共查询到20条相似文献,搜索用时 578 毫秒
1.
C. Gund H. Bauer J. Cub A. Dietrich T. Härtlein H. Lenske D. Pansegrau A. Richter H. Scheit G. Schrieder D. Schwalm 《The European Physical Journal A - Hadrons and Nuclei》2001,10(1):85-95
As a tool for studying the structure of nuclei far off stability the technique of γ-ray spectroscopy after low-energy single-nucleon
transfer reactions with radioactive nuclear beams in inverse kinematics was investigated. Modules of the MINIBALL germanium
array and a thin position-sensitive parallel plate avalanche counter (PPAC) to be employed in future experiments at REX-ISOLDE
were used in a test experiment performed with a stable 36S beam on deuteron and 9Be targets. It is demonstrated that the Doppler broadening of γ lines detected by the MINIBALL modules is considerably reduced
by exploiting their segmentation, and that for beam intensities up to 106 particles/s the PPAC positioned around zero degrees with respect to the beam axis allows not only to significantly reduce
the γ background by requiring coincidences with the transfer products but also to control the beam and its intensity by single
particle counting. The predicted large neutron pickup cross-sections of neutron-rich light nuclei on 2H and 9Be targets at REX-ISOLDE energies of 2.2 MeV .
A are confirmed.
Received: 9 October 2000 / Accepted: 28 January 2001 相似文献
2.
D. A. Artemenkov V. Bradnova M. M. Chernyavsky L. A. Goncharova M. Haiduc N. A. Kachalova S. P. Kharlamov A. D. Kovalenko A. I. Malakhov A. A. Moiseenko G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova V. R. Sarkisyan R. Stanoeva T. V. Shchedrina S. Vokál A. Vokálová P. I. Zarubin I. G. Zarubina 《Physics of Atomic Nuclei》2008,71(9):1565-1571
The technique of nuclear track emulsions is used to explore the fragmentation of light relativistic nuclei down to the most
peripheral interactions: nuclear “white” stars. A complete pattern of the relativistic dissociation of a 8B nucleus with target
fragment accompaniment is presented. Relativistic dissociation 9Be → 2α is explored using significant statistics, and a relative contribution of 8Be decays from 0+ and 2+ states is established. Target fragment accompaniments are shown for relativistic fragmentation 14N → 3He +H and 22Ne → 5He. The leading role of the electromagnetic dissociation on heavy nuclei with respect to breakups on target protons
is demonstrated in all these cases. It is possible to conclude that the peripheral dissociation of relativistic nuclei in
nuclear track emulsion is a unique tool to study many-body systems composed of the lightest nuclei and nucleons in the energy
scale relevant for nuclear astrophysics.
The text was submitted by the authors in English. 相似文献
3.
V.B. Gavrikov V.P. Likhachev J.D.T. Arruda-Neto A.L. Bonini 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):487-493
Differential and integral features of incoherent X-radiation, induced by relativistic electrons in crystals, are studied for
observation angles θγ several times greater than γ-1, where γ is the projectile Lorentz factor. The existence of sharp maxima and a minimum of the five-folded incoherent differential
cross-section as a function of the final electron angles, and a dip minimum when the cross-section is taken as a function
of the photon energies, is demonstrated. At near backward observation angles the three-folded cross-section shows a maximum
in the region of several keV photon energies. The obtained results allow us to optimize the conditions for coincidence experiments,
minimizing the incoherent contribution to the total radiation yield, and helping to analyse results of finite-size detector
experiments with crystal targets.
Received: 2 July 2001 / Accepted: 26 November 2001 相似文献
4.
Hartmut Backe 《Hyperfine Interactions》2006,171(1-3):93-107
Unique spectroscopic possibilities open up if a laser beam interacts with relativistic lithium-like ions stored in the heavy
ion ring accelerator SIS300 at the future Facility for Antiproton and Ion Research FAIR in Darmstadt, Germany. At a relativistic
factor γ = 36 the 2P1/2 level can be excited from the 2S1/2 ground state for any element with frequency doubled dye-lasers in collinear geometry. Precise transition energy measurements
can be performed if the fluorescence photons, boosted in forward direction into the X-ray region, are energetically analyzed
with a single crystal monochromator. The hyperfine structure can be investigated at the 2P1/2−2S1/2 transition for all elements and at the 2P3/2−2S1/2 transition for elements with Z≤50. Isotope shifts and nuclear moments can be measured with unprecedented precision, in principle even for only a few stored
radioactive species with known nuclear spin. A superior relative line width in the order of 5·10−7 may be feasible after laser cooling, and even polarized external beams may be prepared by optical pumping. 相似文献
5.
