| 1. |
- Lestinsky, M., et al.
(author)
-
Physics book: CRYRING@ESR
- 2016
-
In: European Physical Journal: Special Topics. - : Springer Science and Business Media LLC. - 1951-6401 .- 1951-6355. ; 225:5, s. 797-882
-
Research review (peer-reviewed)abstract
- The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).
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| 2. |
- Öjekull, Jenny, 1973, et al.
(author)
-
Dissociative recombination of H+(H2O)3 and D+(D2O)3 water cluster ions with electrons: Cross sections and branching ratios
- 2007
-
In: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 127, s. 194301-194309
-
Journal article (peer-reviewed)abstract
- Dissociative recombination (DR) of the water cluster ions H+(H2O)3 and D+(D2O)3 with electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For the first time, absolute DR cross sections have been measured for H+(H2O)3 in the energy range of 0.001–0.8 eV, and relative cross sections have been measured for D+(D2O)3 in the energy range of 0.001–1.0 eV. The DR cross sections for H+(H2O)3 are larger than previously observed for H+(H2O)n (n=1,2), which is in agreement with the previously observed trend indicating that the DR rate coefficient increases with size of the water cluster ion. Branching ratios have been determined for the dominating product channels. Dissociative recombination of H+(H2O)3 mainly results in the formation of 3H2O+H (probability of 0.95±0.05) and with a possible minor channel resulting in 2H2O+OH+H2 (0.05±0.05). The dominating channels for DR of D+(D2O)3 are 3D2O+D (0.88±0.03) and 2D2O+OD+D2 (0.09±0.02). The branching ratios are comparable to earlier DR results for H+(H2O)2 and D+(D2O)2, which gave 2X2O+X (X=H,D) with a probability of over 0.9.
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| 3. |
- Lestinsky, M., et al.
(author)
-
CRYRING@ESR: present status and future research
- 2015
-
In: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 2015:T166
-
Conference paper (peer-reviewed)abstract
- The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s(-1), with a possibility for an upgrade to 7 T s(-1)), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in similar to 2017.
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| 4. |
- Någård, M. B., et al.
(author)
-
Dissociative recombination of D+(D2O)(2) water cluster ions with free electrons
- 2002
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 117:11, s. 5264-5270
-
Journal article (peer-reviewed)abstract
- Dissociative recombination (DR) of the water cluster ion D+(D2O)(2) has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). Cluster ions were injected into the ring and accelerated to an energy of 2.28 MeV. The stored ion beam was merged with an almost monoenergetic electron beam, and neutral fragments produced by DR were detected by an energy-sensitive surface barrier detector. The first experimental determinations of the absolute DR cross section and branching ratios for a cluster ion are reported. The cross section for the process D+(D2O)(2)+e(-) is large and reaches 6.10(-12) cm(2) at a low center-of-mass collision energy of 0.001 eV. The cross section has an E-1.19+/-0.02 dependence in the energy range 0.001-0.0052 eV, and a steeper slope with an E-1.70+/-0.12 dependence for E=0.052-0.324 eV. The general trends are similar to the results for previously studied molecular ions, but the cross section is higher in absolute numbers for the cluster ion. Thermal rate coefficients for electron temperatures of 50-2000 K are deduced from the cross section data and the rate coefficients are consequently also large. Branching ratios for the product channels are determined with a grid technique. Break-up into 2D(2)O+D is the dominating dissociation channel with a probability of 0.94+/-0.04. The channel resulting in the fragments D2O+OD+D-2 has a probability of 0.04+/-0.02, and the probability for formation of D3O+D2O is 0.02+/-0.03. The results are compared with data for molecular ions, and the cluster dissociation dynamics are discussed.
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| 5. |
- Strothkämper, Christian, et al.
