| 1. |
- Gatchell, Michael, et al.
(författare)
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Commissioning of the DESIREE storage rings - a new facility for cold ion-ion collisions
- 2014
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Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488:1
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Konferensbidrag (refereegranskat)abstract
- We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2(-), C-3(-), C-4(-) etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat-and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.
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| 2. |
- Hartman, Henrik, et al.
(författare)
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First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
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| 3. |
- Thomas, Richard D., et al.
(författare)
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DESIREE : Physics with cold stored ion beams
- 2015
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Ingår i: DR2013. - : EDP Sciences. ; 84, s. 01004-01004
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Konferensbidrag (refereegranskat)abstract
- Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).
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| 4. |
- Klinge, Björn, et al.
(författare)
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The patient undergoing implant therapy : Summary and consensus statements: The 4th EAO Consensus Conference 2015
- 2015
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Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 26:S11, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The assignment for this working group was to update the existing knowledge regarding factors considered being of special relevance for the patient undergoing implant therapy. This included areas where conflicting opinions exists since long or recently has been expressed, like the role of antibiotic prophylaxis in dental implant surgery and peri-implantitis. Also areas with growing interest and concern such as patient-reported outcome measures (PROMs) and health-economy was included in this review. Materials and methods: The literature in the respective areas of interest (antibiotic prophylaxis, peri-implantitis, patient-reported outcome measurements and health-economic aspects) was searched using different strategies for the different papers. Search strategies ranged from a complex systematic review to systematic-and narrative reviews, depending on subject and available literature. All collected material was critically reviewed. Four manuscripts were subsequently presented for group analysis and discussion and plenum discussions and concensus approval. The selected areas were considered to be of key importance and relevance for the patient undergoing implant therapy. Results: The results and conclusions of the review process are presented in the respective papers. The group's conclusions, identified knowledge gaps, directions for future research and concensus statements are presented in this article. The following reviews were available for group discussions and the foundation for subsequent plenary sessions: Lund B, Hultin M, Tranaeus S, Naimi-Akbar A, Klinge B. (2015) Perioperative antibiotics in conjunction with dental implant placement. A complex systematic review. Renvert S & Quirynen M. (2015) Risk indicators for peri-implantitis. A narrative review. De Bruyn H, Raes S, Matthys C, Cosyn J. (2015) The current use of patient centered/reported outcomes in implant dentistry. A systematic review. Beikler T & Flemmig T. F. (2015) Economic evaluation of implant-supported prostheses. A narrative review.
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| 5. |
- Zechmeister, Mathias, et al.
(författare)
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The planet search programme at the ESO CES and HARPS. IV. The search for Jupiter analogues around solar-like stars
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 552:A78
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Tidskriftsartikel (refereegranskat)abstract
- Context. In 1992 we began a precision radial velocity survey for planets around solar-like stars with the Coudé Echelle Spectrograph and the Long Camera (CES LC) at the 1.4 m telescope in La Silla (Chile) resulting in the discovery of the planet ι Hor b. We have continued the survey with the upgraded CES Very Long Camera (VLC) and the HARPS spectrographs, both at the 3.6 m telescope, until 2007. Aims: In this paper we present additional radial velocities for 31 stars of the original sample with higher precision. The observations cover a time span of up to 15 years and permit a search for Jupiter analogues. Methods: The survey was carried out with three different instruments/instrument configurations using the iodine absorption cell and the ThAr methods for wavelength calibration. We combine the data sets and perform a joint analysis for variability, trends, and periodicities. We compute Keplerian orbits for companions and detection limits in case of non-detections. Moreover, the HARPS radial velocities are analysed for correlations with activity indicators (CaII H&K and cross-correlation function shape). Results: We achieve a long-term RV precision of 15 m/s (CES+LC, 1992-1998), 9 m/s (CES+VLC, 1999-2006), and 2.8 m/s (HARPS, 2003-2009, including archive data), respectively. This enables us to confirm the known planetary signals in ι Hor and HR 506 as well as the three known planets around HR 3259. A steady RV trend for ɛ Ind A can be explained by a planetary companion and calls for direct imaging campaigns. On the other hand, we find previously reported trends to be smaller for β Hyi and not present for α Men. The candidate planet ɛ Eri b was not detected despite our better precision. Also the planet announced for HR 4523 cannot be confirmed. Long-term trends in several of our stars are compatible with known stellar companions. We provide a spectroscopic orbital solution for the binary HR 2400 and refined solutions for the planets around HR 506 and ι Hor. For some other stars the variations could be attributed to stellar activity, as e.g. the magnetic cycle in the case of HR 8323. Conclusions: The occurrence of two Jupiter-mass planets in our sample is in line with the estimate of 10% for the frequency of giant planets with periods smaller than 10 yr around solar-like stars. We have not detected a Jupiter analogue, while the detections limits for circular orbits indicate at 5 AU a sensitivity for minimum mass of at least 1MJup (2MJup) for 13% (61%) of the stars.
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