| 1. |
- Bargholtz, Chr., et al.
(författare)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 2. |
- Bargholtz, Chr., et al.
(författare)
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The WASA detector facility at CELSIUS
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
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Tidskriftsartikel (refereegranskat)abstract
- The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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| 3. |
- Bashkanov, M., et al.
(författare)
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Double-Pionic Fusion of Nuclear Systems and the "ABC" Effect : Approaching a Puzzle by Exclusive and Kinematically Complete Measurements
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 052301-
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Tidskriftsartikel (refereegranskat)abstract
- The ABC effect-a puzzling low-mass enhancement in the pi pi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn -> d pi(0)pi(0) at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pi pi)(I=L=0) channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a Delta Delta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.
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| 4. |
- Bashkanov, M., et al.
(författare)
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Measurement of the slope parameter for the η → 3π0 decay in the pp → ppη reaction
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 048201-
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Tidskriftsartikel (refereegranskat)abstract
- The CELSIUS-WASA setup is used to measure the 3π0 decay of η mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter α yielding α = −0.026 ± 0.010(stat) ± 0.010(syst). This value is compared to recent experimental results and theoretical predictions.
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| 5. |
- Berlowski, M., et al.
(författare)
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Measurement of eta meson decays into lepton-antilepton pairs
- 2008
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:3, s. 032004-
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Tidskriftsartikel (refereegranskat)abstract
- A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta -> e(+)e(-)e(+)e(-) events are reported with a background of 1.3 +/- 0.2 events. This allows to set an upper limit to the branching ratio of 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
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| 6. |
- Bock, David, 1976, et al.
(författare)
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Explorative analysis of spatial aspects on the Swedish influenza data
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The spatial aspects on the Swedish influenza data are analyzed. During the influenza period, reports on laboratory diagnosed cases and influenza-like-illness are obtained from viral and microbiological laboratories and from sentinel physicians, respectively, in different regions of Sweden. Information about the spatio-temporal patterns might give insight in the way the influenza spreads over Sweden. It might also be used in automated surveillance systems for outbreak and peak detection of the influenza. We describe the regional patterns in Swedish influenza data in different ways. Several natural hypotheses about geographical patterns are examined but can not be verified as consistent over the years. However, we find that, for a group of large cities, the outbreak of the influenza occurs at least four weeks earlier than for the rest of Sweden. The possibilities to utilize this in surveillance systems are briefly discussed.
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| 7. |
- Bock, David, 1976, et al.
(författare)
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Exploratory analysis of spatial aspects on the Swedish influenza
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The spatial aspects on the Swedish influenza data are analyzed. During the influenza period, reports on laboratory diagnosed cases and influenza-like-illness are obtained from viral and microbiological laboratories and from sentinel physicians, respectively, in different regions of Sweden. Information about the spatio-temporal patterns might give insight in the way the influenza spreads over Sweden. It might also be used in automated surveillance systems for outbreak and peak detection of the influenza. We describe the regional patterns in Swedish influenza data in different ways. Several natural hypotheses about geographical patterns are examined but can not be verified as consistent over the years. However, we find that, for a group of large cities, the outbreak of the influenza occurs at least four weeks earlier than for the rest of Sweden. The possibilities to utilize this in surveillance systems are briefly discussed.
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| 8. |
- Enoksson, Staffan, et al.
(författare)
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Marked Re-Utilization of Free Fatty Acids During Activated Lipolysis in Human Skeletal Muscle.
- 2005
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 90:2, s. 1189-1195
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Tidskriftsartikel (refereegranskat)abstract
- Release of glycerol and free fatty acids (FFA) was investigated in human skeletal muscle strips. In the basal state, glycerol and FFA were released at almost equimolar rates (0.3 nmol/ng tissue.90 min). A nonselective beta-adrenoceptor agonist, isoprenaline, caused a concentration-dependent stimulation of glycerol release, whereas FFA release was unaffected. Basal and isoprenaline-induced glycerol release correlated positively with the age of the donors (r = 0.5, P < 0.005) but not with their body mass index (P > or = 0.4). Biochemical experiments with hormone-sensitive lipase (HSL) showed that most enzyme activity was both in the cytosol and mitochondrial fraction and that it constituted the common long and active form of the protein. Electron microscopy studies in rat skeletal muscle using labeled highly specific HSL antibodies verified the cytosolic location of HSL and, furthermore, indicated an accumulation of HSL-adjoining mitochondria. These results suggest that FFA produced in myocytes during catecholamine-induced lipolysis are retained by the muscle and, therefore by inference, reused. It is conceivable that efficient hydrolysis of acylglycerol by HSL located in the cytosol as well as near the mitochondria may facilitate mitochondrial FFA oxidation. In addition, muscle lipolysis activity increases during aging and may be independent of total body fat.
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| 9. |
- Frisén, Marianne, 1943, et al.