(author)
-
Multilateral spectral radiance factor scalecomparison
- 2017
-
In: Applied Optics. - 1559-128X .- 2155-3165. ; 56:7, s. 1996-2006
-
Journal article (peer-reviewed)abstract
- The field of spectral radiance factor (SRF) measurements has seen growing interest in recent years. Scale conformity has so far only been established between the national metrology institutes (NMIs) of Germany and the USA. This study aims at a bigger, multilateral scale comparison. For this purpose, a total of six NMIs participated in a scale comparison of goniospectrophotometers based on neutral and colored diffusely reflecting ceramics samples. In addition, two universities, providing a home-built gonioreflectometer and two widely used commercially available color measurement instruments, respectively, were involved. The wavelength range of the scale comparison covers the visible wavelength range from 380 nm to 780 nm. Results indicate systematic issues and that the uncertainty evaluation of the NMIs requires further work; although for the greatest part of the covered spectral range the agreement is good.
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| 6. |
- Andersson, Pontus, 1971, et al.
(author)
-
Radiative lifetimes of metastable states of negative ions
- 2006
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622 .- 2469-9926 .- 2469-9934. ; 73, s. 032705-
-
Journal article (peer-reviewed)abstract
- We present a technique for measuring the radiative lifetimes of metastable states of negative ions that involves the use of a heavy-ion storage ring. The method has been applied to investigate the radiative decay of the np(3) P-2(1/2) levels of Te-(n=5) and Se-(n=4) and the 3p(3) D-2 state of Si- for which the J=3/2 and 5/2 levels were unresolved. All of these states are metastable and decay primarily by emission of E2 and M1 radiation. Multi Configuration Dirac-Hartree-Fock calculations of rates for the transitions in Te- and Se- yielded lifetimes of 0.45 s and 4.7 s, respectively. The measured values agree well with these predicted values. In the case of the D-2 state of Si-, however, our measurement was only able to set a lower limit on the lifetime. The upper limit of the lifetime that can be measured with our apparatus is set by how long the ions can be stored in the ring, a limit determined by the rate of collisional detachment. Our lower limit of 1 min for the lifetime of the D-2 state is consistent with both the calculated lifetimes of 162 s for the D-2(3/2) level and 27.3 h for the D-2(5/2) level reported by O'Malley and Beck and 14.5 h and 12.5 h, respectively, from our Breit-Pauli calculations.
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| 7. |
- Chartkunchand, K. C., et al.
(author)
-
Lifetimes of bound excited states of Pt-
- 2017
-
In: Journal of Physics: Conference Series, Vol. 875, no. 022051. - : IOP Publishing. - 1742-6588.
-
Conference paper (peer-reviewed)abstract
- Measurements of the radiative lifetimes of the two excited states of the platinum anion Pt- are presented. Pt- ions stored in the cryogenic ion storage ring DESIREE were photodetached at different photon wavelengths and the resulting yield of neutral Pt measured as a function of time was recorded. Analysis of the neutral decay curves show a 2.54 +/- 0.10 s lifetime for the higher-lying 5d(10)6(s) S-2(1/2) excited state and a lifetime in the range of 50-200 ms for the lower- lying 5d(9)6(s)(2) D-2(3/2) excited state. This is the first study to report the lifetime of a bound anion excited state with an electron configuration different from that of the anion ground state.
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| 8. |
- Chartkunchand, Kiattichart C., et al.
(author)
-
Radiative lifetimes of the bound excited states of Pt-
- 2016
-
In: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 94:3
-
Journal article (peer-reviewed)abstract
- © 2016 American Physical Society.The intrinsic radiative lifetimes of the 5d106sS1/22 and 5d96s2 D3/22 bound excited states in the platinum anion Pt- have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying 5d106s S1/22 state was measured to be 2.54±0.10s, while only a lifetime in the range of 50-200 ms could be estimated for the 5d96s2 D3/22 fine-structure level. The storage lifetime of the Pt- ion beam was measured to be a little over 15 min at a ring temperature of 13K. The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.
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| 9. |
- Ellmann, A, et al.
(author)
-
Radiative lifetime of a bound excited state of Te-
- 2004
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:25, s. 253002-
-
Journal article (peer-reviewed)abstract
- We report on the first experimental study of the lifetime of a bound excited state of a negative ion. A new experimental technique was developed and used to measure the radiative lifetime of the 5p(5) P-2(1/2) level of Te-. The experiment was performed in a magnetic storage ring, where a laser beam was applied along one of the straight sections. In the experiment the population of the excited J=1/2 level was probed each time the Te- ions passed through the laser field. A decay curve was built up by sampling the population of the excited level of the Te- ions as a function of time after injection into the ring. A multiconfiguration Dirac-Hartree-Fock calculation was performed in conjunction with the experiment. The calculation yielded a radiative lifetime of 0.45 s, in excellent agreement with the measured value of 0.42(5) s.
