 319 (2003), M. Dombsky et al.,
Nucl. Instrum. Meth. Phys. Res. B 204, 191 (2003)].
A single target unit is capable of dissipating up to 25 kW,
hence, several target units can be merged together by individual
transfer lines to one common ion source. The single target units
will be irradiated by a proton beam in a time sharing mode to
distribute the primary proton beam current to the individual
target units. In this feasibility study the necessary properties
of high-power foil targets are discussed and the requirements to
design a foil target according to the proton beam parameters
[CITE] for the future EURISOL facility
are given. 相似文献
12.
G. A. Souliotis A. L. Keksis B. C. Stein M. Veselsky M. Jandel D. V. Shetty S. N. Soisson S. Wuenschel S. J. Yennello 《The European physical journal. Special topics》2007,150(1):325-327
Recent efforts to produce and separate neutron-rich rare
isotopes in peripheral collisions below the Fermi energy are
presented. The experiments have been performed at the Cyclotron
Institute of Texas A&M University employing beams from the K500
Superconducting Cyclotron. Two magnetic separators were used: the
MARS recoil separator and the Superconducting Solenoid Line (BigSol
Line). An enhanced production of neutron-rich nuclides in comparison
with high-energy fragmentation mechanisms has been observed and
attributed to the role of the N/Z and the nuclear periphery of the
target. From a practical viewpoint, these reactions below or around
the Fermi energy offer a novel way to access very neutron-rich rare
isotopes. The experience obtained in the production of rare isotope
beams (RIB) below the Fermi energy will be exploited in the ongoing
RIB upgrade of the Cyclotron Institute that will involve production,
stopping and reacceleration of rare isotopes. 相似文献
13.
D. Guerreau 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):263-266
During the last ten years, the cooperation in Nuclear Physics between the different European countries has significantly increased,
in particular through extensive discussions initiated by NuPECC, the Nuclear Physics European Collaboration Committee. In
this context, perspectives in physics with radioactive beams have been reviewed and a high priority has been given to the
developments of performing facilities in Europe including both in-flight and ISOL facilities. In this presentation, the main
challenges are recalled and the various existing national and transnational projects are reviewed as well as the accompanying
research and development programs. A special attention is given to the EURISOL project, a European program aiming at a preliminary
design study of a second-generation European ISOL radioactive beam facility.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
14.
Ch. E. Düllmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):75-80
In recent years, the concept of physical preseparation of single atoms was
introduced into the field of transactinide chemistry. In this approach, the
transactinide element of interest is isolated in a physical recoil separator
and then extracted from this machine. The beam as well as the unwanted
reaction products are strongly suppressed, allowing for the investigation of
new chemical systems that were not accessible before.
The most important aspects of the technique are discussed and the advantages
for chemistry experiments with transactinides are presented, using some of
the chemical studies that were performed with preseparated isotopes as
examples. 相似文献
15.
M. Re G. Cuttone L. Celona F. Chines E. Messina D. Rizzo F. Tudisco V. Scuderi 《The European physical journal. Special topics》2007,150(1):303-306
The EXCYT facility at the INFN-LNS is based on a K-800
superconducting cyclotron delivering stable ion beams on a Target
Ion Source (TIS) assembly to produce the required nuclear species,
and on a 15 MV Tandem for post-accelerating the radioactive beams.
For some ion beams such as for Li, the extraction efficiency from
the TIS is higher when obtained by positive ionisation, while the
injection into the Tandem is possible only after a charge exchange
to obtain negative ions. In this work we present the procedures
together with the results of the production of 6,7,8,9Li beams extracted at EXCYT during the last year. The
production of the radioactive elements was performed by sending a
13C4+ primary beam of 45 MeV/u on a graphite target. The
ionisation of the production species was achieved by a tungsten
positive surface ioniser. The Li+ has been extracted from TIS
at different energies to cross-check the transmission and the
charge exchange efficiency. To perform the conversion from
positive to negative ions we employed a Charge Exchange Cell (CEC)
containing Cs vapours. The Li beam interacts with the latter in a
two-step reaction, thus converting its charge from +1 to –1. The
CEC was already characterised during off-line tests; the results
obtained at EXCYT confirmed both the isotopic shift effect and the
efficiency values at several given extraction energies. Future
improvements of the TIS and the CEC are discussed. 相似文献
16.
