共查询到20条相似文献,搜索用时 12 毫秒
1.
V. M. Bystritsky V. V. Gerasimov J. Woźniak 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):79-84
The measurement method and results measuring of the stopping
power ratio of helium-3 and deuterium atoms for muons slowed down
in the D/3He mixture are presented. Measurements were performed
at four values of pure 3He gas target densities, ϕHe
= 0.0337, 0.0355, 0.0359, 0.0363 (normalized to the liquid
hydrogen density) and at a density 0.0585 of the D/3He mixture.
The experiment was carried out at PSI muon beam μE4 with the
momentum Pμ= 34.0 MeV/c. The measured value of the mean
stopping ratio S$_{3^He/D}$ is 1.66±0.04. 相似文献
2.
V. Bystritsky W. Czaplinski N. Popov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):185-191
The deexcitation of excited muonic protium and deuterium in the mixture of hydrogen and helium isotopes is considered. Methods
of experimental determination of the probability of direct atomic muon capture by hydrogen and muon transfer rates from excited
muonic hydrogen to helium are proposed. Theoretical results for the population of the muonic atoms in the ground state, , are compared with the existing experimental data. Results obtained for mixtures are of interest for investigation of nuclear fusion in muonic molecules.
Received: 6 August 1998 / Revised: 1st October 1998 / Accepted: 2 October 1998 相似文献
3.
A. Adamczak J. Gronowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):493-497
The diffusion radius of the 1S muonic hydrogen atoms in gaseous
H2 targets with various deuterium admixtures has been
determined for temperatures T=30 and 300 K. The Monte Carlo
calculations have been performed using the partial differential cross
sections for pμ and dμ atom scattering from the molecules
H2, HD and D2. These cross sections include
hyperfine transitions in the muonic atoms, the muon exchange between
the nuclei p and d, and rotational-vibrational transitions in the
target molecules. The Monte Carlo results have been used for preparing
the time-projection chamber for the high-precision measurement of the
nuclear μ- capture in the ground-state pμ atom, which is
now underway at the Paul Scherrer Institute. 相似文献
4.
A. Igarashi N. Toshima 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):425-430
The cross sections for p- + (Hμ-)1s (H = p, d, t)
are calculated in the hyperspherical close-coupling method
for collision energies below the (Hp-)n=4 threshold.
The results show good convergence with respect to basis size.
The formation cross section of (Hp-)n=2 is dominant and
two orders of magnitude larger than that of (Hp-)n=1 below
the (Hp-)n=3 threshold,
while the (Hp-)n=3 formation cross-section exceeds that for (Hp-)n=2 formation
above the (Hp-)n=3 threshold.
Resonance parameters are also calculated
below thresholds of (Hp-)n=2-4. 相似文献
5.
S. Tresch R. Jacot-Guillarmod F. Mulhauser L.A. Schaller L. Schellenberg H. Schneuwly Y.-A. Thalmann A. Werthmüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):93-97
The present status of research of muon transfer from the ground state of muonic protium to 4He is reviewed. The analysis of a recent measurement in a triple gas mixture of H2+4He+Ne at 15 bar and room temperature is presented and the result is compared to the existing experimental and theoretical
rates. The average muon transfer rate from protium to 4He determined from all lifetime measurements is .
Received: 22 January 1998 / Revised: 4 March 1998 / Accepted: 31 March 1998 相似文献
6.
R.A. Sultanov W. Sandhas V.B. Belyaev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):33-37
Muon-transfer rates in collisions of hydrogen-like atoms or with light nuclei t, 3He, 4He, 6Li or 7Li, are calculated in a semiclassical approximation to the Faddeev-Hahn equations. The two nuclei involved are treated classically,
while the motion of the muon in their Coulomb field is considered from the quantum mechanical point of view. The experimentally
observed strong dependence on the charge of the nuclei is reproduced.
Received: 1st November 1997 / Revised: 26 March 1998 / Accepted: 18 August 1998 相似文献
7.
The muon transfer rates from hydrogen isotopes (p,d) to 3,4He2+ and
6,7Li3+ ions are calculated in
the hyperspherical close coupling method.
Well converged results are obtained.
The present rates are comparable to those of existing calculations for He2+,
but they are much larger for Li3+.
The resonance parameters are also calculated for resonances near the (Hμ)1s threshold. 相似文献
8.
