| 1. |
- Blumer, P., et al.
(författare)
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Positron accumulation in the GBAR experiment
- 2022
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1040
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Tidskriftsartikel (refereegranskat)abstract
- We present a description of the GBAR positron (e+) trapping apparatus, which consists of a three stage Buffer Gas Trap (BGT) followed by a High Field Penning Trap (HFT), and discuss its performance. The overall goal of the GBAR experiment is to measure the acceleration of the neutral antihydrogen (H¯) atom in the terrestrial gravitational field by neutralising a positive antihydrogen ion (H¯+), which has been cooled to a low temperature, and observing the subsequent H¯ annihilation following free fall. To produce one H¯+ ion, about 1010 positrons, efficiently converted into positronium (Ps), together with about 107 antiprotons (p¯), are required. The positrons, produced from an electron linac-based system, are accumulated first in the BGT whereafter they are stacked in the ultra-high vacuum HFT, where we have been able to trap 1.4(2) × 109 positrons in 1100 s.
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| 2. |
- Charlton, M., et al.
(författare)
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Positron production using a 9 MeV electron linac for the GBAR experiment
- 2021
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 985
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Tidskriftsartikel (refereegranskat)abstract
- For the GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment at CERN's Antiproton Decelerator (AD) facility we have constructed a source of slow positrons, which uses a low-energy electron linear accelerator (linac). The driver linac produces electrons of 9 MeV kinetic energy that create positrons from bremsstrahlung-induced pair production. Staying below 10 MeV ensures no persistent radioactive activation in the target zone and that the radiation level outside the biological shield is safe for public access. An annealed tungsten-mesh assembly placed directly behind the target acts as a positron moderator. The system produces 5 x 10(7) slow positrons per second, a performance demonstrating that a low-energy electron linac is a superior choice over positron-emitting radioactive sources for high positron flux.
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| 3. |
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| 4. |
- Husson, A., et al.
(författare)
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A pulsed high-voltage decelerator system to deliver low-energy antiprotons
- 2021
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1002
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Tidskriftsartikel (refereegranskat)abstract
- The GBAR (Gravitational Behavior of Antihydrogen at Rest) experiment at CERN requires efficient deceleration of 100 keV antiprotons provided by the new ELENA synchrotron ring to synthesize antihydrogen. This is accomplished using electrostatic deceleration optics and a drift tube that is designed to switch from -99 kV to ground when the antiproton bunch is inside – essentially a charged particle “elevator” – producing a 1 keV pulse. We describe the simulation, design, construction and successful testing of the decelerator device at -92 kV on-line with antiprotons from ELENA.
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| 5. |
- Kim, B. H., et al.
(författare)
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Development of a PbWO4 Detector for Single-Shot Positron Annihilation Lifetime Spectroscopy at the GBAR Experiment
- 2020
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Ingår i: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 137:2, s. 122-125
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a PbWO4 (PWO) detector with a large dynamic range to measure the intensity of a positron beam and the absolute density of the ortho-positronium (o-Ps) cloud it creates. A simulation study shows that a setup based on such detectors may be used to determine the angular distribution of the emission and reflection of o-Ps to reduce part of the uncertainties of the measurement. These will allow to improve the precision in the measurement of the cross-section for the (anti)hydrogen formation by (anti)proton-positronium charge exchange and to optimize the yield of antihydrogen ion which is an essential parameter in the GBAR experiment.
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| 6. |
- Niang, S., et al.
(författare)
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Accumulation of Positrons from a LINAC Based Source
- 2020
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Ingår i: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 137:2, s. 164-166
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Tidskriftsartikel (refereegranskat)abstract
- The GBAR experiment aims to measure the gravitational acceleration of antihydrogen (H) over bar. It will use (H) over bar (+) ions formed by the interaction of antiprotons with a dense positronium cloud, which will require about 1010 positrons to produce one (H) over bar (+). We present the first results on the positron accumulation, reaching 3.8 +/- 0.4x10(8) e(+) collected in 560 s.
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| 11. |
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| 12. |
- Feugnet, G., et al.