We study the production of radioisotopes for nuclear medicine in (γ,xn+yp) photonuclear reactions or (γ,γ′) photoexcitation reactions with high-flux [(1013–1015)γ/s], small diameter ∼(100 μm)2 and small bandwidth (ΔE/E≈10−3–10−4) γ beams produced by Compton back-scattering of laser light from relativistic brilliant electron beams. We compare them to (ion,xn+yp) reactions with (ion = p,d,α) from particle accelerators like cyclotrons and (n,γ) or (n,f) reactions from nuclear reactors. For photonuclear reactions with a narrow γ-beam the energy deposition in the target can be managed by using a stack of thin target foils or wires, hence avoiding direct
stopping of the Compton and pair electrons (positrons). However, for ions with a strong atomic stopping only a fraction of
less than 10−2 leads to nuclear reactions resulting in a target heating, which is at least 105 times larger per produced radioactive ion and often limits the achievable activity. In photonuclear reactions the well defined
initial excitation energy of the compound nucleus leads to a small number of reaction channels and enables new combinations
of target isotope and final radioisotope. The narrow bandwidth γ excitation may make use of the fine structure of the Pygmy Dipole Resonance (PDR) or fluctuations in γ-width leading to increased cross sections. Within a rather short period compared to the isotopic half-life, a target area
of the order of (100 μm)2 can be highly transmuted, resulting in a very high specific activity. (γ,γ′) isomer production via specially selected γ cascades allows to produce high specific activity in multiple excitations, where no back-pumping of the isomer to the ground
state occurs. We discuss in detail many specific radioisotopes for diagnostics and therapy applications. Photonuclear reactions
with γ-beams allow to produce certain radioisotopes, e.g. 47Sc, 44Ti, 67Cu, 103Pd, 117m
Sn, 169Er, 195m
Pt or 225Ac, with higher specific activity and/or more economically than with classical methods. This will open the door for completely
new clinical applications of radioisotopes. For example 195m
Pt could be used to verify the patient’s response to chemotherapy with platinum compounds before a complete treatment is performed.
Also innovative isotopes like 47Sc, 67Cu and 225Ac could be produced for the first time in sufficient quantities for large-scale application in targeted radionuclide therapy. 相似文献
6.
A. V. Glushkov O. Yu. Khetselius S. V. Malinovskaya 《The European physical journal. Special topics》2008,160(1):195-204
A consistent QED perturbation theory approach is applied to
calculation of the electron-nuclear γ-transition spectrum
of nucleus in the multicharged ion. The intensities of satellites
are defined within the relativistic version of the energy approach
(Gell-Mann and Low S-matrix formalism). As example, the nuclear
transition in the isotope
with the energy 14.41 keV is considered. The
results of the relativistic calculation for the electron-nuclear
γ-transition spectrum (a set of electron satellites) of the
nucleus in a multicharged atomic ion FeXIX are presented. The
possible experiments for observation of the new effect in the
thermalized plasma of the O-like ions are discussed. A consistent
quantum approach to calculation of the electron-nuclear γ
transition spectrum (a set of vibration-rotational satellites in a
molecule) of nucleus in a molecule is proposed and based on the
Dunham model potential approximation for potential curves of the
diatomic molecules. Model proposed generelizes the well known
Letokhov-Minogin model. The estimates are made for
vibration-rotation-nuclear transition probabilities in a case of
the emission and absorption spectrum of nucleus 127I
(E(0)γ=203 keV) in the molecule of H127I. 相似文献
7.
R. Lednicky 《Physics of Atomic Nuclei》2008,71(9):1514-1517
One of the basic facilities at the Joint Institute for Nuclear Research (JINR) in Dubna is the 6 A GeV Nuclotron, which has replaced the old weak focusing 10-GeV proton accelerator Synchrophasotron. The first relativistic
nuclear beams with the energy of 4.2 A GeV were obtained at the Synchrophasotron in 1971. Since that time, relativistic nuclear physics has been one of the main
directions of the JINR research program. In the coming years, the new JINR flagship program assumes the experimental study
of hot and dense strongly interacting QCD matter at the new JINR facility. This goal is proposed to be reached by (i) development
of the existing Nuclotron accelerator facility as a basis for generation of intense beams over atomic mass range from protons
to uranium and light polarized ions, (ii) design and construction of the Nuclotron-based heavy Ion Collider fAcility (NICA)
with the maximum nucleon-nucleon center-of-mass collision energy of √s
NN
= 9 GeV and averaged luminosity 1027 cm−2 s−1, and (iii) design and construction of the Multipurpose Particle Detector (MPD) at intersecting beams. Realization of the
project will lead to unique conditions for research activity of the world community. The NICA energy region is of major interest
because the highest nuclear (baryonic) density under laboratory conditions can be reached there. Generation of intense polarized
light nuclear beams aimed at investigation of polarization phenomena at the Nuclotron is foreseen.