W. Czapliński A. Kravtsov A. Mikhailov N. Popov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(3):223-227
Nuclear fusion reactions in hydrogen-lithium muonic molecules, (where h=p,d,t) are considered and fusion rates from rotational states J=0 of the molecules are presented. Results obtained depend on the isotopic composition of the molecules and range between
and . The upper limit for fusion rates from rotational states J=0 of hydrogen-helium muonic molecules, and , equal , is also found.
Received: 4 December 1997 / Revised: 30 April 1998 / Accepted: 7 May 1998 相似文献
9.
D. Viel 《Il Nuovo Cimento D》1991,13(11):1361-1367
Summary The scattering of μp atoms in the 1S state from gold atoms was calculated using semi-classical methods. The results were used
to write a Monte Carlo program simulating backscattering from a gold surface. For isotropically incident μp of kinetic energy
(0.035–10) eV it was found that approximately 5% escape from the surface. The fraction backscattered showed little dependence
on the initial μp kinetic energy but increased greatly with incident angle from the normal to the surface. 相似文献
10.
A. Ghoshal P. Mandal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):251-258
An exponential correlated basis set is tested within the framework
of multi-channel Schwinger variational principle in the momentum space.
It is found that inclusion of only the
positron-electron correlation in the basis set is
enough to obtain accurate results for all significant partial
waves for ground state positronium
formation in positron-hydrogen collisions at low and intermediate energies (6.856–75 eV).
Results are in conformity with other accurate
variational and non-variational calculations as well as observed data available in the
literature. 相似文献
11.
Y. Susuki 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):31-38
Neutral fractions of specularly reflected beams have been measured for the glancing-angle incidence of (0.2-0.5) MeV ions on a clean (001) surface of SnTe. The measured fractions have been compared with the results calculated by a classical
model for charge exchanges and by a model based on the first-order perturbation theory. The experimental and calculated results
have differed greatly. The disagreements are attributed to collisions with valence electrons on the surface. The electron
capture cross-sections of (0.2-0.5) MeV ions for valence electrons have been derived, based on the measured neutral fraction and distribution of valence electrons
for jellium background positive charges, and are found to be about ten times larger than those for the outermost electrons
of Sn and Te atoms calculated by the classical model.
Received: 23 October 1998 相似文献
12.
R. Schmidt H. Daniel F.J. Hartmann P. Hauser F. Kottmann M. Mühlbauer C. Petitjean W. Schott D. Taqqu P. Wojciechowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):119-122
The stopping power of gaseous hydrogen for positive and negative muons at energies ranging from 3 to 100 keV has been measured
by time-of-flight. A pronounced Barkas effect was observed: the energy loss in hydrogen for negative muons was found to be
significantly smaller than that for positive muons.
Received: 23 April 1998 / Accepted: 7 May 1998 相似文献
13.
S. Karshenboim U. Jentschura V. Ivanov G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):209-215
We present an analytical evaluation of radiative corrections in exotic atoms induced by the one-loop electronic vacuum polarization.
We evaluate corrections to the energy levels, to the wave function (at the origin) and to the hyperfine structure. We treat
all corrections analytically within a non-relativistic approximation. Agreement is found with a few available numerical results.
The analytical treatment allows to determine the asymptotic forms of the corrections in the limit of a small atomic radius,
which for the atomic systems considered corresponds to a large mass of the constituent particle as compared to the electron
mass. The asymptotics can be verified using the effective charge approach.
Received: 28 January 1998 / Accepted: 13 March 1998 相似文献
14.
V. Bystritsky W. Czapliński M. Filipowicz E. Guła N. Popov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):75-83
The time-dependence of the population of muonic hydrogen states in hydrogen-helium mixtures is calculated for principal quantum
number n. The number of muons transferred to helium nuclei is also determined. The dependence of the population of the ground state
of muonic hydrogen on time and target density and the helium concentration is also considered. The results are in agreement with recent experimental
data. The comparison of the calculated yield of K lines of X-ray in pure hydrogen and deuterium with experimental data indicates the essential role of the Coulomb deexcitation
process. Possible Stark mixing is also analysed.
Received 17 February 1999 and Received in final form 9 June 1999 相似文献
15.
