| 1. |
- Amann, F., et al.
(författare)
-
A search for murarregamma at the level of 10-13
- 1991
-
Ingår i: Proceedings of the 25th International Conference on High Energy Physics. - 9810024347 ; , s. 1070-1071
-
Konferensbidrag (refereegranskat)abstract
- The MEGA experiment, which is a search for the decay murarregamma with a branching ratio sensitivity of about 10-13, employs highly modular, fast detectors, state-of-the-art electronics, and a staged trigger with on-line filters. The detectors are contained in a 1.5-T solenoidal field produced by a superconducting magnet. Positrons are confined to the central region and are measured by a set of thin MWPCs. Photons are measured by one of four layers of pair spectrometers in the outer region. Most aspects of the design have been validated in engineering runs; data taking will begin in 1990 with much of the electron arm and one pair spectrometer layer installed.
|
|
| 2. |
- Anne, R., et al.
(författare)
-
Dissociation Reactions of the Be-11 One-Neutron Halo - the Interplay between Structure and Reaction-Mechanism
- 1993
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 304:1-2, s. 55-59
-
Tidskriftsartikel (refereegranskat)abstract
- The angular distributions of the forward neutrons in the exclusive (Be-10 + n) channel have been measured. They can be accounted for quantitatively and without free parameters in terms of Coulomb and diffraction dissociation. The results show that the transverse momentum distributions result from an interplay between the tail of the wave function (the halo) and the reaction mechanism.
|
|
| 3. |
- Anne, R., et al.
(författare)
-
Exclusive and Restricted-Inclusive Reactions Involving the Be-11 One-Neutron Halo
- 1994
-
Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 575:1, s. 125-154
-
Tidskriftsartikel (refereegranskat)abstract
- Reactions of a 41 MeV/u beam of the radioactive halo nucleus Be-11 have been studied with a counter telescope coupled to an array of neutron detectors covering angles up to 97-degrees. The technique allows to determine single-neutron inclusive and exclusive angular distributions. The targets (Be, Ti and Au) were chosen to illustrate the relative roles played by nuclear and Coulomb mechanisms. The channels leading to Be-10, the dissociation channels, correspond to impact parameters larger than the sum of the radii of the target and the Be-10 core. It is shown that for the dissociation process it is possible to account almost quantitatively for the integral, single- and double-differential cross sections from models without free parameters including the Coulomb, Serber and Glauber (diffraction-dissociation) mechanisms. The neutron distributions from the nondissociative reaction channels show little individuality and it is convenient to group them together as the channel ''neutron plus anything different from Be-10''. We refer to these as ''restricted-inclusive'' reactions. These seem to be a promising tool for obtaining accurate information on the halo wave function in momentum coordinates.
|
|
| 4. |
|
|
| 5. |
- Bengtsson, G. J, et al.
(författare)
-
Determination of Radiative Lifetimes In Neutral Nitrogen Using Short Laser-pulses From A Distributed Feedback Dye-laser
- 1991
-
Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 22:1, s. 397-399
-
Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for two short-lived states in neutral nitrogen. Following photodissociation and two-photon excitation employing the same UV source, excitation to higher states was performed with a distributed feedback dye laser (DFDL). The lifetimes were found to be tau(2p2 4d4D7/2) = 17(3) ns and tau(2p2 5s4P5/2) = 22(3) ns.
|
|
| 6. |
- Borge, M. J. G., et al.
(författare)
-
Beta-Decay to the Proton Halo State in F-17
- 1993
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 317:1-2, s. 25-30
-
Tidskriftsartikel (refereegranskat)abstract
- In the first experiment at the newly constructed ISOLDE Facility the first-forbidden beta-decay of Ne-17 into the first excited state of F-17 has been measured. It is a factor two faster than the corresponding mirror decay and thus gives one of the largest recorded asymmetries for beta decays feeding bound final states. Shell-model calculations can only reproduce the asymmetry if the halo structure of the F-17 state is taken into account.
|
|
| 7. |
- Borge, M. J. G., et al.
