Search results for "MSS"
showing 10 items of 2513 documents
O(alpha_s) Spin-Spin Correlations for Top and Bottom Quark Production in e+ e- Annihilation
1997
We present the full O(alpha_s) longitudinal spin-spin correlations for heavy-quark pair production at e+ e- high-energy colliders in closed analytical form. In such reactions, quark and antiquark have strongly correlated spins, and the longitudinal components are dominant. For the explicit computation of the QCD bremsstrahlung contributions, new phase-space integrals are derived. Explicit numerical estimates are given for t t_bar and b b_bar production. Around the Z-peak, QCD one-loop corrections depolarize the spin-spin asymmetry for bottom quark pairs by approximately -4%. For top pair production, we find at 350GeV a 0.6% increased polarization over a value of 0.4 in the longitudinal corr…
Evaluation using m.c.n.p. code of the bremsstrahlung energy spectrum produced by interactions between structural materials and accelerated electrons
2004
Abstract In order to design the biological shield of industrial accelerator plants, it is needed to have a good knowledge of the bremsstrahlung energy spectrum and the intensity of the bremsstrahlung produced by electron interactions with both products (usually water equivalent) and structural materials such as concrete, iron, aluminium. Using the MCNP code, a normalized bremsstrahlung energy spectrum was obtained for materials with average atomic number lower than or equal to 13 and irradiated with 5 and 10 Mev electrons, respectively; multiplying the spectrum by suitable coefficients, it was possible to obtain the real spectrum for materials such as water, concrete, aluminium and iron. Th…
SU-FF-T-180: Dosimetric Characteristics of Tm-170 as a Radionuclide for Its Possible Use in Brachytherapy
2006
In clinical brachytherapy several types of photon sources are used, mainly Cs‐137, Ir‐192, I‐125, and Pd‐103. The Tm‐170 is a promising radionuclide for use in brachytherapy because of the low mean‐energy (46.75 keV or 66.39 keV if the lines below 10 keV are removed) and the possible high specific activity (2.21×1014 Bq/g for a half life of 128.6 days). Tm‐170 is produced in a nuclear reactor by neutron absorption of the natural Tm‐169 and decays mainly via β‐emission. The maximum energies of the β‐rays are 0.290 and 0.323 MeV. These β particles are thus absorbed in the source core and in the encapsulation cover producing bremsstrahlung that contributes significantly to the dose. These fact…
The Two‐Component X‐Ray Broadband Spectrum of X Persei Observed byBeppoSAX
1998
We report temporal and broadband (0.1-200 keV) spectral analysis of the Be/X-ray binary X Persei observed by the Narrow Field Instruments (NFI) on board the BeppoSAX satellite. The source luminosity is ~1.2 × 1034 ergs s-1 in the energy range 0.1-10 keV and ~2.4 × 1034 ergs s-1 in the range 0.1-200 keV. The source shows pulsations from 0.1 keV up to 80 keV. No variations of the pulse profile with energy are visible. The barycentric pulse period is 837.376 ± 0.026 s, in agreement with the secular spin-down observed since 1978. The 0.1-10 keV energy spectrum can be well fitted by a power law plus high-energy cutoff, in agreement with previous observations, although at higher energies a hard e…
Photon Asymmetry of Deuteron Photodisintegration Between 160 and 410 MeV
1999
The photon asymmetry Σ of the reaction has been measured across the photon energy range 160–410 MeV at the Mainz Microtron MAMI. Linearly polarized photons were obtained from coherent bremsstrahlung and their energies were determined with the Glasgow tagging spectrometer. The large acceptance detector DAPHNE enabled the outgoing protons to be measured over the complete azimuthal range and for polar angles from 35° to 155° in the c.m. system. The data are compared with existing results and recent theoretical calculations.
Über eine eichung eines 7.5 × 7.5 cm - NaJ(Tl) - Vollkristalls zur absolutzählung flächenförmiger präparate
1966
Abstract The photopeak efficiency and the peak-to-total ratio for a 7.5 × 7.5 cm solid NaI(Tl)-crystal are determined in the range of 0.145–1.33 MeV. The disintegration rates of the disc sources used are known by 4 πβ -and 4 πβ - γ -coincidence measurements. The effect of the disc diameter and the distance source-crystal on the photopeak efficiency is studied thoroughly. The data obtained are compared with those of other authors. The evaluation of the photopeak area is performed in a frequency diagram, a special type of probability scale, in which both parts of the Gaussian curve are represented by straight lines. Hence, corrections for the Compton overlap, bremsstrahlung and background can…
Enhancement of Bremsstrahlung Radiation Generated by Electron Beam Interaction in an Axially-Oriented Scintillator Crystal (Poster)
2019
Since their discovery, scintillator materials have played an important role in nuclear and particle physics, as well as in medical and industrial imaging. [...]
Electron heating, time evolution of bremsstrahlung and ion beam current in electron cyclotron resonance ion sources
2010
This thesis is a study of Electron Cyclotron Resonance Ion Source (ECRIS) plasmas and their properties. The focus has been on time evolution studies of bremsstrahlung emission, ion beam current production and numerical studies of electron heating in ECRIS plasmas. The time scales for reaching steady state bremsstrahlung production at electron energies greater than 30 keV is shown to be on the order of several hundreds of milliseconds. The ion beam currents of different elements are shown to reach steady state before the bremsstrahlung production. It is also demonstrated that by tuning the RF pulse patterns, the so-called preglow transient ion beam currents can be utilized while the amount o…
Vidējā pirmsskolas vecuma bērnu piederības izjūtas attīstība kolāžu veidošanas procesā
2018
Kvalifikācijas darba temats – Vidēja pirmsskolas vecuma bērnu piederības izjūtas attīstība kolāžu veidošanas procesā. Darba autore – Ieva Strapcāne-Abase Darba zinātniskais vadītājs – prof. Dr. paed. Maruta Sīle Pētījuma mērķis – Pētīt vidējā pirmsskolas vecuma bērnu ģimenes piederības izjūtas attīstību kolāžu veidošanas procesā. Pētījuma hipotēze – Vidējā pirmsskolas vecuma bērnu ģimenes piederības izjūtas attīstība kolāžu veidošanas procesā būs veiksmīgāka, ja: •tiks ievērota bērna iepriekšējā pieredze; •tiks ievērotas bērnu intereses; •tiks izvēlēti bērna vecumam atbilstoši praktiskie darbi. Teorētiskajā daļā tiek analizēta zinātniskā literatūra par piederības izjūtu un tās attīstību, ra…
Vecākā pirmsskolas vecuma bērnu radošuma pilnveide literāro pasaku klausīšanās procesa ietekmē
2018
Darba autors. Ina Vanaga Darba zinātniskais vadītājs. Dr. paed. Dagnija Vigule Bakalaura darba nosaukums. Vecākā pirmsskolas vecuma bērnu radošuma pilnveide literāro pasaku klausīšanās procesa ietekmē. Darba saturs. 83 lpp., 2 daļas, 8 attēli, 12 tabulas, 6 pielikumi, 51 literatūras un informācijas avoti. Pētījuma mērķis. Teorētiski un praktiski izpētīt vecākā pirmsskolas vecuma bērnu radošuma pilnveides iespējas pasaku klausīšanās ietekmē. Darba izvirzītā hipotēze. Vecākā pirmsskolas vecuma bērnu radošuma pilnveide būs sekmīga, ja tiks ņemta vērā vecākā pirmsskolas vecuma bērnu vispārīgās attīstības likumsakarības un izvēlētas speciāli atlasītas literārās pasakas. Darba pirmajā daļā apskat…