排序方式: 共有46条查询结果,搜索用时 31 毫秒
11.
Prakhov S Tippens WB Allgower C Bekrenev V Berger E Briscoe WJ Clajus M Comfort JR Craig K Grosnick D Huber GM Isenhower D Knecht N Koetke D Koulbardis A Kozlenko N Kruglov S Kycia T Lolos GJ Lopatin I Manley DM Marusic A Manweiler R McDonald S Nefkens BM Olmsted J 《Physical review letters》2000,84(21):4802-4805
We report the first determination of the upper limit for the branching ratio of the CP forbidden decay eta-->4pi(0). No events were observed in a sample of 3.0x10(7) eta decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated pi(-) beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B(eta-->4pi(0))=6. 9x10(-7). 相似文献
12.
G. Medeiros-Ribeiro A. Malachias S. Kycia R. Magalhães-Paniago T.I. Kamins R. Stanley Williams 《Applied Physics A: Materials Science & Processing》2005,80(6):1211-1214
Self-assembled nanocrystals grown by epitaxy represent a viable way to mass produce quantum structures exhibiting novel electronic properties. In order to infer the electronic properties of such systems, knowledge of both composition and strain is necessary. Here, detailed maps of these quantities were obtained by anomalous X-ray diffraction for samples grown at 600 °C and 700 °C by chemical vapor deposition and molecular beam epitaxy, respectively – two different temperatures and growth techniques. From these maps, the elastic energies stored in the islands were evaluated. It was found that the elastic energy is concentrated at the island borders, regardless of the growth temperature or method. In contrast, the regions with the lowest elastic energy were the island core and top. These results provide insight into the mechanisms that govern the growth and evolution of strained nanocrystals. PACS 71.35.Ji; 78.67.Hc; 73.22.Dj 相似文献
13.
A.S. Carroll T.F. Kycia K.K. Li D.N. Michael P.M. Mockett D.C. Rahm R. Rubinstein 《Physics letters. [Part B]》1973,45(5):531-534
Measurements have been carried out of total cross sections of positive kaons on hydrogen and deuterium to a statistical precision of better than ± 0.1 mb for most points in the range of laboratory momentum from 410 to 1065 MeV/c in intervals of approximately 50 MeV/c. A very broad elastic structure in the I = 0 state is inferred. 相似文献
14.
R.J. Abrams A.S. Carroll T.F. Kycia K.K. Li D.N. Michael P.M. Mockett R. Rubinstein 《Physics letters. [Part B]》1973,45(1):66-68
We have searched for the decay πO → 4γ using the decay K± → π±πO as a source of kinematically defined πO,s. No events were observed, where one event would correspond to a branching ratio (πO → 4γ)/(πO → 2γ) of 2.7 × 10?5. 相似文献
15.
ac susceptibility measurements are presented on the dilute, dipolar coupled, Ising magnet LiHoxY1-xF4 for a concentration x=0.045. The frequency and temperature dependences of the susceptibility show characteristic glassy relaxation. The absorption spectrum is found to broaden with decreasing temperature suggesting that the material is behaving as a spin glass and not as an exotic spin liquid as was previously observed. A dynamical scaling analysis suggests a spin glass transition temperature of 43+/-2 mK with an exponent znu=7.8+/-0.2. 相似文献
16.
J.C. de Lima A.R. Jerônimo A. Gomez S.M. Souza D.M. Trichês C.E.M. Campos T.A. Grandi S. Kycia 《Journal of Non》2008,354(40-41):4598-4602
The atomic structure of an amorphous Si24Nb76 alloy produced by mechanical alloying was investigated by using one X-ray total structure factor S(K) as input data for reverse Monte Carlo (RMC) simulations. The partial SSi–Si(K), SSi–Nb(K), SNb–Nb(K) structure factors and GSi–Si(r), GSi–Nb(r), GNb–Nb(r) pair probability functions were obtained from the RMC simulations. The structural parameters (interatomic distances and co-ordination numbers) for the first neighbors were extracted and compared with those found in the Nb3Si compound. It was observed some resemblance between these phases. 相似文献
17.
Stephan Sch ttl Erwin A. Schuberth Jan B. Kycia William P. Halperin 《Physica B: Condensed Matter》2000,280(1-4):174-175
In order to distinguish the UPt3 superconducting (s.c.) phases we have studied their magnetic properties at low fields in a SQUID magnetometer and up to fields >Hc2(0) with a capacitive torque-meter. With the SQUID we measure the magnetic penetration depth and find the second s.c. transition at Tc− when the field is applied along the c-axis, but not with
. This result, combined with power-law behavior at low temperature T, is most consistent with the two-dimensional E2u s.c. order parameter. Below 20 mK we find an additional diamagnetic signal that we ascribe to the normal state magnetism. In high fields our torque measurements show a kink of the perpendicular magnetization component at the B–C phase line, pointing to an enhanced Ginzburg–Landau parameter in the C phase. 相似文献
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Atiya MS Chiang IH Frank JS Haggerty JS Ito MM Kycia TF Li KK Littenberg LS Stevens A Strand RC Louis WC Akerib DS Hildreth M Marlow DR Meyers PD Selen MA Shoemaker FC Smith AJ Azuelos G Blackmore EW Bryman DA Felawka L Kitching P Kuno Y Macdonald JA Numao T Padley P Poutissou JM Poutissou R Roy J 《Physical review letters》1989,63(20):2177-2180
20.
W. P. Halperin D. T. Sprague T. M. Haard J. B. Kycia Y. Lee M. R. Rand 《Czechoslovak Journal of Physics》1996,46(6):2989-2994
The transition to superfluidity of3He in high porosity (98.2%) acrogel has been observed by nuclear magnetic resonance techniques. The onset of the transition at all pressures above 13 bar is marked by a sharp increase in NMR frequency similar to that observed in bulk3He-A. This suggests that the aerogel/superfluid phase is highly homogeneous although both the transition temperature, Tc, and the amplitude of the order parameter are substantially suppressed. The acrogel strands are ≈ 50Å in diameter, much smaller than the superfluid coherence length. Consequently, we have attempted to interpret our observations as an impurity scattering problem. Based on our measurements of the magnetic field dependence of Tc it appears that both magnetic and potential scattering play important roles where the magnetic scattering can be associated with solid3He on the aerogel surface. This is determined by isotopic exchange with4He, a process which appears to stabilize a new superfluid state similar to the bulk B-phase. 相似文献