| 1. |
- Adlarson, Patrik, et al.
(author)
-
Search for eta-mesic He-4 with the WASA-at-COSY detector
- 2013
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 035204-
-
Journal article (peer-reviewed)abstract
- An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively.
|
|
| 2. |
- Akimov, D., et al.
(author)
-
Physics with WASA and PROMICE
- 1994
-
In: Physics with GeV-particle beams, Juelich 1994. ; , s. 519-530
-
Conference paper (peer-reviewed)
|
|
| 3. |
- Keleta, S, et al.
(author)
-
Exclusive measurement of two-pion production in the dd -> He-4 pi pi reaction
- 2009
-
In: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 825:1-2, s. 71-90
-
Journal article (peer-reviewed)abstract
- The results from the first kinematically complete measurement of the dd -> He-4 pi pi reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar pi pi-invariant mass distributions appearing in double pion production in light ion collisions, the so-called ABC effect. The measurements were performed at the incident deuteron energies of 712 MeV and 1029 MeV. with the WASA detector assembly at CELSIUS in Uppsala, Sweden. We report the observation of a characteristic enhancement at low pi pi-invariant mass at 712 MeV, the lowest energy yet. At the higher energy, in addition to confirming previous experimental observations, Our results reveal a strong angular dependence of the pions in the overall centre of mass system. The results are qualitatively reproduced by a theoretical model, according to which the ABC effect is described as resulting from a kinematical enhancement in the production of the pion pairs from two parallel and independent NN -> d pi sub-processes. (C) 2009 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Schonning, K., et al.
(author)
-
The pd -> He-3 eta pi(0) reaction at T-p=1450 MeV CELSIUS/WASA Collaboration
- 2010
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 685:1, s. 33-37
-
Journal article (peer-reviewed)abstract
- The cross section for the pd -> He-3 eta pi(0) reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring. The He-3 was detected in coincidence with four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Delta(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant mass distributions Of all three pairs of final particles are well reproduced by a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the pi(0) momentum in the He-3 pi(0) system.
|
|
| 5. |
- Schönning, Karin, et al.
(author)
-
Polarisation of the omega meson in the pd -> He-3 omega reaction at 1360 and 1450 MeV
- 2008
-
In: Physics Letters B. - elsevier : Elsevier BV. - 0370-2693 .- 1873-2445. ; 668:4, s. 258-262
-
Journal article (peer-reviewed)abstract
- The tensor polarisation of omega mesons produced in the pd -> He-3 omega reaction has been studied at two energies near threshold. The 3 He nuclei were detected in coincidence with the pi(0)pi(+)pi(-) or pi(0)gamma decay products of the omega. in contrast to the case of phi-meson production, the omega mesons are found to be unpolarised. This brings into question the applicability of the Okubo-Zweig-lizuka rule when comparing the production of vector mesons in low energy hadronic reactions.
|
|
| 6. |
- Schönning, Karin, et al.
(author)
-
Production of eta and 3 pi mesons in the pd -> (HeX)-He-3 reaction at 1360 and 1450 MeV
- 2010
-
In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 45:1, s. 11-21
-
Journal article (peer-reviewed)abstract
- The cross-sections of the pd -> He-3 eta, pd -> He-3 pi(0)pi(0)pi(0) and pd -> He-3 pi(+)pi(-)pi(0) reactions have been measured at the beam kinetic energies T-p = 1360 MeV and T-p = 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the differential cross-section d sigma/d Omega of the eta meson in the pd -> He-3 eta reaction shows a strong forward-backward asymmetry in the CMS. The ratio between the pd -> He-3 pi(+)pi(-)pi(0) and pd -> He-3 pi(0)pi(0)pi(0) cross-sections has been analysed in terms of isospin amplitudes. The reconstructed invariant-mass distributions of the pi pi, He-3 pi and (3)He2 pi systems provide hints on the role of nucleon resonances in the 3 pi production process.
|
|
| 7. |
- Schönning, Karin, et al.
(author)
-
Production of the omega meson in the pd -> He-3 omega reaction at 1450 MeV and 1360 MeV
- 2009
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:4, s. 044002-
-
Journal article (peer-reviewed)abstract
- The production of omega mesons in the pd -> He-3 omega reaction has been studied at two energies near the kinematic threshold, T-p = 1450 MeV and T-p = 1360 MeV. The differential cross section was measured as a function of the omega c.m. angle at both energies over the whole angular range. Whereas the results at 1360 MeV are consistent with isotropy, strong rises are observed near both the forward and backward directions at 1450 MeV. Calculations made using a two-step model with an intermediate pion fail to reproduce the shapes of the measured angular distributions and also underestimate the total cross sections.
|
|
| 8. |
- Bilger, R, et al.
(author)
-
Cross sections of the pp -> pp pi(0) reaction between 310 and 425 MeV
- 2001
-
In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 693:3-4, s. 633-662
-
Journal article (peer-reviewed)abstract
- Extensive kinematically complete measurements of the pp --> pp pi (0) reaction have been made at six beam energies: 310, 320, 340, 360, 400, and 425 MeV. Angles and energies of both final-state protons are extracted from the forward detector system of the
|
|
| 9. |
- Bilger, R, et al.