(författare)
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MULTIVARIATE CONTROL CHARTS FOR SURVEILLANCE OF OUTBREAKS
- 2009
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Ingår i: International Conference on Frontiers of Interface between Statistics and Sciences 30 Dec 2009-2 Jan 2010, Hyderabad, India.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
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| 11. |
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| 12. |
- Keros, Victoria, et al.
(författare)
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Vitrification versus controlled-rate freezing in cryopreservation of human ovarian tissue
- 2009
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Ingår i: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 24:7, s. 1670-1683
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Controlled-rate freezing of ovarian cortical tissue for preservation of fertility among young women facing chemo- or radio-therapy is a widely accepted procedure. To improve the method for cryopreservation of ovarian tissue, particularly the stroma, we carried out a systematic comparison of vitrification versus slow programmed freezing. METHODS: Ovarian tissue from 20 women, donated during Caesarean section, was used for parallel comparison of survival and detailed light and electron microscopic (EM) morphology of oocytes, granulosa cells and ovarian stroma after freezing (slow freezing and vitrification), thawing and 24-h culture. Using tissue obtained from the same patient, we compared four cryopreservation protocols and fresh tissue. The cryoprotectants used in slow freezing were 1,2-propanediol (PrOH)-sucrose and ethylene glycol (EG)-sucrose. For vitrification, tissues were incubated for 5 or 10 min in three solutions containing a combination of dimethyl sulphoxide (DMSO), PrOH, EG and polyvinylpyrrolidone (PVP). RESULTS: Cryopreservation using controlled-rate freezing and vitrification preserved the morphological characteristics of ovarian tissue generally well. As revealed by morphological analysis, particularly EM, the ovarian stroma was significantly better preserved after vitrification than after slow freezing (P < 0.001). The follicles were similarly preserved after all freezing methods. CONCLUSIONS: Vitrification using a combination of PrOH, EG, DMSO and PVP was comparable to slow freezing in terms of preserving follicles in human ovarian tissue. Ovarian stroma had significantly better morphological integrity after vitrification than after controlled-rate freezing.
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| 13. |
- Nilsson, Marita, et al.
(författare)
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Catalytic properties of Pd supported on ZnO/ZnAl2O4/Al2O3 mixtures in dimethyl ether autothermal reforming
- 2009
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 86:02-jan, s. 18-26
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic properties of Pd supported on mixtures of zinc oxide, zinc aluminate, and alumina, prepared from gamma-alumina and zinc nitrate, were studied for autothermal reforming (ATR) of dimethyl ether (DME). The performance of the catalysts was tested in a small-scale reactor, using cordierite monoliths as substrate. The catalysts exhibited high activity and generated hydrogen-rich product gases with CO concentrations below 5 vol.% in the temperature range between 350 and 450 degrees C (at O-2:DME = 0.7, H2O:DME = 2.5, and GHSV = 15000 h(-1)). The highest DME conversion was obtained for a catalyst in which the support comprised mainly ZnAl2O4. Physical mixing of the catalysts with gamma-Al2O3 resulted in increased DME conversion but a lowering of the CO2 selectivity. The catalysts were characterized by CO chemisorption, liquid nitrogen adsorption, temperature-programmed desorption of ammonia, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. It was found that decreasing surface area and decreasing number of acid sites, caused by thermal treatment during generation of the supports, did not affect the activity negatively. The high CO2 selectivity of the catalysts was correlated with PdZn alloy formation.
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| 14. |
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| 15. |
- Pauly, C., et al.
(författare)
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The pp→ppπππ reaction channels in the threshold region
- 2007
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 649:2-3, s. 122-127
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Tidskriftsartikel (refereegranskat)abstract
- The cross section for direct neutral and charged three pion production in pp interactions was measured at excess energies in the range 160–216 MeV. That comprises the first measurement of the pp→ppπ0π0π0 reaction and the direct comparison with the pp→ppπ+π−π0 process. The experiment was performed above the η meson production threshold and the cross section could be directly normalized to the cross section of the pp→ppη reaction, with the η decaying into 3 pions. Since the same final states are selected, the measurement has a low systematical error. The measured cross section ratio σ(pp→ppπ+π−π0)/σ(pp→ppπ0π0π0) is compared to predictions of dominance of different isobars in the intermediate state.
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| 16. |
- Pettersson, Henrik, et al.
(författare)
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eta PRODUCTION IN PROTON-PROTON COLLISIONS AT 72 MeV EXCESS ENERGY
- 2009
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Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 24:2-3, s. 446-449
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Tidskriftsartikel (refereegranskat)abstract
- The production of eta mesons at an excess energy of 72 MeV has been studied in the reaction pp -> pp(eta)gamma gamma. It is shown that a simple model with Pp. final states included reproduces observed differential distributions better than the same model restricted to Ss, Sd and Ds final states. The strong influence of the Pp states could be taken as an indication of rho dominance within an one boson exchange model for the excitation of N*(1535).