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| 10. |
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| 11. |
- Gorda, O., et al.
(author)
-
Ion-optical design of CRYRING@ESR
- 2015
-
In: Physica Scripta. - 0031-8949 .- 1402-4896. ; T166
-
Journal article (peer-reviewed)abstract
- In 2012 the CRYRING storage ring was delivered from Stockholm to Darmstadt as a part of the Swedish in-kind contribution to the FAIR project. The ring lattice has been slightly changed for optimal injection and to provide additional space for experiment equipment. For the injection from the experimental storage ring (ESR), a new transfer line has been designed. The local injector line has been significantly modified compared to the previous one in Stockholm taking into account the geometry of the existing GSI building. In this paper we present the ion-optical properties of CRYRING@ESR after the described modifications. Single-turn injection from the ESR and multi-turn injection from the local injector are discussed. Ion-optical calculations of fast and slow extraction from CRYRING are also presented. The closed orbit correction scheme is considered taking into account the future arrangement of the beam position monitors and correction magnets. Based on the results of the calculations the requirements for the magnet alignment are finally discussed.
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| 12. |
- Lestinsky, M., et al.
(author)
-
CRYRING@ESR: present status and future research
- 2015
-
In: Physica Scripta. - 0031-8949 .- 1402-4896. ; T166
-
Journal article (peer-reviewed)abstract
- The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s(-1), with a possibility for an upgrade to 7 T s(-1)), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in similar to 2017.
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| 13. |
- Misra, Deepankar, et al.
(author)
-
Two-Center Double-Capture Interference in Fast He2++H2 Collisions
- 2009
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:15, s. 153201-
-
Journal article (peer-reviewed)abstract
- We report the first observation of Young-type interference effects in a two-electron transfer process. These effects change strongly as the projectile velocity changes in fast (1.2 and 2.0 MeV) He^{2+}-H_2 collisions as manifested in strong variations of the double-electron capture rates with the H_2 orientation. This is consistent with fully quantum mechanical calculations, which ignore sequential electron transfer, and a simple projectile de Broglie wave picture assuming that two-electron transfer probabilities are higher in collisions where the projectile passes close to either one of the H_2 nuclei.
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| 14. |
- Montaigne, Helen, et al.
(author)
-
Dissociative recombination of the thioformyl (HCS+) and carbonyl sulfide (OCS+) cations
- 2005
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 631:1, s. 653-659
-
Journal article (peer-reviewed)abstract
- Branching ratios and absolute cross sections have been measured for the dissociative recombination of HCS+ and OCS+ at the CRYRING ion storage ring. In the case of OCS+, the channel leading to CO + S ( 83%) dominates, whereas the other exoergic pathways leading to CS + O (14%) and C + SO (3%) are of lesser importance. In the case of HCS+, fracture of the C - S bond is predominant (81%), with the production of H + CS accounting for the remainder (19%). The cross section of the reaction could be fitted by the expressions sigma = 1.41 x 10(-15)E(eV)(-1.11) and 4.47 x 10(-16)E(eV) (-1.14) cm(2) for HCS+ and OCS+, respectively. The derived energy dependences of the thermal reaction rate coefficients can be fitted by k(T) 9.7 x 10(-7)(T/300)(-0.57) and 3.5 x 10(-7)(T/300)(-0.62) cm(3) s(-1) for HCS+ and OCS+, respectively. We use these data to perform model calculations on the HCS+/CS abundance ratio in dark clouds and find that the models using the UMIST and Ohio State University databases have even more difficulty in accounting for the large observed ratio.
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| 15. |
- Schef, P, et al.
