共查询到20条相似文献,搜索用时 312 毫秒
1.
T. Matsuzaki K. Nagamine K. Ishida S.N. Nakamura N. Kawamura M. Tanase M. Kato K. Kurosawa M. Hashimoto H. Sugai K. Kudo N. Takeda G.H. Eaton 《Hyperfine Interactions》1999,118(1-4):229-234
X-ray and neutron measurements were carried out for muon catalyzed fusion and related phenomena in solid T2. The X-ray originated from the μ- to α sticking in muon catalyzed fusion; t + t + μ
-
→ (μ
-
α) + 2n was measured for the first time, yielding K
α
X-ray intensity of (μα) atom and the intensity ratio of K
β
to K
α
. Utilizing the phenomena of 3He accumulation in solid T2, the X-ray in the μ- transfer process from (tμ) to 3He was detected, providing a formation rate and radiative decay branching-ratio of (t
3Heμ) molecule. From fusion neutron measurements, estimated values were obtained for (ttμ) molecular formation rate as well as sticking probability ωt in ttμ fusion. A possible new insight in t + t fusion reaction process at a low energy limit is also obtained.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Karen B. Paul 《Central European Journal of Physics》2005,3(1):115-126
A monocrystal ofFe
3
O
4 is characterized by resistance, magnetoresistance and magnetic measurements in a temperature range from 4.2 K to 350 K and
magnetic field-cycling from −9 T to 9 T. The resistance measurements revealed a metal-insulator Verwey transition (VT) atT
v
=123.76 K with activation energy E=92.5 meV at T >T
v
and temperature-substitute for the activation energy below the VT,T
0=E/k
B
≈3800 K within 70 K–110K. The magnetotransport results independently verified the VT at 123.70 K, with discontinuous change
in the magnetic moment ΔM≈0.21 ΔM≈0.21μ
B
and resistance hysteresis, dependent on the magnetic field in a narrow temperature range of 0.4° around theT
v
. The magnetic characterization established self consistentlyT
v
as ≈123.67 K, the jump in the magnetization at the VT≈0.25μ
B
and confirmed, that the magnetocrystalline anisotropy is the main microscopic mechanism responsible for the magnetization
of the monocrystal (88%) with additional natural and imposed defects contributing as 12%. 相似文献
3.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):229-241
We utilize existing inclusive data on K+-meson momentum spectra of the reaction pp→K
+
X at T
p = 2.3-2.85GeV to deduce total cross-sections for pp→K
+
Σ
+
n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T
p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained
for T
p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration
at a somewhat lower beam energy, indicating that the pp→K
+
Σ
+
n reaction cross-section could exhibit a rather unusual energy dependence. 相似文献
4.
B. Cameron Reed 《Central European Journal of Physics》2005,3(1):1-7
The ground-state energy of neutral helium is estimated variationally with a trial wavefunction of the form ϕ≈e
−γ(rA/a
o)ne−γ(rB/a
o)n. This model represents a modification of traditional textbook examinations of this problem via inclusion of the power “n”
as a second nonlinear variational parameter in addition to the usual effective nuclear charge γ and leads to an upper-limit
on the ground state energy of −2.86107 E
h
(E
h
=1 hartree) in comparison with the traditional (n=1) result of −2.84766 E
h
. This result represents a reduction of the percentage overestimate from the true ground-state energy (−2.90373 E
h
) of from 1.93 to 1.47. In comparison with the maximum accuracy obtainable from an uncorrelated trial wavefunction, −2.86168
E
h
, the present trial wavefunction reduces the percentage overestimate from 0.49 (n=1) to 0.021. The optimum values of (n, γ)
are determined to be ≈(0.897, 1.825). 相似文献
5.
A. Korgul H. Mach B. A. Brown A. Covello A. Gargano B. Fogelberg W. Kurcewicz E. Werner-Malento R. Orlandi M. Sawicka 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):25-29
Recently the first excited state in 135Sb has been observed at the unexpectedly low excitation energy of only 282keV and interpreted as mainly d
5/2 proton coupled to the 134Sn core. Based on theoretical considerations it was suggested that its low excitation energy is related to a relative shift
of the proton d
5/2 and g
7/2 orbits induced by the neutron excess. We have measured the lifetime of the 282keV state by the advanced time-delayed βγγ(t) method. The measured half-life, T
1/2 = 6.1(4)ns, yields exceptionally low limits of B(M1;5/21
+→7/21
+)≤3.0×10-4
μ
2
N and B(E2;5/21
+→7/21
+)≤54e
2
fm
4. These strongly hindered M1 and slow E2 transition rates are similar to those for the transition de-populating the first excited state at 405keV in 211Bi. Results of shell model calculations with realistic interactions are presented. The M1 decay rate was found to be extremely sensistive both to the wave function and to the M1 effective operator. 相似文献
6.