(författare)
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Improved laser-induced fluorescence method for bio-attack early warning detection system
- 2008
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- Laser Induced Fluorescence (LIF) could permit fast early warning systems either for point or standoff detection if a reliable classification of warfare biological agents versus biological or non-biological fluorescing background can be achieved. In order to improve LIF discrimination capability, a new system is described in which the fluorescence pattern is enriched by the use of multiple wavelength delayed excitation while usual spectral fluorescence analysis is extended to time domain to use both aspects as criteria for classification. General considerations and guidelines for the system design are given as well as results showing good discrimination between background and simulants.
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| 13. |
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| 17. |
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| 18. |
- La Rosee, P, et al.
(författare)
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Recommendations for the management of hemophagocytic lymphohistiocytosis in adults
- 2019
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 133:23, s. 2465-2477
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Tidskriftsartikel (refereegranskat)abstract
- Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory syndrome induced by aberrantly activated macrophages and cytotoxic T cells. The primary (genetic) form, caused by mutations affecting lymphocyte cytotoxicity and immune regulation, is most common in children, whereas the secondary (acquired) form is most frequent in adults. Secondary HLH is commonly triggered by infections or malignancies but may also be induced by autoinflammatory/autoimmune disorders, in which case it is called macrophage activation syndrome (MAS; or MAS-HLH). Most information on the diagnosis and treatment of HLH comes from the pediatric literature. Although helpful in some adult cases, this raises several challenges. For example, the HLH-2004 diagnostic criteria developed for children are commonly applied but are not validated for adults. Another challenge in HLH diagnosis is that patients may present with a phenotype indistinguishable from sepsis or multiple organ dysfunction syndrome. Treatment algorithms targeting hyperinflammation are frequently based on pediatric protocols, such as HLH-94 and HLH-2004, which may result in overtreatment and unnecessary toxicity in adults. Therefore, dose reductions, individualized tailoring of treatment duration, and an age-dependent modified diagnostic approach are to be considered. Here, we present expert opinions derived from an interdisciplinary working group on adult HLH, sponsored by the Histiocyte Society, to facilitate knowledge transfer between physicians caring for pediatric and adult patients with HLH, with the aim to improve the outcome for adult patients affected by HLH.
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| 19. |
- Milisavljevic, Dan, et al.
(författare)
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A JWST Survey of the Supernova Remnant Cassiopeia A
- 2024
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 965:2
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Tidskriftsartikel (refereegranskat)abstract
- We present initial results from a James Webb Space Telescope (JWST) survey of the youngest Galactic core-collapse supernova remnant, Cassiopeia A (Cas A), made up of NIRCam and MIRI imaging mosaics that map emission from the main shell, interior, and surrounding circumstellar/interstellar material (CSM/ISM). We also present four exploratory positions of MIRI Medium Resolution Spectrograph integral field unit spectroscopy that sample ejecta, CSM, and associated dust from representative shocked and unshocked regions. Surprising discoveries include (1) a weblike network of unshocked ejecta filaments resolved to ∼0.01 pc scales exhibiting an overall morphology consistent with turbulent mixing of cool, low-entropy matter from the progenitor's oxygen layer with hot, high-entropy matter heated by neutrino interactions and radioactivity; (2) a thick sheet of dust-dominated emission from shocked CSM seen in projection toward the remnant's interior pockmarked with small (∼1'') round holes formed by ≲01 knots of high-velocity ejecta that have pierced through the CSM and driven expanding tangential shocks; and (3) dozens of light echoes with angular sizes between ∼01 and 1' reflecting previously unseen fine-scale structure in the ISM. NIRCam observations place new upper limits on infrared emission (≲20 nJy at 3 μm) from the neutron star in Cas A's center and tightly constrain scenarios involving a possible fallback disk. These JWST survey data and initial findings help address unresolved questions about massive star explosions that have broad implications for the formation and evolution of stellar populations, the metal and dust enrichment of galaxies, and the origin of compact remnant objects.
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| 20. |
- Pepitone, Kevin, Dr, 1988-, et al.
