28 research outputs found
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
[Study of H-2 mutations in mice. VII. The defectiveness of the H-2ba mutant in the hemagglutination and graft vs host reactions]
Three mutants of the H-2K gene within the mouse major histocompatibility complex were studied. Antisera anti-H-2.5 + 39 were unable to agglutinate H-2ba and H-2bf mutant red blood cells. The same sera moderately agglutinated H-2b red blood cells. The H-2ba red blood cells did not absorb in vitro the activity from an anti-H-2.5 serum, while the H-2b cells did. Thus, these results indicate the existence of qualitative SD antigenic differences among H-2Kb derived mutants. In the proliferative graft versus host test the H-2ba spleen cells did not induce spleen enlargement in the H-2bd recipients, while pronounced reaction was recovered in bd-ba combination. The (baXb) F1 hybrid cells were as efficient as b/b homozygous cells. The data suggest that the H-2K gene product may be involved in the antigen recognition process by T cells
Adaptation to Abundant Low Quality Food Improves the Ability to Compete for Limited Rich Food in Drosophila melanogaster.
The rate of food consumption is a major factor affecting success in scramble competition for a limited amount of easy-to-find food. Accordingly, several studies report positive genetic correlations between larval competitive ability and feeding rate in Drosophila; both become enhanced in populations evolving under larval crowding. Here, we report the experimental evolution of enhanced competitive ability in populations of D. melanogaster previously maintained for 84 generations at low density on an extremely poor larval food. In contrast to previous studies, greater competitive ability was not associated with the evolution of higher feeding rate; if anything, the correlation between the two traits across lines tended to be negative. Thus, enhanced competitive ability may be favored by nutritional stress even when competition is not intense, and competitive ability may be decoupled from the rate of food consumption
Evaluation of Fermi read-out of the Atlas Tilecal prototype
Prototypes of the FERMI system have been used to read out a prototype of the ATLAS hadron calorimeter in a beam test at the CERN SPS. The FERMI read-out system, using a compressor and a sampling ADC, is compared to a standard charge integrating read-out by measuring the energy resolution of the calorimeter separately with the two systems on the same events.http://www.sciencedirect.com/science/article/B6TJM-3SYVH5K-41/1/c7deb04cd1c94e28ecafdeda8aea0d1
A measurement of the energy loss spectrum of 150 GeV muons in iron
The energy loss spectrum of 150 GeV muons has been measured with a prototype of the ATLAS hadron calorimeter in the H8 beam of the CERN SPS. The differential probability dP/d upsilon per radiation length of a fractional energy loss upsilon = Delta E(mu)E(upsilon) has been measured in the range upsilon = 0.01 divided by 0.95; it is compared with the theoretical predictions for energy losses due to bremsstrahlung and production of electron-positron pairs or of energetic knock-on electrons. The integrated probability integral(0.01)(0.95)(dP/d upsilon)d upsilon is (1.610 +/- 0.015(stat) +/- 0.105(syst)). 10(-3) in agreement with the theoretical predictions 1.556 . 10(-3) and 1.619 . 10(-3). Agreement with theory is also found in two intervals of upsilon where production of electron-positron pairs and knock-on electrons dominates. In the region of bremsstrahlung dominance (upsilon = 0.12 divided by 0.95) the measured integrated probability (1.160 +/- 0.040(stat) +/- 0.075(syst)). 10(-4) is in agreement with the theoretical value of 1.185 . 10(-4), obtained using the Petrukhin and Shestakov description of the bremsstrahlung process. The same result is about 3.6 standard deviations (defined as the quadratic sum of statistical and systematic errors) lower than the theoretical prediction of 1.472 . 10(-4) obtained using Tsai's description of bremsstrahlung
Response of the ATLAS Tile calorimeter prototype to muons
A study of high energy muons traversing the ATLAS hadron the calorimeter in the barrel region in the energy range between 10 and 300 GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (10(34) l/cm(2) s). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be 0.81 +/- 0.03; the e/mu ratio is in the range 0.91-0.97. The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution