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- Abgrall, N., et al.
(författare)
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The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)
- 2017
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Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. ; 1894
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Konferensbidrag (refereegranskat)abstract
- The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.
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| 2. |
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| 3. |
- Farrell, J. P., et al.
(författare)
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Ultrafast X-ray probe of nucleobase photoprotection
- 2012
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Ingår i: Quantum Electronics and Laser Science Conference. - 9781467318396 ; , s. 6327153-
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Konferensbidrag (refereegranskat)abstract
- We will present first results of a UV-pump X-ray-probe study of the photoprotection mechanism of thymine. The experiment used element specific Auger spectroscopy and was carried out at the LCLS.
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| 4. |
- McFarland, B. K., et al.
(författare)
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Probing nucleobase photoprotection with soft x-rays
- 2013
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Ingår i: XVIIITH INTERNATIONAL CONFERENCE ON ULTRAFAST PHENOMENA. - : EDP Sciences. - 9782759809561 ; , s. 07004-
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Konferensbidrag (refereegranskat)abstract
- Nucleobases absorb strongly in the ultraviolet region, leading to molecular excitation into reactive states. The molecules avoid the photoreactions by funnelling the electronic energy into less reactive states on an ultrafast timescale via non-Born-Oppenheimer dynamics. Current theory on the nucleobase thymine discusses two conflicting pathways for the photoprotective dynamics. We present our first results of our free electron laser based UV-pump soft x-ray-probe study of the photoprotection mechanism of thymine. We use the high spatial sensitivity of the Auger electrons emitted after the soft x-ray pulse induced core ionization. Our transient spetra show two timescales on the order of 200 fs and 5 ps, in agreement with previous (all UV) ultrafast experiments. The timescales appear at different Auger kinetic energies which will help us to decipher the molecular dynamics.
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| 7. |
- Duane Loh, N., et al.
(författare)
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Profiling structured beams using injected aerosols
- 2012
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Ingår i: Proceedings of SPIE. - : SPIE. - 9780819492210 ; , s. 850403-
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Konferensbidrag (refereegranskat)abstract
- Profiling structured beams produced by X-ray free-electron lasers (FELs) is crucial to both maximizing signal intensity for weakly scattering targets and interpreting their scattering patterns. Earlier ablative imprint studies describe how to infer the X-ray beam profile from the damage that an attenuated beam inflicts on a substrate. However, the beams in-situ profile is not directly accessible with imprint studies because the damage profile could be different from the actual beam profile. On the other hand, although a Shack-Hartmann sensor is capable of in-situ profiling, its lenses may be quickly damaged at the intense focus of hard X-ray FEL beams. We describe a new approach that probes the in-situ morphology of the intense FEL focus. By studying the translations in diffraction patterns from an ensemble of randomly injected sub-micron latex spheres, we were able to determine the non-Gaussian nature of the intense FEL beam at the Linac Coherent Light Source (SLAC National Laboratory) near the FEL focus. We discuss an experimental application of such a beam-profiling technique, and the limitations we need to overcome before it can be widely applied.
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| 9. |
- Taguchi, Akira, et al.
(författare)
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Visual assessment of non-eroded thin cortex on panoramic radiographs in identifying women with osteoporosis : Osteoporosis Screening Project in Dentistry (OSPD)
- 2009
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Ingår i: Programme and abstract book. ; , s. 65-65
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction The presence of an eroded or thinned cortex of the mandible on panoramic radiographs may be useful in identifying women with osteoporosis. However, little is known as to whether a non-eroded thin cortex predicts osteoporosis. Objective To clarify whether visual assessment of non-eroded thin cortex increases the diagnostic efficacy of identifying women with osteoporosis. Materials and methods Of 60 observers who participated in OSPD (Taguchi et al., Bone, 2008), 41 observers visually assessed non-eroded thin cortex in addition to Klemetti’s index (KI) for 100 panoramic radiographs on the OSPD website via the Internet twice with approximately a two-week interval. The area under the receiver operating characteristics curves (AUROC) in identifying women with osteoporosis by both KI and non-eroded thin cortex was calculated on two occasions; non-eroded thin cortex was included in “class 1 of KI (decreased probability of osteoporosis)” or “class 3 of KI (increased probability of osteoporosis)”. Mean AUROC was compared between these two occasions with paired ttest. Results In the first series of observations, the mean AUROC significantly increased when noneroded thin cortex was considered as a sign of increased probability of osteoporosis (mean +/- SD, 0.68 +/- 0.08 vs. 0.70 +/- 0.07, P=0.011). In the second set of observations, the result was unchanged (0.68 +/- 0.09 vs. 0.71 +/- 0.08, P<0.001). Conclusions and discussion Visual identification of a non-eroded thin cortex on panoramic radiographs may increase the diagnostic efficacy of identifying women with osteoporosis.
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| 10. |
- Caleman, Carl, et al.
(författare)
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Modeling of XFEL induced ionization and atomic displacement in protein nanocrystals
- 2012
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Ingår i: Proceedings of SPIE. - : SPIE. - 9780819492210 ; , s. 85040H-
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Konferensbidrag (refereegranskat)abstract
- X-ray free-electron lasers enable high-resolution imaging of biological materials by using short enough pulses to outrun many of the effects of radiation damage. Experiments conducted at the LCLS have obtained diffraction data from single particles and protein nanocrystals at doses to the sample over 3 GGy. The details of the interaction of the X-ray FEL pulse with the sample determine the limits of this new paradigm for imaging. Recent studies suggest that in the case of crystalline samples, such as protein nanocrystals, the atomic displacements and loss of bound electrons in the crystal (due to the high X- ray intensity) has the effect of gating the diffraction signal, and hence making the experiment less radiation sensitive. Only the incident photon intensity in the first part of the pulse, before the Bragg diffraction has died out, is relevant to acquiring signal and the rest of the pulse will mainly contribute to a diffuse background. In this work we use a plasma based non-local thermodynamic equilibrium code to explore the displacement and the ionization of a protein nanocrystal at various X-ray wavelengths and intensities.
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