(author)
-
Disentanglement of magnetic field mixing reveals the spontaneous M2 decay rate for a metastable level in Xe
- 2005
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:2, s. 020501-
-
Journal article (peer-reviewed)abstract
- We have investigated the radiative decay of the metastable level 5d(4)D(7/2) in Xe+. Theoretically we find the decay to be heavily dominated by an M2 transition and not by M1/E2 transitions. Lifetime measurements of 5d(4)D(7/2) in a storage ring are difficult since magnetic mixing of the metastable with a short-lived level quenches its population. Decay rates were determined at different magnetic field strengths (B) in order to allow a nonlinear extrapolation to B=0. The experimental lifetime of 2.4 +/- 0.8 s was in agreement with the calculated value, but much smaller than previously estimated.
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| 16. |
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| 17. |
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| 18. |
- Thomas, Richard D., et al.
(author)
-
The double electrostatic ion ring experiment : A unique cryogenic electrostatic storage ring for merged ion-beams studies
- 2011
-
In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82:6, s. 065112-
-
Journal article (peer-reviewed)abstract
- We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate rings and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.
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| 19. |
- Öjekull, Jenny, 1973, et al.
(author)
-
Dissociative recombination of ammonia clusters studied by storage ring experiments
- 2006
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 125:19, s. 194306-
-
Journal article (peer-reviewed)abstract
- Dissociative recombination of ammonia cluster ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for dissociative recombination of H+(NH3)(2), H+(NH3)(3), D+(ND3)(2), and D+(ND3)(3) in the collision energy range of 0.001-27 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 1000 K are calculated from the experimental data and compared with earlier results. The fragmentation patterns for the two ions H+(NH3)(2) and D+(ND3)(2) show no clear isotope effect. Dissociative recombination of X+(NX3)(2) (X=H or D) is dominated by the product channels 2NX(3)+X [0.95 +/- 0.02 for H+(NH3)(2) and 1.00 +/- 0.02 for D+(ND3)(2)]. Dissociative recombination of D+(ND3)(3) is dominated by the channels yielding three N-containing fragments (0.95 +/- 0.05).
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| 20. |
- Öjekull, Jenny, 1973, et al.
(author)
-
Dissociative recombination of NH4+ and ND4+ ions : Storage ring experiments and ab initio molecular dynamics
- 2004
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:16, s. 7391-7399
-
Journal article (peer-reviewed)abstract
- The dissociative recombination (DR) process of NH4+ and ND4+ molecular ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for DR of NH4+ and ND4+ in the collision energy range 0.001-1 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 2000 K are calculated from the experimental data. The absolute cross section for NH4+ agrees well with earlier work and is about a factor of 2 larger than the cross section for ND4+. The dissociative recombination of NH4+ is dominated by the product channels NH3+H (0.85+/-0.04) and NH2+2H (0.13+/-0.01), while the DR of ND4+ mainly results in ND3+D (0.94+/-0.03). Ab initio direct dynamics simulations, based on the assumption that the dissociation dynamics is governed by the neutral ground-state potential energy surface, suggest that the primary product formed in the DR process is NH3+H. The ejection of the H atom is direct and leaves the NH3 molecule highly vibrationally excited. A fraction of the excited ammonia molecules may subsequently undergo secondary fragmentation forming NH2+H. It is concluded that the model results are consistent with gross features of the experimental results, including the sensitivity of the branching ratio for the three-body channel NH2+2H to isotopic exchange.
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| 21. |
- Andersson, Patrik U, 1970, et al.
(author)
-
Formation of Highly Rovibrationally Excited Ammonia from Dissociative Recombination of NH4
- 2010
-
In: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 1:17, s. 2519-2523
-
Journal article (peer-reviewed)abstract
- The internal energy distribution of ammonia formed in the dissociative recombination (DR) of NH4+ with electrons has been studied by an imaging technique at the ion storage ring CRYRING. The DR process resulted in the formation of NH3 + H (0.90 ± 0.01), with minor contributions from channels producing NH2 + H2 (0.05 ± 0.01) and NH2 + 2H (0.04 ± 0.02). The formed NH3 molecules were highly internally excited, with a mean rovibrational energy of 3.3 ± 0.4 eV, which corresponds to 70% of the energy released in the neutralization process. The internal energy distribution was semiquantitatively reproduced by ab initio direct dynamics simulations, and the calculations suggested that the NH3 molecules are highly vibrationally excited while rotational excitation is limited. The high internal excitation and the translational energy of NH3 and H will influence their subsequent reactivity, an aspect that should be taken into account when developing detailed models of the interstellar medium and ammonia-containing plasmas.