The text was submitted by the author in English. 相似文献
8.
Lepton-pair production from deep inelastic scatteringin peripheral relativistic heavy ion collisions
U. Dreyer T. Baier K. Hencken D. Trautmann 《The European Physical Journal C - Particles and Fields》2006,45(3):783-795
We calculate the inelastic electron- and muon-pair production in peripheral relativistic heavy ion collisions in the region
of large Q2 of one of the photons. This offers a possibility to study the quark distribution functions in ions in "ultraperipheral heavy
ion collisions". The calculations are compared with those making use of the equivalent photon and the equivalent lepton approximation.
We compare the results for Pb-Pb and Pb-p collisions at RHIC (γ ≈ 100) and LHC (γ ≈ 3000) energies. Furthermore we include nuclear modifications to the parton distribution
functions in our calculations to study their effect on the cross sections. 相似文献
9.
V. Bradnova M. M. Chernyavsky L. Just S. P. Kharlamov A. D. Kovalenko M. Haiduc K. A. Kotel’nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov S. Vokal P. I. Zarubin 《Physics of Atomic Nuclei》2003,66(9):1646-1650
A physical program of irradiation of emulsions in beams of relativistic nuclei named the BECQUEREL Project is reviewed. It is destined to study in detail the processes of relativistic fragmentation of light radioactive and stable nuclei. The expected results would make it possible to answer some topical questions concerning the cluster structure of light nuclei. Owing to the best spatial resolution, the nuclear emulsions would enable one to obtain unique and evident results. The most important irradiations will be performed in the secondary beams of He, Be, B, C, and N radioactive nuclei formed on the basis of JINR Nuclotron beams of stable nuclei. We present results on the charged state topology of relativistic fragmentation of the 10B nucleus at low energy-momentum transfers as the first step of the research. 相似文献
10.
R. Brandt V. A. Ditlov K. K. Dwivedi W. Ensinger E. Ganssauge Guo Shi-Lun M. Haiduc S. R. Hashemi-Nezhad H. A. Khan M. I. Krivopustov R. Odoj E. A. Pozharova V. A. Smirnitzki A. N. Sosnin W. Westmeier M. Zamani-Valasiadou 《Physics of Particles and Nuclei》2008,39(2):259-285
Interactions of relativistic heavy ions with total energies above 30 GeV in thick Cu and Pb targets (≥ 2 cm) have been studied
with various techniques. Radiochemical irradiation experiments using thick Cu targets, both in a compact form or as diluted
“2π-Cu targets” have been carried out with several relativistic heavy ions, such as 44 GeV 12C (JINR, Dubna, Russia) and 72 GeV 40Ar (LBL, Berkeley, USA). Neutron measuring experiments using thick targets irradiated with various relativistic heavy ions
up to 44 GeV 12C have been performed at the JINR. In addition, the number of “black prongs” in nuclear interactions (due to protons with
energies less than 30 MeV and emitted from the target-like interaction partner at rest) produced with 72 GeV 22Ne ions in nuclear emulsion plates has been measured in the first nuclear interaction of the primary 22Ne ion and in the following second nuclear interaction of the secondary heavy (Z > 1) ion. Some essential results have been obtained. (1) Spallation products produced by relativistic secondary fragments
in interactions ([44 GeV 12C or 72 GeV 40Ar] + Cu) within thick copper yield fewer products close to the target and many more products far away from the target as
compared to primary beam interactions. This applies also to secondary particles emitted into large angles (Θ > 10°). (2) The
neutron production of 44 GeV 12C within thick Cu and Pb targets is beyond the estimated yield as based on experiments with 12 GeV 12C. These rather independent experimental results cannot be understood within well-accepted nuclear reaction models. They appear
to present unresolved problems.
The text was submitted by the authors in English. 相似文献
11.
J. Wrzesiński K.H. Maier R. Broda B. Fornal W. Królas T. Pawłat D. Bazzacco S. Lunardi C. Rossi Alvarez G. de Angelis A. Gadea J. Gerl M. Rejmund 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):259-265
High-spin states in 208Pb have been studied by γ-ray-spectroscopy methods in deep inelastic reactions induced by beams of 208Pb, 136Xe and 76Ge beams on a thick 208Pb target. The 11+
2 state and new γ-transitions between the one-particle one-hole states of highest spin have been found and electromagnetic
matrix elements verified. High-spin states of two-particle two-hole structure have been detected for the first time. The results
are compared to shell model calculations with realistic interactions in the complete Kuo-Herling space.
