| 1. |
- Akimov, D., et al.
(författare)
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Physics with WASA and PROMICE
- 1994
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Ingår i: Physics with GeV-particle beams, Juelich 1994. ; , s. 519-530
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
- Calén, H., et al.
(författare)
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Deuteron breakup by 1.15 GeV protons and excitation of the Δ isobar
- 1993
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 303:1-2, s. 10-15
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Tidskriftsartikel (refereegranskat)abstract
- The pd→npp reaction has been measured using circulating 1.15 GeV protons, a gas jet target and scintillation detectors selecting scattered protons with energy above 30 MeV. The distribution of the two-proton invariant mass has a maximum at 2.13 ± 0.01 GeV/c2 and a width of 130 ± 10 MeV/c2 (FWHM). We see no evidence of narrow (Γ < 30 MeV/c2) peaks in the phase-space region selected. The mass of X, excited in the pN→nX elementary process, is 40 MeV/c2 smaller than the mass of a real Δ isobar.
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| 4. |
- Calén, H, et al.
(författare)
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Deuteron breakup in the Δ-isobar region
- 1993
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Ingår i: Physica Scripta. - : Institute of Physics (IOP). - 0031-8949 .- 1402-4896. ; 48:1, s. 86-91
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Tidskriftsartikel (refereegranskat)abstract
- The pd → npp charge exchange reaction has been studied at 1.15 GeV incident proton energy in a selected kinematical region. The distributions of two-proton invariant mass Mpp, of angle of a single proton and the differential cross section dσ/dt of the (p, n) reaction are presented and compared with model predictions corrected for the acceptance of the experimental apparatus. We see no evidence of narrow (Γ < 30 MeV/c2) peaks in the Mpp interval 2.1-2.3 GeV/c2. The production of an intermediate Δ isobar in the primary (p, n) charge exchange and its subsequent absorption in a final state ΔN → pp process together with the background from quasi-free charge exchange scattering reasonably reproduces the general trends of the data.
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| 5. |
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| 6. |
- Gustafsson, L., et al.
(författare)
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A data acquisition system for the wide angle shower apparatus (WASA)
- 1993
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Ingår i: 1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference. - 0780314875 ; , s. 518-521
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Konferensbidrag (refereegranskat)abstract
- A new data acquisition system based on concepts such as data switches and multiple-processors is described. The main topic is how data coming from a multicrate front-end in CAMAC, VME and FASTBUS are transported over different links to a buffer-matrix data switch and further into a farm of microprocessors. Modularity, scalability and multilevel data monitoring are important parts of the design goals that are presented. The system is intended for use in an experiment searching for rare events where high interaction rates are necessary and where a fast and selective trigger is difficult to define. Other experimental constraints, the trigger logical structure and the performance of the data acquisition are also described.
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| 7. |
- Gustafsson, L., et al.
(författare)
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A data acquisition system for the wide angle shower apparatus (WASA)
- 1994
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 41:4, s. 1155-1158
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Tidskriftsartikel (refereegranskat)abstract
- A new data acquisition system based on concepts such as data switches and multiple-processors is described. The main topic is how data coming from a multicrate front-end in CAMAC, VME and FASTBUS are transported over different links to a buffer-matrix data switch and further into a farm of microprocessors. Modularity, scalability and multilevel data monitoring are important parts of the design goals that are presented. The system is intended for use in an experiment searching for rare events where high interaction rates are necessary and where a fast and selective trigger is difficult to define. Other experimental constraints, the trigger logical structure and the performance of the data acquisition are also described.
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| 8. |
- Johansson, LB-Å, et al.
(författare)
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Phase equilibria and formation of vesicles of dioleoylphosphatidylcholine in glycerol/water mixtures
- 1993
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736 .- 1879-2642. ; 1149, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- The lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) forms a lamellar liquid crystalline phase (La) in arbitrary mixtures of glycerol and water. The phase has been characterized by means of X-ray diffraction, 3IP-NMR spectroscopy and differential scanning calorimetry (DSC). In the La state, and for DOPC concentrations greater than 50% (w/w), the thickness of the lipid bilayer decreases, while the area of the polar head group increases with increasing glycerol concentration. The phase transition from gel to La state occurs in the range of 240 to 260 K. Contrary to a previous (McDaniel, R.V., McIntosh, T.J. and Simon, S.A. (1983) Biochim. Biophys. Acta 731, 97) study of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) we find that in the gel state, the thickness of the DOPC lipid bilayer is greater than that in the La state. This suggests that in the gel state, the lipid acyl chains of DOPC are in extended configuration. The lamellar phase reaches its maximum swelling at about 50% (w/w) of DOPC. At lower DOPC concentrations a two-phase system is formed where the lamellar phase exists in equilibrium with excess of solvent. Unilamellar vesicles can be prepared from a diluted suspension of the lamellar phase either by using the sonicator or extruder technique. We show this by means of 3IP-NMR, EPR and fluorescence spectroscopy. The mean radius of the vesicles, prepared by a sonicator, has been determined at different glycerol/water mixtures. It is found to decrease continously from 100 A at 100% water to a minimum of 75 Å at about 50% water in the solvent mixture. By further decreasing the water content in the solution, the radius rapidly increases, and a mean radius of 450 Å is estimated at a water content of 10%. The rotational relaxation times of a fluorescent probe and two EPR spin probes, solubilized in DOPC vesicles, have been measured at different glycerol/water mixtures. It is found that the rotational rates are always much slower in the systems containing glycerol.
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