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| 22. |
- Fu, Jinglin, et al.
(author)
-
Survey of bidirectional transmittance distribution function measurement facilities by multilateral scale comparisons
- 2024
-
In: Metrologia. - : Institute of Physics. - 0026-1394 .- 1681-7575. ; 61:3
-
Journal article (peer-reviewed)abstract
- In recent years, a growing demand for the capability of performing accurate measurements of the bidirectional transmittance distribution function (BTDF) has been observed in industry, research and development, and aerospace applications. However, there exists no calibration and measurement capabilities-entry for BTDF in the database of the Bureau International des Poids et Mesures and to date no BTDF comparison has been conducted between different national metrology institutes (NMIs) or designated institutes (DIs). As a first step to a possible future key comparison and to test the existing capabilities of determining this measurand, two interlaboratory comparisons were performed. In comparison one, five samples of three different types of optical transmissive diffusers were measured by five NMIs and one DI. By specific sample choice, the focus for this study lay more on orientation-dependent scatter properties. In comparison two, where one NMI, one DI, one university, and three industrial partners investigated their measurement capabilities, the dependence on the orientation was not assessed, but two additional samples of the same material and different thickness were measured. Results of the two comparisons are presented, giving a good overview of existing experimental solutions, and showing specific sample-related problems to be solved for improved future BTDF measurements.
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| 23. |
- Geppert, W.D., et al.
(author)
-
Dissociative recombination of protonated methanol
- 2006
-
In: Faraday discussions. - Cambridge : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 133, s. 177-190
-
Journal article (peer-reviewed)abstract
- The branching ratios of the different reaction pathways and the overall rate coefficients of the dissociative recombination reactions of CH3OH2+ and CD3OD2+ have been measured at the CRYRING storage ring located in Stockholm, Sweden. Analysis of the data yielded the result that formation of methanol or deuterated methanol accounted for only 3 and 6% of the total rate in CH3OH2+ and CD3OD2+, respectively. Dissociative recombination of both isotopomeres mainly involves fragmentation of the C - O bond, the major process being the three-body break-up forming CH3, OH and H (CD3, OD and D). The overall cross sections are best fitted by sigma = 1.2 +/- 0.1 x 10(-15) E-1.15 +/- 0.02 cm(2) and sigma = 9.6 +/- 0.9 x 10(-16) E-1.20 +/- 0.02 cm(2) for CH3OH2+ and CD3OD2+, respectively. From these values thermal reaction rate coefficients of k(T) = 8.9 +/- 0.9 x 10(-7) (T/300) (- 0.59 +/- 0.02) cm(3) s(-1) (CH3OH2+) and k( T) = 9.1 +/- 0.9 x 10(-7) (T/ 300) (- 0.63 +/- 0.02) cm(3) s(-1)(CD3OD2+) can be calculated. A non-negligible formation of interstellar methanol by the previously proposed mechanism via radiative association of CH3+ and H2O and subsequent dissociative recombination of the resulting CH3OH2+ ion to yield methanol and hydrogen atoms is therefore very unlikely.
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| 24. |
- Hartman, Henrik, et al.
(author)
-
First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
-
In: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
-
Journal article (peer-reviewed)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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| 25. |
- Höpe, Andreas, et al.
(author)
-
"Multidimensional reflectometry for industry" (xD-Reflect) an European research project
- 2014
-
In: Proceedings of SPIE - The International Society for Optical Engineering 2014. - : SPIE.
