| 1. |
- Aprile, E., et al.
(author)
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The XENON1T dark matter experiment
- 2017
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:12
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Journal article (peer-reviewed)abstract
- The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2t liquid xenon inventory, 2.0t constitute the active target of the dual-phase time projection chamber. The scintillation and ionization signals from particle interactions are detected with low-background photomultipliers. This article describes the XENON1T instrument and its subsystems as well as strategies to achieve an unprecedented low background level. First results on the detector response and the performance of the subsystems are also presented.
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| 2. |
- Aprile, E., et al.
(author)
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First Dark Matter Search Results from the XENON1T Experiment
- 2017
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:18
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Journal article (peer-reviewed)abstract
- We report the first dark matter search results from XENON1T, a similar to 2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042 +/- 12)-kg fiducial mass and in the [5, 40] keV(nr) energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93 +/- 0.25) x 10(-4) events/(kg x day x keV(ee)), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10 GeV/c(2), with a minimum of 7.7 x 10(-47) cm(2) for 35-GeV/c(2) WIMPs at 90% C.L.
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| 3. |
- Aprile, E., et al.
(author)
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Online Rn-222 removal by cryogenic distillation in the XENON100 experiment
- 2017
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:6
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Journal article (peer-reviewed)abstract
- We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column was integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant Rn-222 background originating from radon emanation. After inserting an auxiliary 222Rn emanation source in the gas loop, we determined a radon reduction factor of R > 27 (95% C.L.) for the distillation column by monitoring the Rn-222 activity concentration inside the XENON100 detector.
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| 4. |
- Aprile, E., et al.
(author)
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Search for magnetic inelastic dark matter with XENON100
- 2017
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :10
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Journal article (peer-reviewed)abstract
- We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the DAMA/LIBRA collaboration with the null results from other direct detection experiments. No candidate event has been found in the region of interest and upper limits on the WIMP's magnetic dipole moment are derived. The scenarios proposed to explain the DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of WIMPs with masses of 58.0 GeV/c(2) and 122.7 GeV/c(2) are excluded at 3.3 sigma and 9.3 sigma, respectively.
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| 5. |
- Aprile, E., et al.
(author)
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Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon
- 2018
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In: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:9
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Journal article (peer-reviewed)abstract
- We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V/cm, 154 V/cm and 366 V/cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain Monte Carlo is used to extract the photon yields and recombination fluctuations from the experimental data. The photon yields measured at the two lower fields are in agreement with those from literature; additional measurements at a higher field of 366 V/cm are presented. The electronic and nuclear recoil discrimination as well as its dependence on the drift field and photon detection efficiency are investigated at these low energies. The results provide new measurements in the energy region of interest for dark matter searches using liquid xenon.
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| 6. |
- Aalbers, J., et al.
(author)
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DARWIN : towards the ultimate dark matter detector
- 2016
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :11
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Journal article (peer-reviewed)abstract
- DARk matter WImp search with liquid xenoN (DARWIN(2)) will be an experiment for the direct detection of dark matter using a multi-ton liquid xenon time projection chamber at its core. Its primary goal will be to explore the experimentally accessible parameter space for Weakly Interacting Massive Particles (WIMPs) in a wide mass-range, until neutrino interactions with the target become an irreducible background. The prompt scintillation light and the charge signals induced by particle interactions in the xenon will be observed by VUV sensitive, ultra-low background photosensors. Besides its excellent sensitivity to WIMPs above a mass of 5 GeV/c(2), such a detector with its large mass, low-energy threshold and ultra-low background level will also be sensitive to other rare interactions. It will search for solar axions,galactic axion-like particles and the neutrinoless double-beta decay of Xe-136, as well as measure the low-energy solar neutrino flux with <1% precision, observe coherent neutrino-nucleus interactions, and detect galactic supernovae. We present the concept of the DARWIN detector and discuss its physics reach, the main sources of backgrounds and the ongoing detector design and R&D efforts.
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| 7. |
- Aprile, E., et al.
(author)
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Low-mass dark matter search using ionization signals in XENON100
- 2016
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In: Physical Review D. - 2470-0010. ; 94:9
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Journal article (peer-reviewed)abstract
- We perform a low-mass dark matter search using an exposure of 30 kg x yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy threshold for detection to 0.7 keV for nuclear recoils. No dark matter detection can be claimed because a complete background model cannot be constructed without a primary scintillation signal. Instead, we compute an upper limit on the WIMP-nucleon scattering cross section under the assumption that every event passing our selection criteria could be a signal event. Using an energy interval from 0.7 keV to 9.1 keV, we derive a limit on the spin-independent WIMP-nucleon cross section that excludes WIMPs with a mass of 6 GeV/c(2) above 1.4 x 10(-41) cm(2) at 90% confidence level.