Received: 31 October 2000 / Accepted: 26 March 2001 相似文献
12.
S. Pietri P. H. Rega Zs. Podolyák A. Jungclaus M. Pfützner D. Rudolph A. B. Garnsworthy S. J. Steer R. Hoischen M. Górska J. Gerl H. J. Wollersheim I. Kojouharov H. Schaffner J. Grębosz F. Becker P. Bednarczyk L. Caceres P. Doornenbal H. Geissel A. Kelic N. Kurz F. Montes W. Prokopowicz T. Saito S. Tashenov E. Werner-Malento W. Gelletly 《The European physical journal. Special topics》2007,150(1):319-320
The RISING (Rare ISotope INvestigations at GSI) project constitutes a major
pan-european initiative to study nuclear structure in exotic nuclei.
A brief outline of the technical details specific to studies of isomeric decays
following relativistic projectile fragmentation reactions is presented. 相似文献
13.
Z.G. Gan Z. Qin J.S. Guo L.J. Shi H.Y. Liu T.R. Guo X.G. Lei R.C. Ma W.X. Huang S.G. Yuan X.Q. Zhang G.M. Jin 《The European Physical Journal A - Hadrons and Nuclei》1999,6(1):59-61
The decay of 131Pm has been investigated by means of γ-ray spectroscopy. The 131Pm nuclei were produced by fusion-evaporation reaction of 106Cd(32S,3p4n) at the beam energy of 170 MeV. A helium-jet technique and a tape transport system were used to collect the activities
and transfer them to a detecting position for X and γ rays measurement. Two γ rays of 185.0 and 220.0 keV were unambiguously
identified to follow the β+ decay of 131Pm by results of X-γ and γ–γ coincidence. A growth-decay feature of the decay curve for 87.8 keV γ-ray of 131Nd confirmed the production of 131Pm nuclei. The half-life of 131Pm was measured to be 6.3 ± 0.8 s. A partial decay scheme of 131Pm is proposed on the basis of X-γ and γ–γ coincidence data in this experiment and the known structure information deduced
from in-beam experiments of the daughter nucleus 131Nd.
Received: 11 January 1999 / Revised version: 20 May 1999 相似文献
14.
B. Schlitt K. Beckert T. Beha H. Eickhoff B. Franzke H. Geissel H. Irnich H. C. Jung T. F. Kerscher O. Klepper K. E. G. Löbner G. Münzenberg F. Nolden Y. Novikov T. Radon H. Reich A. Schwinn M. Steck K. Sümmerer T. Winkler H. Wollnik 《Hyperfine Interactions》1996,99(1):117-125
Schottky mass spectrometry is a novel method of precision nuclear mass spectrometry based on the measurement of the revolution frequencies of cooled ions in storage rings performed by non-destructive frequency analysis of the beam noise, the well-established Schottky diagnosis technique. The method was applied for the first time at the Experimental Storage Ring ESR at GSI observing electron cooled highly charged ions up to bare nuclei at relativistic energies around several hundred MeV/u. To demonstrate the performance and feasibility of the method at the ESR, experimental tests have been carried out using beams of nuclear fragments produced in the ring itself by the interaction of different primary beams with the internal gas jet target. Futhermore, first Schottky mass measurements of secondary nuclear beams produced by projectile fragmentation of Au and Bi primary beams in a thick Be-target were carried out in order to determine the masses for numerous heavy neutron deficient nuclei which had not been measured before. Relative accuracies for the measured mass values in the order of 1×10–6 and below can be achieved. The method is briefly discussed and some early results are presented. 相似文献
15.
M. Koll R. Ricken D. Merten B.C. Metsch H.R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):73-94
We present new results of a relativistic quark model based on the Bethe-Salpeter equation in its instantaneous approximation.
Assuming a linearly rising confinement potential with an appropriate spinorial structure in Dirac space and adopting a residual
interaction based on instanton effects, we can compute masses of the light mesons up to highest observed angular momenta with
a natural solution of the U
A(1) problem. The calculated ground states masses and the radial excitations describe the experimental results well. In this
paper, we will also discuss our results concerning numerous meson decay properties. For processes like π+/K
+↦e
+υeγ and 0-↦γγ at various photon virtualities, we find a good agreement with experimental data. We will also comment on the form factors
of the K
?3 decay and on the decay constants of the π, K and η mesons. For the sake of completeness, we will furthermore present the electromagnetic form factors of the charged π
and K mesons as well as a comparison of the radiative meson decay widths with the most recent experimental data.