-
Conference paper (peer-reviewed)abstract
- The European Metrology Research Program (EMRP) is a metrology-focused program of coordinated Research and Development (RD) funded by the European Commission and participating countries within the European Association of National Metrology Institutes (EURAMET). It supports and ensures research collaboration between them by launching and managing different types of project calls. Within the EMRP Call 2012 "Metrology for Industry", the joint research project (JRP) entitled "Multidimensional Reflectometry for Industry" (xD-Reflect) was submitted by a consortium of 8 National Metrology Institutes (NMIs) and 2 universities and was subsequently funded. The general objective of xD-Reflect is to meet the demands from industry to describe the overall macroscopic appearance of modern surfaces by developing and improving methods for optical measurements which correlate with the visual sensation being evoked. In particular, the project deals with the "Goniochromatism", "Gloss" and "Fluorescence" properties of dedicated artifacts, which will be investigated in three main work packages (WP). Two additional transversal WP reinforce the structure: "Modelling and Data Analysis" with the objective to give an irreducible set of calibration schemes and handling methods and "Visual Perception", which will produce perception scales for the different visual attributes. Multidimensional reflectometry involves the enhancement of spectral and spatial resolution of reference gonioreflectometers for BRDF measurements using modern detectors, conoscopic optical designs, CCD cameras, line scan cameras, and modern light sources in order to describe new effects like sparkle and graininess/coarseness. More information and updated news concerning the project can be found on the xD-Reflect website http://www.xdreflect.eu/.
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| 26. |
- Kamińska, Magdalena, et al.
(author)
-
Lifetime of the bound excited level in Ni
- 2016
-
In: Physical Review A. - 1050-2947 .- 1094-1622. ; 93:1
-
Journal article (peer-reviewed)abstract
- The intrinsic lifetime of the upper level in the bound-bound 3d(9) 4s(2) D-2(3/2) -> 3d(9) 4s(2) D-2(5/2) radiative transition in Ni- was measured to be 15.1 +/- 0.4 s. The experiment was performed at cryogenic temperatures in one of the ion-beam storage rings of the Double ElectroStatic Ion Ring ExpEriment facility at Stockholm University. The storage lifetime of the Ni- ion beam was measured to be close to 5 min at a ring temperature of 13 K.
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| 27. |
- Kaminska, M, et al.
(author)
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Storing keV negative ions for hours: Lifetime measurements in new time domains
- 2015
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
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Conference paper (peer-reviewed)abstract
- We have used one of the cryogenic ion storage rings of DESIREE to measure the lifetime of the 2P o 1/2 level in the sulfur anion to be 503 ± 43 seconds. This is orders of magnitude longer than any previously measured lifetime in a negatively charged ion.
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| 28. |
- Kristiansson, Moa K., 1989-, et al.
(author)
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High-precision electron affinity of oxygen
- 2022
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Journal article (peer-reviewed)abstract
- Negative ions are important in many areas of science and technology, e.g., in interstellar chemistry, for accelerator-based radionuclide dating, and in anti-matter research. They are unique quantum systems where electron-correlation effects govern their properties. Atomic anions are loosely bound systems, which with very few exceptions lack optically allowed transitions. This limits prospects for high-resolution spectroscopy, and related negative-ion detection methods. Here, we present a method to measure negative ion binding energies with an order of magnitude higher precision than what has been possible before. By laser-manipulation of quantum-state populations, we are able to strongly reduce the background from photodetachment of excited states using a cryogenic electrostatic ion-beam storage ring where keV ion beams can circulate for up to hours. The method is applicable to negative ions in general and here we report an electron affinity of 1.461 112 972(87) eV for O-16. High-precision measurements are useful to find isotopic shifts and electron correlation. Here the authors measure electron affinity and hyperfine splitting of atomic oxygen with higher precision than previous studies.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Lekman, Magnus, et al.
