Next-generation experiments searching for rare events must satisfy increasingly stringent requirements on the bulk and surface radioactive contamination of their active and structural materials. The ...measurement of surface contamination is particularly challenging, as no existing technology is capable of separately measuring parts of the 232Th and 238U decay chains that are commonly found to be out of secular equilibrium. We will present the results obtained with a detector prototype consisting of 8 silicon wafers of 150 mm diameter instrumented as bolometers and operated in a low-background dilution refrigerator at the Gran Sasso Underground Laboratory of INFN, Italy. The prototype was characterized by a baseline energy resolution of few keV and a background <100 nBq/cm2 in the full range of α energies, obtained with simple procedures for cleaning of all employed materials and no specific measures to prevent recontamination. Such performance, together with the modularity of the detector design, demonstrate the possibility to realize an alpha detector capable of separately measuring all alpha emitters of the 232Th and 238U chains, possibly reaching a sensitivity of few nBq/cm2.
•Material screening.•Bolometric alpha detector.•Low-radioactivity measurements.
Abstract
An array of twelve 0.28 kg lithium molybdate (LMO)
low-temperature bolometers equipped with 16 bolometric Ge light
detectors, aiming at optimization of detector structure for CROSS
and CUPID ...double-beta decay experiments, was constructed and tested
in a low-background pulse-tube-based cryostat at the Canfranc
underground laboratory in Spain. Performance of the scintillating
bolometers was studied depending on the size of phonon NTD-Ge
sensors glued to both LMO and Ge absorbers, shape of the Ge light
detectors (circular vs. square, from two suppliers), in different
light collection conditions (with and without reflector, with
aluminum coated LMO crystal surface). The scintillating bolometer
array was operated over 8 months in the low-background conditions
that allowed to probe a very low, μBq/kg, level of the LMO
crystals radioactive contamination by
228
Th and
226
Ra.
Abstract
CUPID is a next-generation bolometric experiment aiming at
searching for neutrinoless double-beta decay with ∼250 kg of
isotopic mass of
100
Mo. It will operate at ∼10 mK in a
cryostat ...currently hosting a similar-scale bolometric array for the
CUORE experiment at the Gran Sasso National Laboratory
(Italy). CUPID will be based on large-volume scintillating
bolometers consisting of
100
Mo-enriched Li
2
MoO
4
crystals,
facing thin Ge-wafer-based bolometric light detectors. In the CUPID
design, the detector structure is novel and needs to be
validated. In particular, the CUORE cryostat presents a high level
of mechanical vibrations due to the use of pulse tubes and the
effect of vibrations on the detector performance must be
investigated. In this paper we report the first test of the
CUPID-design bolometric light detectors with NTD-Ge sensors in a
dilution refrigerator equipped with a pulse tube in an above-ground
lab. Light detectors are characterized in terms of sensitivity,
energy resolution, pulse time constants, and noise power
spectrum. Despite the challenging noisy environment due to
pulse-tube-induced vibrations, we demonstrate that all the four
tested light detectors comply with the CUPID goal in terms of
intrinsic energy resolution of 100 eV RMS baseline noise. Indeed,
we have measured 70–90 eV RMS for the four devices, which show an
excellent reproducibility. We have also obtained high energy
resolutions at the 356 keV line from a
133
Ba source, as good
as Ge semiconductor
γ
detectors in this energy range.
An array of twelve 0.28 kg lithium molybdate (LMO)low-temperature bolometers equipped with 16 bolometric Ge lightdetectors, aiming at optimization of detector structure for CROSSand CUPID double-beta ...decay experiments, was constructed and testedin a low-background pulse-tube-based cryostat at the Canfrancunderground laboratory in Spain. Performance of the scintillatingbolometers was studied depending on the size of phonon NTD-Gesensors glued to both LMO and Ge absorbers, shape of the Ge lightdetectors (circular vs. square, from two suppliers), in differentlight collection conditions (with and without reflector, withaluminum coated LMO crystal surface). The scintillating bolometerarray was operated over 8 months in the low-background conditionsthat allowed to probe a very low, μBq/kg, level of the LMOcrystals radioactive contamination by 228Th and 226Ra.
CUPID is a next-generation bolometric experiment aiming at searching for neutrinoless double-beta decay with ~250 kg of isotopic mass of 100Mo. It will operate at ~10 mK in a cryostat currently ...hosting a similar-scale bolometric array for the CUORE experiment at the Gran Sasso National Laboratory (Italy). CUPID will be based on large-volume scintillating bolometers consisting of 100Mo-enriched Li2MoO4 crystals, facing thin Ge-wafer-based bolometric light detectors. In the CUPID design, the detector structure is novel and needs to be validated. In particular, the CUORE cryostat presents a high level of mechanical vibrations due to the use of pulse tubes and the effect of vibrations on the detector performance must be investigated. In this paper we report the first test of the CUPID-design bolometric light detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse tube in an above-ground lab. Light detectors are characterized in terms of sensitivity, energy resolution, pulse time constants, and noise power spectrum. Despite the challenging noisy environment due to pulse-tube-induced vibrations, we demonstrate that all the four tested light detectors comply with the CUPID goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise. Indeed, we have measured 70–90 eV RMS for the four devices, which show an excellent reproducibility. We have also obtained high energy resolutions at the 356 keV line from a 133Ba source, as good as Ge semiconductor γ detectors in this energy range.