Influence of ion-molecular reactions on μ-capture in hydrogen and on fusion in 3Hedμ muonic molecule
The de-excitation processes (J=1)→ (J=0) in muonic molecular ions (ppμ)+ and (3Hedμ)+ are studied. It is shown that the rate of such transitions substantially depends on the chain of ion-molecular reactions
initiated by positively charged muonic ions.
The probabilities of ortho-para transition in the [(ppμ)+H2] and [(ppμ)+e] complexes formed as a result of chemical reactions in the pure hydrogen were estimated.
Taking into account the ion-molecular processes in D2 + He mixtures, the evaluation of the observed rate λf of nuclear fusion in the 3Hedμ muonic molecules was performed. The expected yield of fusion reactions per muon at the mixture density φ=0.1 and concentration
C
He
=0.05 was obtained to be equal to
.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
Katsumi Sugita Yoshiwo Okamoto Matsuo Sekine 《International Journal of Theoretical Physics》1997,36(6):1309-1316
We consider a simple Lagrangian which is constructed by only the preon and antipreon fields. By introducing the auxiliary
fields φμ, φ
μ
†
, and ϕμ, it is shown that φμ, φ
μ
†
, and ϕμ correspond to the electroweak gauge bosonsW
μ
+
,W
μ
−
, andW
μ
3
, respectively, which are composite particles of preons and antipreons. 相似文献
8.
P. Mohr 《The European Physical Journal A - Hadrons and Nuclei》2007,34(1):23-28
α-decay half-lives for 104, 105, 106Te and 108, 109, 110Xe close above the doubly-magic 100Sn are calculated from systematic double-folding potentials. The derived α preformation factors are compared to results for
212, 213, 214Po and 216, 217, 218Rn above the doubly-magic 208Pb. α-decay energies of Q
α = 5.42±0.07MeV and 4.65±0.15MeV are predicted for 104Te and 108Xe; the corresponding half-lives are T
1/2 ≈ 5ns for 104Te and of the order of 60μs for 108Xe. Additionally, the properties of rotational bands in 104Te are analyzed, and the first excited 2+ state in 104Te is predicted at E
x = 650±40keV; it decays preferentially by γ emission with a reduced transition strength of 10 Weisskopf units to the ground
state of 104Te and with a minor branch by α emission to the ground state of 100Sn. 相似文献
9.
The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd3+ ions in CaNb2O6 crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10−20 cm2 with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd3+ ions in CaNb2O6 crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω
t
are Ω
2=5.321×10−20 cm2,Ω
4=1.734×10−20 cm2,Ω
6=2.889×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β
1=36.03%,β
2=52.29%,β
3=11.15%,β
4=0.533%. The emission cross section at 1062 nm is 9.87×10−20 cm2. 相似文献
10.
Experimental Coulomb isotope shifts δE
Coul from K
α transitions, and radius differences δ〈r
2〉
eμ measured by electron scattering and muonic atom X-rays were used to derive ‘experimental’ coefficients C
1,exp for 54 isotope pairs of 18 elements from Mo to U. A χ2-analysis shows that these experimental coefficients are – on average – 3.5% lower than the theoretical C
1 values calculated by Seltzer, or more precisely: C
1,exp=0.965(± 0.014)×C
1. The need for more accurate theoretical calculations is stressed, and consequences of this deviation are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Manganese-doped ZnSiAs<Subscript>2</Subscript> chalcopyrite: A new advanced material for spintronics
L.?I.?Koroleva D.?M.?Zashchirinski? T.?M.?Khapaeva S.?F.?Marenkin I.?V.?Fedorchenko R.?Szymczak B.?Krzumanska V.?Dobrovol’ski? L.?Kilanski? 《Physics of the Solid State》2009,51(2):303-308
A new spintronics material with the Curie temperature above room temperature, the ZnSiAs2 chalcopyrite doped with 1 and 2 wt % Mn, is synthesized. The magnetization, electrical resistivity, magnetoresistance, and
the Hall effect of these compositions are studied. The temperature dependence of the electrical resistivity follows a semiconducting
pattern with an activation energy of 0.12–0.38 eV (in the temperature range 124 K ≤ T ≤ 263 K for both compositions). The hole mobility and concentration are 1.33, 2.13 cm2/V s and 2.2 × 1016, 8 × 1016 cm−3 at T = 293 K for the 1 and 2 wt % Mn compositions, respectively. The magnetoresistance of both compositions, including the region
of the Curie point, does not exceed 0.4%. The temperature dependence of the magnetization M(T) of both compositions exhibits a complicated character; indeed, for T ≤ 15 K, it is characteristic of superparamagnets, while for T > 15 K, spontaneous magnetization appears which correspond to a decreased magnetic moment per formula unit as compared to
that which would be observed upon complete ferromagnetic ordering of Mn2+ spins or antiferromagnetic ordering of spins of the Mn2+ and Mn3+ ions. Thus, for T > 15 K, it is a frustrated ferro- or ferrimagnet. It is found that, unlike the conventional superparamagnets, the cluster
moment μ
c
in these compositions depends on the magnetic field: ∼12000–20000μB for H = 0.1 kOe, ∼52–55μB for H = 11 kOe, and ∼8.6–11.0μB at H = 50 kOe for the compositions with 1 and 2 wt % Mn, respectively. The specific features of the magnetic properties are explained
by the competition between the carrier-mediated exchange and superexchange interactions. 相似文献
12.