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| 17. |
- Pettersson, Hanna, et al.
(författare)
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Metabolism of a novel side chain modified Delta 8(14)-15-ketosterol, a potential cholesterol lowering drug : 28-hydroxylation by CYP27A1
- 2008
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981 .- 1879-2618. ; 1781:8, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- The synthetic inhibitors of sterol biosynthesis, 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one and 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one, are of interest as potential cholesterol lowering drugs. Rapid metabolism of synthetic 15-ketosterols may lead to a decrease, or loss, of their potency to affect lipid metabolism. 3beta-Hydroxy-5alpha-cholest-8(14)-en-15-one is reported to be rapidly side chain oxygenated by rat liver mitochondria. In an attempt to reduce this metabolism, the novel side chain modified 15-ketosterol 3beta-Hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one was synthesized. We have examined the metabolism by recombinant human CYP27A1 of this novel side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one and compared the rate of metabolism with that of the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. Both sterols were found to be efficiently metabolized by recombinant human CYP27A1. None of the two 15-ketosterols was significantly metabolized by microsomal 7alpha-hydroxylation. Interestingly, CYP27A1-mediated product formation was much lower with the side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one than with the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. A surprising finding was that this novel side chain modified sterol was metabolized mainly in the C-28 position by CYP27A1. The data on 28-hydroxylation by human CYP27A1 provide new insights on the catalytic properties and substrate specificity of this enzyme. The finding that 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one with a modified side chain is metabolized at a dramatically slower rate than the previously described 15-ketosterol with unmodified side chain may be important for future development of synthetic cholesterol lowering sterols.
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| 18. |
- Pettersson, Hanna, 1968-
(författare)
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Steroid-Metabolizing Cytochrome P450 (CYP) Enzymes in the Maintenance of Cholesterol and Sex Hormone Levels
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The enzymes CYP27A1 and CYP7B1 are widely expressed in various human tissues and perform catalytic reactions in cholesterol homeostasis and endocrine signaling. We have investigated the metabolism of a synthetic oxysterol. In this study, we show that CYP27A1 is the enzyme responsible for a 28-hydroxylation of this oxysterol and that the rate of CYP27A1-mediated metabolism is relatively slow. This may give an explanation for the prolonged inhibitory effects on cholesterol biosynthesis that have been shown for this oxysterol. The current study contributes to the knowledge of synthetically produced oxysterols and their potential use as cholesterol lowering drugs. In two studies we investigated CYP7B1-mediated metabolism of different sex hormones. Our data indicate that CYP7B1 may carry out a previously unknown catalytic reaction involving an androgen. Taken together the data suggest that varying steroid concentrations in cells and tissues may be important for CYP7B1-dependent metabolism of sex hormones and sex hormone precursors. CYP7B1-mediated hydroxylation of sex hormones may influence the cellular levels of these steroids and may be a potential pathway for elimination of the steroids from the cell. Some known CYP7B1 substrates are agonists for ERα and ERβ but the reported role(s) of CYP7B1 for ER action are not fully understood. In the last study we investigated the role(s) of CYP7B1-mediated metabolism for ER-mediated action. Our data indicate that CYP7B1-mediated conversion of steroids that affect ER-mediated response into their 7α-hydroxymetabolites will result in loss of action. This indicates that CYP7B1 may have an important role for regulation of ER-mediated processes in the body. In summary, results from this thesis contribute to the knowledge on the metabolism of synthetic oxysterols of potential use as cholesterol lowering drugs and the role(s) of CYP7B1-mediated metabolism for processes related to the functions of sex hormones.
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| 19. |
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| 20. |
- Pettersson, Kjell, 1948
(författare)
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On Unimodal Regression in the Exponential Family
- 2009
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Ingår i: Communications in Statistics - Theory and Methods. - : Informa UK Limited. - 0361-0926 .- 1532-415X. ; 38:9, s. 1526-1538
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we discuss statistical methods for curve-estimation under the assumption of unimodality for variables with distributions belonging to the two-parameter exponential family with known or constant dispersion parameter. An important special case is a one-parameter distribution. We suggest a nonparametric method based on monotonicity properties. The method is applied to Swedish data on laboratory verified diagnoses of influenza and data on inflation from an episode of hyperinflation in Bulgaria.
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| 21. |
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| 22. |
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| 23. |
- Thörngren Engblom, Pia, et al.
(författare)
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Anisotropy in the pion angular distribution of the reaction pp -> pp pi(0) at 400 MeV
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:1, s. 011602-
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pp -> pp pi(0) was studied with the WASA detector at the CELSIUS storage ring. The center of mass angular distribution of the pi(0) was obtained by detection of the gamma decay products together with the two outgoing protons and found to be anisotropic with a negative second derivative slope, in agreement with the theoretical predictions from a microscopic calculation.
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