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Fransson, Kjell
Alternative names
Publications (10 of 95) Show all publications
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bass, S. D., Berlowski, M., . . . Zurek, M. (2020). Search for η mesic 3He with the WASA-at-COSY facility in the pd -> 3He2γ and pd -> 3He6γ  reaction. Physics Letters B, 802, Article ID 135205.
Open this publication in new window or tab >>Search for η mesic 3He with the WASA-at-COSY facility in the pd -> 3He2γ and pd -> 3He6γ  reaction
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2020 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 802, article id 135205Article in journal (Refereed) Published
Abstract [en]

We report on the experimental search for the bound state of an eta meson and He-3 nucleus performed using the WASA-at-COSY detector setup. In order to search for the eta-mesic nucleus decay, the pd -> (3)He2(gamma) and pd -> (3)He6 gamma channels have been analysed. These reactions manifest the direct decay of the ti meson bound in a He-3 nucleus. This non-mesonic decay channel has been considered for the first time. When taking into account only statistical errors, the obtained excitation functions reveal a slight indication for a possible bound state signal corresponding to a He-3-eta nucleus width Gamma above 20 MeV and binding energy B-s between 0 and 15 MeV. However, the determined cross sections are consistent with zero in the range of the systematic uncertainty. Therefore, as final result we estimate only the upper limit for the cross section of the eta-mesic He-3 nucleus formation followed by the eta meson decay which varies between 2 nb and 15 nb depending on possible bound state parameters.

Keywords
eta-mesic nuclei, eta-meson
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-409716 (URN)10.1016/j.physletb.2020.135205 (DOI)000515091400060 ()
Available from: 2020-04-27 Created: 2020-04-27 Last updated: 2020-04-27Bibliographically approved
Li, H., Jobs, M., Santiago Kern, R., Goryashko, V. A., Hermansson, L., Bhattacharyya, A., . . . Ruber, R. (2019). Characterization of a beta=0.5 double spoke cavity with a fixed power coupler. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 927, 63-69
Open this publication in new window or tab >>Characterization of a beta=0.5 double spoke cavity with a fixed power coupler
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2019 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 927, p. 63-69Article in journal (Refereed) Published
Abstract [en]

ESS, the European Spallation Source, will adopt a single family of double spoke cavities for accelerating the beam from the normal conducting section to the first family of the elliptical superconducting cavities. It will be the first double spoke cavities in the world to be commissioned for a high power proton accelerator. The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at Uppsala University. A pulse-mode test stand based on a self-excited loop was used in this test. The qualification of the cavity package involves a double-spoke superconducting cavity, a fixed fundamental power coupler, tuner, a low-level radiofrequency (LLRF) system and a high-power radiofrequency (RF) station. The test represents an important verification milestone before the module assembly. This cavity had unfortunately a high dynamic loss of 12W @ 9 MV/m, where potential causes for such a high value have been studied and corresponding suggestions are listed. This paper presents the test configuration, RF conditioning history, first high power performance and experience of this cavity package.

Keywords
Double spoke cavity, High power test, Self-excited loop
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-382240 (URN)10.1016/j.nima.2019.02.003 (DOI)000462142700008 ()
Funder
EU, Horizon 2020, 730871
Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Santiago-Kern, R., Li, H., Miyazaki, A., Gajewski, K., Hermansson, L., Fransson, K., . . . Ruber, R. (2019). Cryogenic Performance of the Spoke Prototype Cryomodule for ESS.
Open this publication in new window or tab >>Cryogenic Performance of the Spoke Prototype Cryomodule for ESS
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2019 (English)Report (Other academic)
Abstract [en]

This report gives an account of all the cryogenic tests performed on the prototype spoke cryomodule, which housed Romea (cavity 1) and Giulietta (cavity 2) with all their ancillary equipment, such as static and dynamic heat loads under different circumstances.

Publisher
p. 48
Series
FREIA Report ; 2019/05
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-397744 (URN)
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-11-26Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2019). Examination of the production of an isotensor dibaryon in the pp -> pp pi(+)pi(-) reaction. Physical Review C: Covering Nuclear Physics, 99(2), Article ID 025201.
Open this publication in new window or tab >>Examination of the production of an isotensor dibaryon in the pp -> pp pi(+)pi(-) reaction
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2019 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 99, no 2, article id 025201Article in journal (Refereed) Published
Abstract [en]

The quasifree pp -> pp pi(+)pi(-) reaction has been measured by means of pd collisions at T-p = 1.2 GeV using the WASA detector setup at COSY enabling exclusive and kinematically complete measurements. Total and differential cross sections have been extracted for the energy region T-p = 1.08-1.36 GeV (root s = 2.35-2.46 GeV) covering thus the regions of N* (1440 ) and Delta(1232)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange as well as isospin relations based on the pp -> pp pi(0)pi(0) data underpredict substantially the measured total cross section. The calculations are also at variance with specific experimental differential cross sections. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+) ) produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong [Phys. Rev. Lett. 13, 815 (1964)] and more recently calculated by A. Gal and H. Garcilazo [Nucl. Phys. A 928, 73 (2014)].