Edward A. Desloge 《International Journal of Theoretical Physics》1976,15(5):357-363
On the basis of elementary symmetry arguments it is shown that (1) if in classical mechanics there exists a quantity λ+Σiμiυi+1/2νυ
2 that is conserved, where λ,μ
i, andν are particle parameters, then theμ
i andν are all proportional to a single parameterμ and the quantityAμ+ΣiBiμυi+C(λ+ 1/2Dμυ
2), whereD ≡ν/μ, is conserved for all values ofA, B
i, andC; (2) if in relativistic mechanics there exists a quantity λ+Σiμiυi[1−(υ
2/c
2)]−1/2+νc[1−(υ
2/c
2)]−1/2 that is conserved, then theμ
i andν are all proportional to a single parameterμ and the quantityAλ+ΣiBiμνi[1−(υ
2/c
2)]−1/2+Cμc [1−(υ
2/c
2)]−1/2 is conserved for all values ofA, B
i, andC. 相似文献
13.
We report a ZGP OPO system capable of producing >6 W at a signal wavelength of 3.80 μm and an idler wavelength of 4.45 μm.
The pumping source is the Tm,Ho:GdVO4 laser operated at 2.049 μm with an M
2 of 1.07. The ZGP OPO generated a total combined output power of 6.1 W at signal wavelength and idler wavelength under pumping
power of 18.3 W, and an M
2 of 1.7 for OPO output was obtained. 相似文献
14.
W. J. Kossler X. H. Yu A. Greer H. E. Schone C. E. Stronach M. Davis R. S. Cary J. E. Crow W. F. Lankford J. Oostens 《Hyperfine Interactions》1991,63(1-4):81-86
Transverse and zero-field μSR measurements were made on YBa2(Cu1−xNix)3O7−y withx=0.1 and 0.2, and YBa2(Cu1−x
Zn
x
)3O7−y
withx=0.03, 0.06, 0.1, and 0.16, wherey≈0.1. Since doping may lead to magnetic ordering this was searched for with both zero and transverse field μSR, but no evidence
was found over the temperature range studied: 10–100 K. However, depolarization rates as functions of temperature were obtained,
and the low temperature values of these are σ=3.2 μs−1.1.6μs−1, and 1 μs−1 forx=0.01, and 0.2 Ni, respectively, and σ=0.8 μs−1, 0.75 μs−1, 0.65 μs−1, and 0.4 μs−1 forx=0.03, 0.06, 0.1, and 0.16 Zn, respectively. Estimates for the effect of decreasing electron concentration for Zn are made,
but these alone do not account for the drop in σ. Estimates for the effect of scattering on λ and hence σ are made. The reduction
in σ for Ni dopant is in surprisingly good agreement with these estimates. For Zn the order of magnitude is correct, but the
relative lack of further change in σ after the effect of the first 0.03 addition seems to imply a saturation of the effect
of scattering. 相似文献
15.