(författare)
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Design of a Canted-Cosine-Theta Orbit Corrector for the High Luminosity LHC
- 2022
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Ingår i: IEEE transactions on applied superconductivity (Print). - : IEEE. - 1051-8223 .- 1558-2515. ; 32:6
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Tidskriftsartikel (refereegranskat)abstract
- The High Luminosity LHC requires dipole orbit correctors grouped in double aperture magnet assemblies. They provide a field of 3.1 T at 100 A in an aperture of 70 mm. The current standard design is a classical cosine-theta layout made with ribbon cable. However, the electric insulation of this cable is not radiation-resistant enough to withstand the radiation load expected in the coming years of LHC operation. A new design, based on a cable with polyimide insulator, that can replace the existing orbit correctors, is needed. The challenge is to design a magnet that fits directly into the existing positions and that can operate with the same busbars, passive quench protection, and power supplies. The new orbit corrector design meets high requirements on the field quality while keeping within the same mechanical volume and maximum excitation current. A collaboration of Swedish universities and Swedish industry has been formed for the development and production of a prototype magnet following a concurrent engineering methodology to reduce the time needed to produce a CCT magnet. The magnet has a 1 m long CCT dipole layout consisting of two coils. The superconductor is a commercially available 0.33 mm wire with polyimide insulation in a 6-around-1 cable. The channels in the coil formers, that determine the CCT layout, allow for 2 x 5 cable layers. A total of 70 windings makes that the coil current can be kept below 100 A. We will present the detailed design and preliminary quench simulations.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 25. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 26. |
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| 27. |
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| 28. |
- Bagni, T., et al.
(författare)
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Modeling Results of the Quench Behavior of a Nb-Ti Canted-Cosine-Theta Corrector Magnet for LHC
- 2024
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Ingår i: IEEE transactions on applied superconductivity (Print). - : IEEE. - 1051-8223 .- 1558-2515. ; 34:5
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Tidskriftsartikel (refereegranskat)abstract
- A newly designed superconducting magnet of the Canted-Cosine-Theta (CCT) type was developed as a result of a collaboration between Swedish universities (Uppsala and Linneaus) and Swedish industries. This magnet was designed to function as a replacement of the present LHC orbit corrector magnets, which are approaching their end of life due to the radiation load. As a result, the new CCT magnet was developed to be more radiation tolerant and to constitute a one-to-one replacement to the currently installed version, which is a 1 m long 70 mm double aperture dipole magnet. The final magnet, which is currently under construction, will be tested at FREIA laboratory at Uppsala University and generate a magnetic field of 3.3 T and an integrated field of 2.8 Tm at about 85 A. To examine the magnet quench behavior and to identify a suitable quench protection system, the 3D electro-magnetic and thermal behavior of the coil was modeled using the RAT-Raccoon software. Based on the simulation results, a Metrosil varistor was selected to protect the magnet during the test. In this article, we report the results of the numerical analysis. The magnet model is equipped with a spot heater to initialize the quench and the temperature and voltages are monitored during the avalanche effect. The simulated current decay and the hot-spot temperature are analyzed with a focus on the impact of quench-back on the magnet protection.
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| 29. |
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| 30. |
- Dickson, Nigel P., et al.
(författare)
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Male Circumcision and Serologically Determined Human Papillomavirus Infection in a Birth Cohort
- 2009
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Ingår i: Cancer Epidemiology Biomarkers & Prevention. - 1538-7755. ; 18:1, s. 177-183
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Tidskriftsartikel (refereegranskat)abstract
- Circumcision has been reported to protect against infection with human papillomavirus (HPV) in men, but results have been inconsistent. We followed males in a birth cohort born in Dunedin, New Zealand, in 1972 and 1973 from age 3 to 32 years. Seropositivity at age 32 years for the oncogenic types HPV-16 and 18, and the nononcogenic types 6 and 11, was studied in relation to maternal reports of circumcision status at age 3 for 450 men. Seropositivity to any of these types was associated with lifetime number of sexual partners (P = 0.03), and lower moral-religious emphasis of the family of origin (P < 0.001). Circumcision was not found to be protective, with the adjusted odds ratio (95% confidence interval) for HPV6/11/16/18 seropositivity among the circumcised compared with the uncircumcised being 1.4 (0.89-2.2).