Received: 28 August 2000 / Accepted: 12 September 2000 相似文献
16.
M. Kaskulov E. Hernandez E. Oset 《The European Physical Journal A - Hadrons and Nuclei》2007,31(2):245-254
With the aim of extracting information on the shift of the ω mass in the nuclear medium we analyze data obtained at ELSA from
where claims for evidence of a mass shift of the ω have been made. We develop a Monte Carlo simulation code which takes into
account the possible reactions in the experimental set-up of (γA → π0γX) in the vicinity of the ω production region with subsequent ω → π0γ decay. We compare our results with experiment for the distribution of π0γ invariant masses and conclude that the distribution is compatible with an enlarged ω width of about 90MeV at nuclear-matter
density and no shift in the mass. This change in the width would be compatible with the preliminary results obtained from
the transparency ratio in the A-dependence of ω production. The discrepancy of the present conclusions with former claims of an evidence for a shift of the
ω mass stems from a different choice of background which is discussed in the paper. 相似文献
17.
N. A. Demekhina A. A. Kulko Yu. E. Penionzhkevich N. K. Skobelev T. V. Chuvilskaya A. A. Shirokova 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(11):1466-1468
The excitation functions and isomeric cross-section ratios obtained at irradiation of 197Au by a 6He-ion beams with energies from 15 to 60 MeV has been analyzed. The EMPIRE-2.18 code was used in the calculations. The cross
sections of the isomeric and ground nuclear state production were calculated taking into account the probabilities of occupation
of the final nucleus discrete levels in cascades of γ transitions. 相似文献
18.
T. Glasmacher B.V. Pritychenko P.D. Cottle R.W. Ibbotson K.W. Kemper H. Scheit 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):59-62
Projectile fragmentation provides radioactive beams at intermediate velocities (v/c = 0.3-0.5) by physical means of fragment separation. With the development of position-sensitive photon detectors it has become
possible to measure the energies and directions of photons emitted in-flight from such fast-moving exotic beams. This allows
the reconstruction of the photons' energies emitted from an exotic projectile with high accuracy. It can be advantageous to
employ photon detection in experiments with exotic beams since photons can traverse matter easily and their attenuation can
be calculated. Experiments with standard luminosities can be carried out at intermediate beam energies with thick secondary
targets (order of g/cm2) and very low incident beam rates (order of particle/s or less). Experimental success in this field is strongly correlated
with the development of photon detectors such as position-sensitive scintillation detectors or segmented germanium detectors.
In-beam gamma-ray spectroscopy of fast exotic beams has been successfully used at all projectile fragmentation facilities
in intermediate-energy heavy-ion inelastic scattering experiments, knockout reactions and fragmentation reactions. Here, we
focus on experimental results for neutron-rich exotic nuclei in the π(sd )-shell. Measurements and detector developments carried out at the NSCL at Michigan State University during the last four
years are discussed.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
19.
An emulsion chamber was used to study the characteristics of high energy nuclear interactions from the production spectra
ofγ-rays. The emulsion chamber, which comprised of two parts, namely the detector and the graphite producer unit, was exposed
to cosmic rays for about 7 hr at an atmospheric depth of 10 g cm−2 at Hyderabad (geomagnetic latitude 7·6°N). 720 electromagnetic cascades due toγ-rays were recorded in the detector. These cascades were classified into three groups; (a)γ-rays from nuclear interactions in the detector (b)γ-rays from nuclear interactions in the producer unit and (c)γ-rays of atmospheric origin. The energies of the cascades were determined using photometric method. The spectra ofγ-rays from groups (a) and (c) were determined and compared with similar spectra obtained at greater atmospheric depths. The
spectra were found to obey a power law. The spectrum ofγ-rays of atmospheric origin was found to steepen at high energies,E
r>2200 GeV. 相似文献
20.
D. E. Murnick 《Hyperfine Interactions》1985,24(1-4):143-157
Hyperfine interaction techniques have historically been applied to produce polarized nuclei. The use of optical pumping with
tunable lasers is a new hyperfine interaction method which dramatically extends the range of nuclear species which can be
polarized, as well as the fluxes and densities which can be achieved and the temperature range in which experiments can be
carried out. Lasers are ideally suided for the production of polarized atomic beams, as will be illustrated for the cases
of6,7Li,23Na and3He. Techniques for polarizing dense atomic vapors will be described with an emphasis on achieving full Doppler coverage by
the method of velocity changing collisions. Experiments leading to the production of a6Li target for a parity non-conservation study of the nuclear reaction6Li(α,γ)10B will be reviewed and results obtained to date presented. 相似文献