(author)
-
Spectator tagging in quasi-free pn-reactions on deuterium at PROMICE/WASA, CELSIUS
- 2000
-
In: Nuclear Physics A. - : Elsevier Science B.V. Holland. ; , s. 1053c-1056c
-
Conference paper (peer-reviewed)abstract
- A set of silicon detectors has been added to the PROMICE/WASA (P/W) experiment at CELSIUS. These detectors have been used for spectator-proton tagging in proton deuteron collisions to investigate proton-neutron reactions at intermediate energies. The perf
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Calen, H, et al.
(author)
-
Threshold structure of the quasifree p+n -> d+eta reaction
- 1998
-
In: PHYSICAL REVIEW LETTERS. - : AMERICAN PHYSICAL SOC. - 0031-9007. ; 80:10, s. 2069-2072
-
Journal article (peer-reviewed)abstract
- The quasifree p + n --> d + eta reaction cross section has been measured at the threshold using 1295 MeV protons in the CELSIUS storage ring and an internal cluster-jet deuterium target. The kinematics is chosen such that the target proton can be assumed
|
|
| 14. |
- Greiff, J, et al.
(author)
-
Pion production in dp -> dN pi reactions with deuteron projectiles - art. no. 064002
- 2000
-
In: PHYSICAL REVIEW C. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 6206:6, s. 4002-
-
Journal article (peer-reviewed)abstract
- Kinematically complete events have been studied for the reactions dp-->dp pi (0) and dp-->dn pi (+) at projectile energies between 437 and 559 MeV. The measurement covers a range of pion momenta eta =p(pi ,c.m.)(max)/m(pi)c from near the production thresh
|
|
| 15. |
- Bright, TB, et al.
(author)
-
Radiative proton capture to discrete states in C-12 at 98 and 176 MeV
- 1996
-
In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 603:1, s. 1-22
-
Journal article (other academic/artistic)abstract
- A high-resolution magnetic pair spectrometer for medium energy photons has been used for studies of the exclusive (p, gamma) reaction on B-11 at 98 and 176 MeV, We present angular distributions of the differential cross section for transitions to the grou
|
|
| 16. |
- Brodowski, W, et al.
(author)
-
Exclusive measurement of pp -> pp pi(+)pi(-) at CELSIUS
- 2000
-
In: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254. ; 31:10-11, s. 2295-2298
-
Journal article (peer-reviewed)abstract
- With the PROMICE/WASA detector setup at CELSIUS the reaction pp --> NN pi pi has been measured in the energy range from 650 to 775 MeV. These data constitute the first exclusive high-statistics measurements on a pure hydrogen target, supplying both differ
|
|
| 17. |
|
|
| 18. |
- Gornov, MG, et al.
(author)
-
A charged particle spectrometer for small-angle experiments
- 1999
-
In: INSTRUMENTS AND EXPERIMENTAL TECHNIQUES. - : PLENUM PUBL CORP. - 0020-4412. ; 42:4, s. 493-499
-
Journal article (other academic/artistic)abstract
- A high-purity germanium spectrometer for detecting long-range charged particles emitted at small angles is described. The spectrometer is intended for investigations of two-body nuclear reactions on the internal targets of the CELSIUS storage ring. It is
|
|
| 19. |
|
|
| 20. |
- Johansson, R, et al.
(author)
-
Measurement of the exclusive D(p,e(+)e(-))He-3 and D(p,gamma)He-3 reactions at 98 and 176 MeV
- 1998
-
In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 641:4, s. 389-400
-
Journal article (peer-reviewed)abstract
- A high resolution magnetic pair spectrometer for medium energy photons has been used for studies of the exclusive (p,e(+)e(-)) and (p, gamma) reactions on deuterium at 98 and 176 MeV. The (p, e(+)e(-)) cross sections, obtained at 40 degrees and 80 degrees
|
|
| 21. |
- Lenoir, Jonathan, et al.
(author)
-
Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe
- 2013
-
In: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 19:5, s. 1470-1481
-
Journal article (peer-reviewed)abstract
- Recent studies from mountainous areas of small spatial extent (<2500km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 4672% of variation in LmT and 9296% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 6065 degrees N and increased with terrain roughness, averaging 1.97 degrees C (SD=0.84 degrees C) and 2.68 degrees C (SD=1.26 degrees C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32 degrees Ckm1) than spatial turnover in growing-season GiT (0.18 degrees Ckm1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.
|
|
| 22. |
- Traneus, E, et al.
(author)
-
First measurement of the exclusive (p,e(+)e(-)) reaction
- 1997
-
In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 613:3, s. 267-281
-
Journal article (other academic/artistic)abstract
- We present the first data on the exclusive (p, e(+)e(-)) reaction in a nucleus. Cross sections for populating the ground state and first excited state in the residual nucleus are presented for the reaction B-11(p, e(+)e(-))C-12 at 98 MeV. The e(+)e(-) mom
|
|
| 23. |
- Wasof, Safaa, et al.
(author)
-
Disjunct populations of European vascular plant species keep the same climatic niches
- 2015
-
In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 24:12, s. 1401-1412
-
Journal article (peer-reviewed)abstract
- Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with strictly disjunct populations and 58 species (16%) of the 358 species with distant populations showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic-alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000-15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time-at least on time scales 104 years or less-seems to be largely valid for arctic-alpine plants.
|
|
| 24. |
|
|