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| 31. |
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| 37. |
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| 39. |
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| 42. |
- Keri, S, et al.
(författare)
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Patients with schizophreniform disorder use verbal descriptions for the representation of visual categories
- 2004
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Ingår i: Psychological medicine. - : Cambridge University Press (CUP). - 0033-2917 .- 1469-8978. ; 34:2, s. 247-253
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Tidskriftsartikel (refereegranskat)abstract
- Background. Neuropsychological impairment is a common finding in schizophrenia. However, a significant proportion of patients are not impaired in conventional neuropsychological tests. In this study, we investigated whether remitted patients with schizophreniform disorder exhibited dysfunctions in specific cognitive tasks.Method. Twenty remitted, highly functioning patients with schizophreniform disorder and 20 control subjects participated in the study. In addition to background neuropsychological evaluation (WAIS-R IQ, Wisconsin Card Sorting Test (WCST), Trail Making B, Rey–Osterrieth Complex Figure), subjects received a category learning task. The categories consisted of geometric shapes systematically changing in shape and size. Training included the sequential presentation of category members (visual learning) and verbal description of categories.Results. The patients with schizophreniform disorder had normal IQ, executive functions/psychomotor speed (WCST and Trail Making B) and visual memory (Rey–Osterrieth Complex Figure). In contrast, they displayed impaired categorization performances after visual learning. The performance of the patients improved markedly after verbal description of categories. Verbal knowledge about categories positively correlated with categorization performance in the patients, but not in the controls.Conclusions. Category learning functions, which include decision-making under uncertainty and feature integration, are impaired in patients with schizophreniform disorder who display normal executive functions and visual memory. These patients may use verbal knowledge as a compensatory strategy in visual tasks.
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| 43. |
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| 44. |
- Pepitone, K., et al.
(författare)
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Design and Fabrication of a Canted-Cosine-Theta Double Aperture Orbit Corrector Dipole for the LHC
- 2023
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Ingår i: IEEE transactions on applied superconductivity (Print). - : IEEE. - 1051-8223 .- 1558-2515 .- 2378-7074. ; 33:5
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Tidskriftsartikel (refereegranskat)abstract
- A prototype CCT dipole magnet developed by a collaboration between Swedish universities, Swedish industry and CERN will be tested at Uppsala University. This 1 m long double-aperture magnet can provide a field strength of 3.3 T at 85 A in a 70 mm aperture with an integrated field of 2.8 Tm. It is intended to replace the current LHC orbit corrector magnets which are reaching the end of their expected life due to the radiation load. The new magnet is designed to handle the radiation dose of the upgrade to the high-luminosity LHC, which will deliver about ten times the current radiation dose. It must therefore be more resistant to radiation and meet strict requirements in terms of electrical insulation while matching the original field quality and self-protective capability, mechanical volume, and maximum excitation current. This paper will present the latest of the design and manufacturing work, including the results of simulations of the mechanical field and the mechanical stress. Details of the various tests performed before machining the parts are also presented.
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| 45. |
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| 47. |
- Ryding, Janka, et al.
(författare)
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Seroepidemiology as basis for design of a human papillomavirus vaccination program.
- 2008
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Ingår i: Vaccine. - : Elsevier BV. - 1873-2518 .- 0264-410X. ; Aug 8, s. 5263-5268
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a serological survey of HPV type 16-antibody prevalence by age and sex in Sweden and used it as a basis for modelling the optimal vaccination strategies in this population. Samples of 3317 subjects were tested for HPV16-specific antibodies. The observed age-specific seroprevalences along with sexual behaviour data were used to infer parameter values for a mathematical model representing Sweden and the preventive effect of possible strategies estimated. By the year 2055, vaccination of females starting at age 12 in 2008 was most efficient, estimated to prevent 5.8 million cumulative HPV16 infections. Catch-up programs had a strong additional preventive effect. Vaccination also targeting males increased protective effect by about 4%, but had lower preventive effect per vaccination given. Addition of an HPV serosurvey to existing models and data has enabled us to estimate effect of different vaccination strategies, optimized to the HPV epidemiology in our population.
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