(author)
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The genetic interacting landscape of 63 candidate genes in Major Depressive Disorder : an explorative study
- 2014
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In: BioData Mining. - : Springer Science and Business Media LLC. - 1756-0381. ; 7, s. 19-
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Journal article (peer-reviewed)abstract
- Background: Genetic contributions to major depressive disorder (MDD) are thought to result from multiple genes interacting with each other. Different procedures have been proposed to detect such interactions. Which approach is best for explaining the risk of developing disease is unclear. This study sought to elucidate the genetic interaction landscape in candidate genes for MDD by conducting a SNP-SNP interaction analysis using an exhaustive search through 3,704 SNP-markers in 1,732 cases and 1,783 controls provided from the GAIN MDD study. We used three different methods to detect interactions, two logistic regressions models (multiplicative and additive) and one data mining and machine learning (MDR) approach. Results: Although none of the interaction survived correction for multiple comparisons, the results provide important information for future genetic interaction studies in complex disorders. Among the 0.5% most significant observations, none had been reported previously for risk to MDD. Within this group of interactions, less than 0.03% would have been detectable based on main effect approach or an a priori algorithm. We evaluated correlations among the three different models and conclude that all three algorithms detected the same interactions to a low degree. Although the top interactions had a surprisingly large effect size for MDD (e. g. additive dominant model P-uncorrected = 9.10E-9 with attributable proportion (AP) value = 0.58 and multiplicative recessive model with P-uncorrected = 6.95E-5 with odds ratio (OR estimated from beta 3) value = 4.99) the area under the curve (AUC) estimates were low (< 0.54). Moreover, the population attributable fraction (PAF) estimates were also low (< 0.15). Conclusions: We conclude that the top interactions on their own did not explain much of the genetic variance of MDD. The different statistical interaction methods we used in the present study did not identify the same pairs of interacting markers. Genetic interaction studies may uncover previously unsuspected effects that could provide novel insights into MDD risk, but much larger sample sizes are needed before this strategy can be powerfully applied.
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| 33. |
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| 34. |
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| 35. |
- Schmidt, Henning, et al.
(author)
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Evidence of Wave-Particle Duality for Single Fast Hydrogen Atoms
- 2008
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:8, s. 083201-
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Journal article (peer-reviewed)abstract
- We report the direct observation of interference effects in a Young's double-slit experiment where the interfering waves are two spatially separated components of the de Broglie wave of single 1.3 MeV hydrogen atoms formed close to either target nucleus in H+ + H2 electron-transfer collisions. Quantum interference strongly influences the results even though the hydrogen atoms have a de Broglie wavelength, \lambda_dB, as small as 25 fm.
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| 36. |
- Schmidt, HT, et al.
(author)
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Recoil-ion momentum distributions for transfer ionization in fast proton-He collisions
- 2005
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - : American physical society. - 1050-2947 .- 1094-1622. ; 72:1
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Journal article (peer-reviewed)abstract
- We present high-luminosity experimental investigations of the transfer ionization (TI:p+He -> H-0+He2++e(-)) process in collisions between fast protons and neutral helium atoms in the earlier inaccessibly high-energy range 1.4-5.8 MeV. The protons were stored in the heavy-ion storage and cooler ring CRYRING, where they intersected a narrow supersonic helium gas jet. We discuss the longitudinal recoil-ion momentum distribution, as measured by means of cold-target recoil-ion momentum spectroscopy and find that this distribution splits into two completely separated peaks at the high end of our energy range. These separate contributions are discussed in terms of the earlier proposed Thomas TI (TTI) and kinematic TI mechansims. The cross section of the TTI process is found to follow a sigma proportional to v(-b) dependence with b=10.78 +/- 0.27 in accordance with the expected v(-11) asymptotic behavior. Further, we discuss the probability for shake-off accompanying electron transfer and the relation of this TI mechanism to photodouble ionization. Finally the influence of the initial-state electron velocity distribution on the TTI process is discussed.
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| 37. |
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| 38. |
- Tokman, M, et al.
(author)
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Towards a determination of QED effects in Cu-like Pb recombination resonances near threshold
- 2001
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In: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 406-409
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Journal article (peer-reviewed)abstract
- Dielectronic recombination of Pb53+ has been studied and a resonance is detected only similar to 10(-4) eV above the ground state. The possibility to determine the Pb53+ (4p(1/2)) - Ph53+ (4s(1/2)) energy splitting with a similar accuracy from the determination of the resonance position is discussed. Such a precision can only be achieved by calculations which treat quantum electrodynamics (QED) in a many-body environment at a level which can still not be reached. A fully relativistic many-body calculation of the splitting is described and the uncertainties are discussed.
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| 39. |
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