(författare)
-
Super-Allowed Beta-Decay of Nuclei at the Drip-Line
- 1991
-
Ingår i: Zeitschrift fur Physik A Hadrons and Nuclei. - 1431-5831 .- 0939-7922. ; 340:3, s. 255-261
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the continuous particle spectra following the beta decay of the neutron-rich nuclei that terminate the mass 6, 8, 9 and 11 isobaric chains. Strong beta transitions feeding the very top of the spectrum are found systematically. The favoured states are within a few MeV of the energy of the initial state. This phenomenon seems to be linked to the occurrence of a di-neutron structure or neutron halo in the drip-line nuclei.
|
|
| 8. |
- Hansen, Ole, et al.
(författare)
-
Effects of carvedilol on the metabolic, hemodynamic, and electrocardiographic responses to increased plasma epinephrine in normal subjects
- 1994
-
Ingår i: Journal of Cardiovascular Pharmacology. - 1533-4023. ; 24:6, s. 853-859
-
Tidskriftsartikel (refereegranskat)abstract
- To study the effects of the new vasodilating beta-blocking agent carvedilol on a variety of metabolic, hemodynamic, and ECG parameters of importance for the clinical outcome of acute myocardial infarction (AMI), we infused epinephrine (EPI) in healthy male volunteers on two separate occasions to serum concentrations of the same level reached in AMI. Before the EPI infusions, the volunteers were pretreated for 2 weeks with either carvedilol or placebo in randomized order. EPI caused significant decreases in serum levels: S-potassium (0.62 mM), S-magnesium (0.07 mM), S-calcium (0.12 mM), and S-phosphate (0.26 mM). After pretreatment with carvedilol, the decreases in S-calcium and S-phosphate were partly prevented and those in S-potassium and S-magnesium were completely inhibited. Short-term treatment with carvedilol significantly decreased S-insulin and serum C-peptide and significantly attenuated the EPI-induced increase in B-glucose observed after placebo. The EPI infusion significantly increased serum concentrations of free fatty acids and glycerol. These increases were significantly attenuated by carvedilol, whereas carvedilol had no significant affects of a variety of other lipid variables. EPI infusion caused a significant (p < 0.01) increase in systolic blood pressure (SBP) from 124.8 +/- 8.1 to 135.8 +/- 12.5 mm Hg and an increase in heart rate (HR) from 71.0 +/- 11.5 to 77.2 +/- 12.2, resulting in a significant increase in rate-pressure product (RPP). This estimate of cardiac work was significantly (p < 0.05) reduced by pretreatment with carvedilol.(ABSTRACT TRUNCATED AT 250 WORDS)
|
|
| 9. |
- Hansen, Staffan, et al.
(författare)
-
The Crystal Structure of Sb0.92V0.92O4, Determined by Neutron and Dual Wavelength X-ray Powder Diffraction
- 1993
-
Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596. ; 102:2, s. 340-348
-
Tidskriftsartikel (refereegranskat)abstract
- A phase of approximate composition SbVO4 has been reported in the literature as a key component in new catalysts for the ammoxidation of propane to acrylonitrile. Sb0.92V0.92O4 was prepared by heating equimolar amounts of Sb2O3 and V2O5 in air at 1073 K for 2 hr. The chemical composition was determined by thermogravimetry and energy dispersive X-ray microanalysis. The crystal structure at 293 K was determined, from three powder diffraction data sets recorded with CuKα1, MoKα, and 1.040(1)-Å neutron radiation, using the Rietveld method. Crystal data: Sb0.92V0.92O4, Z = 1, a = 4.625(4), c = 3.040(2) Å, tetragonal space group P 42/mnm, Mr = 222.87, Dcalc = 5.69 g/cm3. All three data sets yield a cation deficient rutile structure and final profile R-values of 3.5, 6.3, and 3.5%. Bond valence sums, calculated from the experimentally determined bond lengths, indicate the oxidation states to be Sb5+ and V3+/V4+, leading to the formula Sb5+0.92V3+0.28V4+0.64□0.16O4 (the square denotes metal ion vacancies). Bond valence calculations also suggest that OSb2□ is the most favorable configuration for an oxygen associated with a metal vacancy.
|
|
| 10. |
|
|