W. Christen U. Even 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):283-286
Size-selected, protonated water cluster cations
(H2O)nH+,
4 n 32, are scattered at
normal incidence from the surface of a diamond-coated silicon
wafer at collision energies 0 E
coll 500 eV. The size distribution of
collision-induced fragment-ions and the ion yield of scattered
particles are analyzed, using a secondary time-of-flight mass
spectrometer, as a function of the cluster size,
n, and the collision energy,
E
coll. Even at low impact energies only
very small fragment-ions can be detected, with a maximum
fragment size of 35% of the colliding parent cluster ions. For
clusters consisting of more than 10 molecules, the protonated
water dimer
(H2O)2H+
becomes the predominant fragment-ion. The total charge survival
yield obeys a nonlinear increase with cluster size; for the
largest clusters investigated, more than 35% of the impacting
ions survive the surface collision in the cationic charge state. 相似文献
17.
J.A. Nolen 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):255-261
There are several nuclear physics laboratories in North America that have on-going research using energetic and stopped radioactive
beams. These include the large ISOL-type programs ISAC at TRIUMF and HRIBF at Oak Ridge and the in-flight fragmentation program
at the NSCL of Michigan State University. There are also smaller, more specialized, programs using a variety of techniques
at the 88-inch cyclotron of Berkeley, ATLAS at Argonne, the Cyclotron Institute of Texas A&M University, the Nuclear Structure
Laboratory at Notre Dame University, and the Nuclear Structure Laboratory at SUNY/Stony Brook. There are also three projects
on the horizon in North America for new capabilities in both the near term and more distant future. The intensities of the
in-flight fragment beams at the NSCL will be increased dramatically very soon as the Coupled Cyclotron Project will be completed
and commissioned for research by mid-2001. A new project, ISAC-II, has been approved in Canada. For the longer term, the United
States is considering construction of a major new facility, the Rare Isotope Accelerator (RIA), which would have a very high-intensity
heavy-ion driver linac. The RIA facility is proposed to utilize both ISOL and in-flight production mechanisms.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
18.
K. Kruglov A. Andreyev B. Bruyneel S. Dean S. Franchoo M. Górska K. Helariutta M. Huyse Yu. Kudryavtsev W.F. Mueller N.V.S.V. Prasad R. Raabe K.-H. Schmidt P. Van Duppen J. Van Roosbroeck K. Van de Vel L. Weissman 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):365-370
Heavy 65-70Co, 68-74Ni, 70-76Cu and 74-81Ga isotopes were produced at the LISOL facility by means of 30 MeV proton-induced fission of 238U. Production rates were deduced and compared to two types of cross-section calculations: the empirical model (V. Rubchenya,
private communication) and the PROFI code. Comparison with experimental data favors the latter model. Yields using different
beam-target combinations and different energies are calculated and discussed.
Received: 11 February 2002 / Accepted: 26 April 2002 相似文献
19.
S. Kubono Y. Yanagisawa T. Teranishi S. Kato Y. Kishida S. Michimasa Y. Ohshiro S. Shimoura K. Ue S. Watanabe N. Yamazaki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):217-220
An in-flight RIB separator at low energies, which is the first extensive separator at low energies, called CRIB, is just under
construction at CNS. This consists of a double-achromatic magnetic separator, a window-less gas target, and a Wien filter.
Some characteristics of the CRIB are described. Possible experimental plans are also discussed in our nuclear astrophysics
project for the study of the explosive hydrogen burning process, especially on the onset mechanism.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
20.
W. Christen U. Even 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):87-90
This contribution addresses the inelastic interaction of positively charged molecular cluster ions with a solid surface at
kinetic energies up to 30 eV/molecule. We report experimental results on the scattering of mass-selected, protonated methanol
cluster cations (CH3OH)nH+, n = 4-32, off a diamond-coated silicon surface. In particular we provide fragment size distributions of methanol cluster ions
following their impact on the target, as well as surface-induced neutralization probabilities of methanol cluster ions as
a function of the size and the kinetic energy of the parent clusters.
Received 30 November 2000 相似文献