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-377601 (URN)10.1103/PhysRevC.99.025201 (DOI)000457696100003 ()
Available from: 2019-02-26 Created: 2019-02-26 Last updated: 2019-03-07Bibliographically approved
Li, H., Miyazaki, A., Santiago-Kern, R., Hermansson, L., Lofnes, T., Gajewski, K., . . . Ruber, R. (2019). RF Performance of the spoke prototype cryomodule for ESS.
Open this publication in new window or tab >>RF Performance of the spoke prototype cryomodule for ESS
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2019 (English)Report (Other academic)
Abstract [en]

The European spallation source (ESS), as a world-class high power proton accelerator facility, will be the first one to adopt 26 double spoke resonators (DSR) at its low energy section. As a new superconducting accelerating structure, these DSRs are therefore considered as a key technology and challenge of the whole project. They will be the first D SRs in the world to be commissionedfor a high power proton accelerator. As a milestone, the first DSR prototype cryomodule for ESS project was successfully tested at the FREIA Laboratory. In this qualification of the prototype cryomodule, the whole chain of RF station, RF distribution, fundamental power coupler (FPC), DSRs, cold tuning system (CTS) and low level radio frequency (LLRF) system, as well as the testing procedure have been verified on preparation for the industrialized cryomodules. Both cavities in the prototype cryomodule achieved nominal accelerating gradient, with the maximum gradient of 15 MV/m and 10.5 MV/m for cavity 1 and cavity 2 respectively. Based on the calorimetrical method, the dynamic heat load measurement showed that the cavity power consumption is around 0.5 W and therefore the intrinsic quality factor is consistent with the vertical test. This report presents the test configuration, RF conditioning history and first high power performance of this cryomodule.

Publisher
p. 51
Series
FREIA Report ; 2019-08
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-409815 (URN)
Available from: 2020-04-29 Created: 2020-04-29 Last updated: 2020-05-06Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Wilkin, C. (2018). Backward single-pion production in the pd -> He-3 pi(0)reaction with WASA-at-COSY. European Physical Journal A, 54(9), Article ID 149.
Open this publication in new window or tab >>Backward single-pion production in the pd -> He-3 pi(0)reaction with WASA-at-COSY
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, no 9, article id 149Article in journal (Refereed) Published
Abstract [en]

New data on the production of single neutral pions in the pd -> He-3 pi(0) reaction are presented. For fifteen proton beam momenta between p(p) = 1.60GeV/c and p(p) = 1.74 GeV/c, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum.

Place, publisher, year, edition, pages
SPRINGER, 2018
National Category
Astronomy, Astrophysics and Cosmology Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-366738 (URN)10.1140/epja/i2018-12585-3 (DOI)000444638600001 ()
Funder
EU, FP7, Seventh Framework Programme, 283286
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-10Bibliographically approved
Li, H., Santiago-Kern, R., Jobs, M., Hermansson, L., Gajewski, K., Lofnes, T., . . . Ruber, R. (2018). First High Power Test of the ESS High Beta Elliptical Cavity package. Uppsala University
Open this publication in new window or tab >>First High Power Test of the ESS High Beta Elliptical Cavity package
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2018 (English)Report (Other academic)
Abstract [en]

The first high-beta elliptical cavity for ESS project was tested with high power in the HNOSS cryostat at FREIA Laboratory.  This cavity is designed for 704.42 MHz, a pulse mode with 14 Hz repetition rate, up to peak power of 1.5 MW. The qualification of the cavity package in a high power test, involved an elliptical superconducting cavity, a fundamental power coupler, cold tuning system, LLRF system and klystron system, represented an important verification before the module assembly. This report presents the test configuration, RF conditioning history and first high power performance of this cavity package.

Place, publisher, year, edition, pages
Uppsala University, 2018. p. 60
Series
FREIA Report ; 2018/07
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-371627 (URN)
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-09Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2018). Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi(0). Physics Letters B, 781, 645-650
Open this publication in new window or tab >>Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi(0)
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 781, p. 645-650Article in journal (Refereed) Published
Abstract [en]

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd -> He-4 pi(0) using the WASA-at-COSY detector setup at an excess energy of Q = 60 MeV. The determined differential cross section can be parametrized as d sigma/d Omega = a + b cos(2) theta*, where theta* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 +/- 0.46(stat)(-0.8)(+0.32)(syst)) pb/sr and b = (13.1 +/- 2.1(stat)(-2.7)(+1.0)(syst)) pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the A isobar to the dd -> He-4 pi(0) reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Charge symmetry breaking, Deuteron deuteron interactions, Pion production
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-358693 (URN)10.1016/j.physletb.2018.04.037 (DOI)000435653100082 ()
Funder
EU, FP7, Seventh Framework Programme, 227431Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2018). Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?. Physical Review Letters, 121(5), Article ID 052001.
Open this publication in new window or tab >>Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 5, article id 052001Article in journal (Refereed) Published
Abstract [en]

Exclusive measurements of the quasifree pp -> pp pi(+)pi(-) reaction have been carried out at WASA@ COSY by means of pd collisions at T-p = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region T-p = 1.08-1.36 GeV, which is the region of N* (1440) and Delta(123)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+)) produced associatedly with a pion is able to overcome these deficiencies.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-362841 (URN)10.1103/PhysRevLett.121.052001 (DOI)000440415600003 ()30118290 (PubMedID)
Funder
German Research Foundation (DFG), CL 214/3-2
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2018-10-15Bibliographically approved
Adlarson, P., Collaboration, W.-a., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., . . . Wirzba, A. (2018). Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY. Physics Letters B, 784, 378-384
Open this publication in new window or tab >>Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 784, p. 378-384Article in journal (Refereed) Published
Abstract [en]

We report on the search for the rare decay eta -> pi(0)e(+)e(-) which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 x 10(7) events of the reaction pd -> He-3 eta have been recorded at an excess energy of Q = 59.8MeV. Based on this data set the C parity violating decay eta -> pi(0)gamma* -> pi(0)e(+)e(-) via a single-photon intermediate state has been searched for, resulting in new upper limits of Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> pi(+) pi(-) pi(0)) < 3.28 x 10(-5) and Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> all)< 7.5 x 10(-6) (CL=90%), respectively. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-368116 (URN)10.1016/j.physletb.2018.07.017 (DOI)000445781600056 ()
Funder
EU, FP7, Seventh Framework Programme, 227431Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06Bibliographically approved
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