B. Nath C. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(3):295-302
The positronium formation cross-sections in the ground and excited n=2 levels have been studied in an -He atom collision in the framework of eikonal approximation. Both the differential and total formation cross-sections have
been investigated in the intermediate- and high-energy regime. Present eikonal results are found to differ appreciably from
the corresponding first Born values even at very high incident energies. The total cross-section results have been compared
with available experiments due to different groups as well as with other existing theoretical results.
Received: 20 July 1998 / Received in final form: 5 January 1999 相似文献
16.
P. Strasser T. Matsuzaki K. Nagamine 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):197-202
X-ray spectroscopy of muonic atoms is an important tool to obtain information on the nuclear charge distribution of nuclei.
It has been successfully used for many years to study stable isotopes in condensed or gaseous states. A new method has been
proposed to extend muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable
nuclei. This new method allows studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic
X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility
study at RIKEN-RAL muon facility is also reported.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
17.
P. Sigmund 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):45-54
The principle of reciprocity, i.e., the invariance of the
inelastic excitation in ion-atom collisions against interchange of
projectile and target, has been applied to the electronic stopping cross
section of low-velocity ions and tested empirically on
ion-target combinations supported by a more or less adequate amount of
experimental data. Reciprocity is well obeyed (within ~10%) for
many systems studied, and deviations exceeding ~20% are
exceptional. Systematic deviations such as gas-solid or metal-insulator
differences have been looked for but not identified on the present basis.
A direct consequence of reciprocity is the equivalence of Z1 with
Z2 structure for random slowing down. This feature is reasonably well
supported empirically
for ion-target combinations involving carbon, nitrogen, aluminium and
argon.
Reciprocity may be utilized as a criterion to reject questionable
experimental data. In cases where a certain
stopping cross section has not been or cannot be measured, the
stopping cross section for the inverted system may be available and
serve as a first estimate.
It is suggested to build in reciprocity as a fundamental requirement into
empirical interpolation schemes directed at the stopping of low-velocity
ions. Examination of the SRIM and MSTAR codes reveals cases where
reciprocity is obeyed accurately, but deviations of up to a factor of two
are common. In case of heavy ions such as gold, electronic stopping
cross sections predicted by SRIM are asserted to be almost an order of
magnitude too high. 相似文献
18.
K. Maniadaki L.A.A. Nikolopoulos P. Lambropoulos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):205-209
We present detailed calculations for one- and two-photon above-threshold detachment (ATD) cross-sections of the negative positronium
ion Ps
-
(
e
+
e
-
e
-
), below the threshold of Ps(n
= 2), using a configuration interaction (CI) method on a B splines basis. Both the one- and two-photon detachment cross-sections
have a form similar to the corresponding spectra of the H- ion, scaled accordingly. The peak value of the one-photon cross-section agrees very well with the calculations by Bathia
and Drachman [1], while it differs from those by Igarashi et al. [2], which give a value of 15% lower. Two-photon detachment cross-sections are also reported.
Received 24 January 2002 / Received in final form 9 April 2002 Published online 19 July 2002 相似文献
19.
L.B. Madsen L.A.A. Nikolopoulos P. Lambropoulos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(1):67-79
Ab initio time-dependent (TD) calculations of the behavior of positronium (Ps) under strong subpicosecond laser pulses are presented.
The results are compared with results in H through scaling. It is found that a substantial amount of the population can be
found in excited states after the pulse. In the perturbative regime, generalized multiphoton ionization cross-sections are
extracted from the results of the time-dependent calculations. The generalized cross-sections are used to predict the response
of Ps to nanosecond laser pulses at wavelengths of current experimental interest. Beyond the application to Ps, the generality
of the method for extracting generalized cross-sections from TD nonperturbative calculations is discussed.
Received 8 June 1999 相似文献
20.
L. González-Sánchez E. Bodo F. A. Gianturco 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):65-72
An ab initio computed potential energy surface is employed to
evaluate the interaction of the OH+(3Σ -) molecule with
4He(1S) atom and an analytic fitting of the raw points is
directly employed in quantum scattering calculations at ultralow
collision energies. The Hund's case (b) chosen to handle the
spin-rotation coupling allows to extract from the numerous inelastic
cross sections the relative importance of pure “spin flip" vis-à-
vis rotational cooling cross sections. The final rates of all the
above processes as a function of the initial |N〉 state are
analysed in detail and possible propensity rules are discussed. 相似文献