| 1. |
- Wagner, L., et al.
(författare)
-
Astrophysical S factor of the N 14 (p,γ) O 15 reaction at 0.4-1.3 MeV
- 2018
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 97:1
-
Tidskriftsartikel (refereegranskat)abstract
- The N14(p,γ)O15 reaction is the slowest reaction of the carbon-nitrogen cycle of hydrogen burning and thus determines its rate. The precise knowledge of its rate is required to correctly model hydrogen burning in asymptotic giant branch stars. In addition, it is a necessary ingredient for a possible solution of the solar abundance problem by using the solar N13 and O15 neutrino fluxes as probes of the carbon and nitrogen abundances in the solar core. After the downward revision of its cross section due to a much lower contribution by one particular transition, capture to the ground state in O15, the evaluated total uncertainty is still 8%, in part due to an unsatisfactory knowledge of the excitation function over a wide energy range. The present work reports precise S factor data at twelve energies between 0.357 and 1.292 MeV for the strongest transition, capture to the 6.79-MeV excited state in O15, and at ten energies between 0.479 and 1.202 MeV for the second strongest transition, capture to the ground state in O15. An R-matrix fit is performed to estimate the impact of the new data on astrophysical energies. The recently suggested slight enhancement of the 6.79-MeV transition at low energy could not be confirmed. The present extrapolated zero-energy S factors are S6.79(0)=1.24±0.11 keV b and SGS(0)=0.19±0.05 keV b.
|
|
| 2. |
- Akhmadaliev, S., et al.
(författare)
-
Results from a new combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter
- 2000
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 449:3, s. 461-477
-
Tidskriftsartikel (refereegranskat)abstract
- A new combined test of an electromagnetic liquid argon accordion calorimeter and a hadronic scintillating-tile calorimeter was carried out at the CERN SPS. These devices are prototypes of the barrel calorimeter of the future ATLAS experiment at the LHC. The energy resolution of pions in the energy range from 10 to 300 GeV at an incident angle a of about 12 degrees is well described by the expression sigma/E = ((41.9 +/- 1.6)%/root E + (1.8 +/- 0.1)%)circle plus(1.8 +/- 0.1)/E, where E is in GeV. The response to electrons and muons was evaluated. Shower profiles, shower leakage and the angular resolution of hadronic showers were also studied. Results are compared with those from the previous beam test.
|
|
| 3. |
- Akhmadaliev, S., et al.
(författare)
-
Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method
- 2002
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 480:03-feb, s. 508-523
-
Tidskriftsartikel (refereegranskat)abstract
- 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 e/h 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 +/-1% of the true values and the fractional energy resolution is [(58+/-3)%/rootE+(2.5+/-0.3)%]circle plus(1.7+/-0.2)/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74+/-0.04 and agrees with the prediction that e/h > 1.66 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.
|
|