An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers equipped with 16 bolometric Ge light detectors, aiming at optimization of detector structure for CROSS and CUPID ...double-beta decay experiments, was constructed and tested in a low-background pulse-tube-based cryostat at the Canfranc underground laboratory in Spain. Performance of the scintillating bolometers was studied depending on the size of phonon NTD-Ge sensors glued to both LMO and Ge absorbers, shape of the Ge light detectors (circular vs. square, from two suppliers), in different light collection conditions (with and without reflector, with aluminum coated LMO crystal surface). The scintillating bolometer array was operated over 8 months in the low-background conditions that allowed to probe a very low, μBq/kg, level of the LMO crystals radioactive contamination by 228Th and 226Ra.
Objective Human recombinant erythropoietin has been used to obtain a rapid increase in red blood cells before surgery. Previously, the shortest preparatory interval has been 4 days, but at the ...European Hospital only 2.4 days on average separate hospitalization and surgery. We therefore proposed a randomized blind trial to test the efficacy of high-dose erythropoietin for very short-term administration. Methods All patients presenting with a diagnosis of isolated coronary vessel disease were randomized to either erythropoietin therapy or a control group. Patients with a creatinine level greater than 2 mg/dL or hemoglobin level greater than 14.5 g/dL were excluded. Hemoglobin values were collected preoperatively and on postoperative days 1 and 4. Blood loss and blood transfusion rate were recorded at the time of discharge. Results We enrolled 320 consecutive patients in the study. No significant difference was found in preoperative parameters, postoperative blood loss, or mean preoperative hemoglobin levels. On postoperative day 4, mean hemoglobin was 15.5% higher in the erythropoietin group (10.70 ± 0.72 g/dL vs 9.26 ± 0.71 g/dL; P < .05). This group required 0.33 units of blood per patient, whereas the controls required 0.76 units per patient (risk ratio 0.43, P = .008). Conclusion A significant reduction in transfusion rate and a significant increase in hemoglobin values were observed in the erythropoietin group. No adverse events related to erythropoietin administration were recorded. A very short preoperative erythropoietin administration seems to be a safe and easy method to reduce the need for blood transfusions.
Objective Our objective was to evaluate the long-term survival and quality of life of patients who faced a prolonged (>10 days) postoperative stay in the intensive care unit and were discharged from ...the hospital. Methods Among 3125 consecutive patients who underwent cardiac operations in a 5-year period, we prospectively identified 57 who faced a prolonged postoperative intensive care unit stay and were discharged alive from the hospital. Patients were enrolled in a prospective follow-up protocol and evaluated every 6 to 12 months both clinically and instrumentally. Results Mean intensive care unit stay was 34 ± 9 days (range 11–141 days). Follow-up was complete and mean follow-up time was 71 months. Overall survival was 12 (21%) of 57, and the majority of follow-up deaths were cardiac related. Of the surviving patients, only a small minority (4/12) regained full autonomy and returned to their previous lifestyle. Risk factors for prolonged intensive care unit stay were age, New York Heart Association/Canadian Cardiovascular Society class, hypertension, diabetes, low ejection fraction, aortic surgery, preoperative renal failure, nonelective surgery, prolonged cardiopulmonary bypass time, and perioperative use of aortic counterpulsator. Conclusions Patients who face a prolonged postoperative intensive care unit stay and who were discharged from the hospital have a very poor long-term outcome and even worse quality of life. These data lead to a consideration of the wisdom of using heroic treatment in patients who face a prolonged postoperative intensive care unit stay in view of the dismal clinical results and enormous use of hospital and human resources.
Itinéraire méthodologique d'un anthropologue : la réflexivité, un choix théorico-méthodologkjue ou comment dépasser le récit de la présentation.
Claudia M. Girola 87-98.
En exposant un fragment de ...son itinéraire méthodologique dans l'étude des stratégies identitaires des personnes sans-abri, l'auteur a voulu signaler l'importance du travail de terrain (d'un point de vue d'une anthropologie réflexive) comme l'instance même de la production de la connaissance de la réalité sociale qu'on se propose de comprendre. Dans la rencontre entre chercheur et acteurs de la recherche considérée comme un processus d'interconnaissance active émerge la multiplicité de leurs appartenances réciproques. C'est là toute la richesse de cette démarche réflexive, surtout losqu'on travaille avec des personnes en situation de précarité extrême et de stigmatisation permanente. Ce processus analytique contribue à briser les images et les représentations réductrices dont sont «victimes» ces «hommes seuls, sans lien ni lieu» en permettant la reconnaissance de la complexité de leurs appartenances individuelles dans un monde social.
Anthropologisf s methodological itinerary : reflexivity, a theoretico-methodological choice or how to go beyond the story of the presentation.
Claudia M. Girola 87-98.
Through a presentation of a fragment of her methodological itinerary in the study of homeless people's identity strategies, the author underlines the importance of field-work as the matrix for understanding the social reality being observed. The multiplicity of identities, both of the researcher and of the agents of the study emerge from their encounter ; which is viewed as a process of mutual understanding and self-knowledge. Here in lies the fertility of this reflexive approach especially when working with people experiencing extreme pauverty and continual stigmatization. For such an analysis undermines reducing representations of these «solitary and rootless figures», thus revealing the complexities of their biographical histories, in a social context.
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