Z. Zhu J. Li A. Brenier G. Jia Z. You X. Lu B. Wu C. Tu 《Applied physics. B, Lasers and optics》2007,86(1):71-75
Yb3+:GdAl3(BO3)4 (hereafter Yb3+:GAB) crystals with large sizes and good optical quality have been grown by the top-seed solution growth (TSSG) method. The polarized absorption and emission spectra have been investigated at room temperature. For the σ-polarization, the intensities of both absorption and emission spectra are stronger than those for the π-polarization, the σ-absorption cross section of Yb3+ in GAB being 3.43×10-20 cm2 at 977 nm, and the σ-emission cross section being 0.98×10-20 cm2 at 1045 nm. The fluorescence lifetime of the 2
F
5/2→2
F
7/2 transition was measured to be 800 μs in the 5% doped sample used for our laser experiments, 993 μs in a 10% doped sample and 569 μs in a 0.5% doped sample. The laser parameters were estimated as: βmin=0.022, Isat=10.4 kW/cm2 and Imin=0.23 kW/cm2. About 0.4 W laseroutput at the wavelength of 1043 nm was achieved when the Yb3+:GAB crystal was pumped by a 974 nm laser diode, with 27.4% slope efficiency. PACS 42.55.-f; 42.70.Hj; 78.20.-e; 81.10.Dn 相似文献
16.
E. N. Elekina A. A. Krutov A. P. Martynenko 《Physics of Particles and Nuclei Letters》2011,8(4):331-336
On the basis of quasi-potential approach to the bound state problem in QED we calculate the vacuum polarization, recoil and
structure corrections of orders α5 and α6 to the fine splitting interval ΔE
fs = E(2P
3/2) − E(2P
1/2) in muonic 24He ion. The resulting value ΔE
fs = 146180.68 μeV provides reliable guideline in performing a comparison with the relevant experimental data. 相似文献
17.
O. Silvestre M.C. Pujol M. Rico F. Güell M. Aguiló F. Díaz 《Applied physics. B, Lasers and optics》2007,87(4):707-716
This paper presents the crystal growth and optical characterization of thulium-doped KLu(WO4)2 (KLuW). Thulium-doped KLuW macrodefect-free monoclinic single crystals (a*×b×c≈10×7×15 mm3) were grown by the top seeded solution growth slow cooling method with dopant concentrations of 0.5%, 1%, 3% and 5% atomic
in solution. The evolution of unit cell parameters in relation with thulium doping was studied by X-ray powder patterns. Thulium
energy levels in the KLuW host were determined by 6 K polarized optical absorption. The Judd–Ofelt parameters determined were
Ω2=9.01×10-20 cm2, Ω4=1.36×10-20 cm2 and Ω6=1.43×10-20 cm2. The maximum emission cross section for the 1.9 μm emission, calculated by Füchtbauer–Ladenburg method, is 1.75×10-20 cm2, at 1845 nm with E//Nm. The intensity decay time from the emitting levels 1
G
4 and 3
H
4 levels in relation to the concentration were studied. For the lowest thulium concentration, the measured decay times from
1
G
4 and 3
H
4 emitting levels are 140 μs and 230 μs, respectively.
PACS 42.55.Rz; 78.20.-e; 78.55.-m 相似文献
18.
A. S. Rinat M. F. Taragin M. Viviani 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):415-416
We use the relation between Structure Functions (SFs) of nuclei A and nucleons N in order to fomulate a criterion which isolates the QE part out of the total inclusive cross-section. From data points around
the QEP we extract the reduced neutron magnetic form factor 〈α
n = G
M
n/μ
n
G
d〉. The latter shows an unexpected decrease up to Q
2 = 10GeV^2, the largest measured. 相似文献
19.
In this work we investigate the single- and the double-spin asymmetries at the collisions of polarized protons pp → (γ
*, Z
0, Z′) + X within the scope of QCD, the electroweak interaction and superstring E
6 theory. The helicity amplitude method is used. Analytical expressions for the single- and the double-spin asymmetries are
obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values
of invariant masses of the lepton pair. The pure contribution coming from the superstring Z′ boson on the single- and double- spin asymmetries has been extracted. The results obtained allow investigation of the spin
structure of the proton. 相似文献
20.
W. Schwarz E. H. Brandt K. -P. Döring U. Essmann K. Fürderer M. Gladisch D. Herlach G. Majer H. -J. Mundinger H. Orth A. Seeger M. Schmolz 《Hyperfine Interactions》1986,31(1-4):247-253
The diffusivityD
μ of positive muons (μ+) in the mixed state of superconducting high-purity, high-perfection niobium single crystals is investigated by measurements
of the relaxation of the transverse muon spin polarization (μ+SR). The method makes use of the strong magnetic field gradients existing in the mixed state of Type-II superconductors and
monitorsD
μ through the variation of the magnetic field felt by the μ+ during their diffusion through the crystals. For μ+ near the centres of the flux lines inNb it givesD
μ(4.6 K)=(8±2)·10−11m2S−1. The positive temperature coefficient ofD
μ indicates that at liquid-helium temperatures the diffusivity of μ+ inNb is mainly due to phonon-assisted tunnelling processes. 相似文献