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| 8. |
- Aprile, E., et al.
(author)
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Physics reach of the XENON1T dark matter experiment
- 2016
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
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Journal article (peer-reviewed)abstract
- The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in 1 tonne fiducial volume and (1, 12) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80+/-0.15) . 10(-4) (kg.day.keV)(-1), mainly due to the decay of Rn-222 daughters inside the xenon target. The nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) keV, is composed of (0.6 +/- 0.1) (t.y)(-1) from radiogenic neutrons, (1.8+/-0.3) . 10(-2) (t.y)(-1) from coherent scattering of neutrinos, and less than 0.01 (t.y)(-1) from muon-induced neutrons. The sensitivity of XENON1T is calculated with the Pro file Likelihood Ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. We take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. The main contribution comes from the relative scintillation efficiency L-eff, which affects both the signal from WIMPs and the nuclear recoil backgrounds. After a 2 y measurement in 1 tonne fiducial volume, the sensitivity reaches a minimum cross section of 1.6 . 10(-47) cm(2) at m(chi) = 50 GeV/c(2).
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| 9. |
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| 10. |
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| 11. |
- von Sivers, M, et al.
(author)
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A techno-economical comparison of three processes for the production of ethanol from pine
- 1995
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In: Bioresource Technology. - 1873-2976. ; 51:1, s. 43-52
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Journal article (peer-reviewed)abstract
- This study comprises a technical and economic comparison of three different processes for the production of fuel ethanol from pine. The processes were based on the same technical and economic assumptions. The main difference between the processes lies in the front end of each process, i.e. in the pretreatment of the raw material and in the hydrolysis of the hemicellulose and cellulose to sugars. The three processes compared are a concentrated hydrochloric acid process, a two-step dilute acid process with sulphur dioxide in the first and hydrochloric acid in the second hydrolysis step, and an enzymatic hydrolysis process, including steam pretreatment. The ethanol production costs found in this study are, excluding the capital costs, 2.43, 1.89 and 1.80 SEK/l, respectively, and including the capital costs 4.22, 4.29 and 4.03 SEK/l, respectively. Based on a sensitivity analysis, it was concluded that none of the processes can be eliminated as less economical than the others.
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| 12. |
- von Sivers, M, et al.
(author)
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Cost Analysis of Ethanol Production from Willow Using Recombinant Escherichia coli
- 1994
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In: Biotechnology Progress. - : Wiley. - 1520-6033 .- 8756-7938. ; 10:5, s. 555-560
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Journal article (peer-reviewed)abstract
- This study comprises a technical and economic analysis of the production of fuel ethanol by fermentation of a pentose-rich hydrolysate with recombinant Escherichia coli, strain KO11. Hydrolysate from steam-pretreated willow was used as raw material in calculations regarding the fermentation. The calculations were based on a feed capacity of 10 metric tons of dry willow per hour to the pretreatment stage, providing 35 metric tons of hydrolysate per hour, consisting of 45 g of sugars/L, to the pentose fermentation plant. A detoxification step was included, since the hydrolysate has been shown to have an inhibitory effect on the E. coli KO11. The technical data used in the calculations were based on a kinetic fermentation model, which was developed from laboratory-scale experiments in a previous study. The economic analysis predicted an ethanol production cast of 48 cent/L in the pentose fermentation plant, indicating potentially good economy. The detoxification cost constitutes 22% of this cost. Sensitivity analyses revealed that if the concentration of sugars in the feed to the fermentation was decreased by 40% to 27 g/L, the ethanol production cost was increased to 54 cent/L. The production cost was increased to 50 cent/L ethanol if the cell mass was recirculated to the fermentation stage 5 times instead of 20.
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| 13. |
- von Sivers, M, et al.
(author)
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Ethanol from lignocellulosics: A review of the economy
- 1996
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In: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 56:2-3, s. 131-140
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Journal article (peer-reviewed)abstract
- The present study is a review of published investigations regarding the economy of ethanol production from lignocellulosic material The objective is to present relations between and tendencies observed in different cost estimates. The influence of plant capacity and overall product yield on the ethanol production cost is investigated, as well as variations in capital costs in the different processes. The underlying technical and economic assumptions show a large variation between the various studies published. The variation in the ethanol production cost is large, from 18 to 151 US cent/l. The most important factor for the economic outcome is the overall ethanol yield. Other important parameters are the feedstock cost, which was found to vary between 22 and 61 US$/dry metric ton, and the plant capacity, which influences the capital cost. It is shown that there is a tendency towards a decrease in ethanol production cost with an increase in plant capacity for the enzymatic processes. A high yield also results in a decrease in production cost for the enzymatic and dilute acid processes in the papers reviewed. Copyright (C) 1996 Elsevier Science Ltd.
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