97 research outputs found
Measurement of the cross section with the CMD-3 detector at the VEPP-2000 collider
The process has been studied in the
center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23
pb collected with the CMD-3 detector at the VEPP-2000 collider.
Using about 24000 selected events, the cross
section has been measured with a systematic uncertainty decreasing from 11.7\%
at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of
production dynamics has been performed
Study of the process in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector
Using a data sample of 6.8 pb collected with the CMD-3 detector at the
VEPP-2000 collider we select about 2700 events of the process and measure its cross section at 12 energy ponts with about
6\% systematic uncertainty. From the angular distribution of produced nucleons
we obtain the ratio
Study of irradiation temperature effect on change of structural, optical, and strength properties of BeO ceramics when irradiated with Ar8+ and Xe22 heavy ions
This paper presents the results of the study of the effect of irradiation temperature on structural and optical distortions and deformations, as well as the strength properties of BeO ceramics as a result of irradiation with Ar8+ and Xe22+ ions at a radiation dose of 5 × 1013 cm-2. The choice of radiation dose is due to the effect of overlapping defective areas arising along the trajectories of ions in ceramics, which makes it possible to model radiation damage caused by the effect of accumulation as a result of cascade collisions and overlapping damaged areas. The temperature range of 300–1000 K was chosen to simulate different operating conditions, as well as the possibility of simulating partial annealing of defects during irradiation at high temperatures. During the research, it was established that high-temperature radiation reduces influence of size of electronic and nuclear power losses of ions of Ar8+ and Xe22+ with energy of 70 MeV and 231 MeV, respectively, on extent of radiation damage of ceramics of BeO. Irradiation at a temperature of 1000 K results in an equal 14% change in dislocation density for these particles, a comparable decrease in the yield intensity of optically stimulated luminescence by 5% and 15%, as well as microhardness by 25% and 30%, respectively. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08855828)
Measurement of the Pion Form Factor in the Energy Range 1.04-1.38 GeV with the CMD-2 Detector
The cross section for the process is measured in the
c.m. energy range 1.04-1.38 GeV from 995 000 selected collinear events
including 860000 events, 82000 events, and 33000
events. The systematic and statistical errors of measuring the
pion form factor are equal to 1.2-4.2 and 5-13%, respectively.Comment: 5 pages, 2 figure
News from the Muon (g-2) Experiment at BNL
The magnetic moment anomaly a_mu = (g_mu - 2) / 2 of the positive muon has
been measured at the Brookhaven Alternating Gradient Synchrotron with an
uncertainty of 0.7 ppm. The new result, based on data taken in 2000, agrees
well with previous measurements. Standard Model evaluations currently differ
from the experimental result by 1.6 to 3.0 standard deviations.Comment: Talk presented at RADCOR - Loops and Legs 2002, Kloster Banz,
Germany, September 8-13 2002, to be published in Nuclear Physics B (Proc.
Suppl.); 5 pages, 3 figure
Search for Lorentz and CPT Violation Effects in Muon Spin Precession
The spin precession frequency of muons stored in the storage ring has
been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT
violation signatures were searched for: a nonzero
(=); and a sidereal variation of
. No significant effect is found, and the following
limits on the standard-model extension parameters are obtained: GeV; GeV; and the 95% confidence level limits
GeV and
GeV.Comment: 5 pages, 3 figures, submitted to Physical Review Letters, Modified to
answer the referees suggestion
The Muon Anomalous Magnetic Moment and the Standard Model
The muon anomalous magnetic moment measurement, when compared with theory,
can be used to test many extensions to the standard model. The most recent
measurement made by the Brookhaven E821 Collaboration reduces the uncertainty
on the world average of a_mu to 0.7 ppm, comparable in precision to theory.
This paper describes the experiment and the current theoretical efforts to
establish a correct standard model reference value for the muon anomaly.Comment: Plenary Talk; PANIC'02 XVI Particles and Nuclear International
Conference, Osaka, Japan; Sept. 30 - Oct. 4, 2002; Report describes the
published 0.7 ppm result and updates the theory statu
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