380 research outputs found
Rejection of randomly coinciding events in LiMoO scintillating bolometers using light detectors based on the Neganov-Luke effect
Random coincidences of nuclear events can be one of the main background
sources in low-temperature calorimetric experiments looking for neutrinoless
double-beta decay, especially in those searches based on scintillating
bolometers embedding the promising double-beta candidate Mo, because of
the relatively short half-life of the two-neutrino double-beta decay of this
nucleus. We show in this work that randomly coinciding events of the
two-neutrino double decay of Mo in enriched LiMoO
detectors can be effectively discriminated by pulse-shape analysis in the light
channel if the scintillating bolometer is provided with a Neganov-Luke light
detector, which can improve the signal-to-noise ratio by a large factor,
assumed here at the level of on the basis of preliminary
experimental results obtained with these devices. The achieved pile-up
rejection efficiency results in a very low contribution, of the order of counts/(keVkgy), to the background counting rate
in the region of interest for a large volume ( cm)
LiMoO detector. This background level is very encouraging in
view of a possible use of the LiMoO solution for a bolometric
tonne-scale next-generation experiment as that proposed in the CUPID project
Observations of the Sunyaev-Zel'dovich effect at high angular resolution towards the galaxy clusters A665, A2163 and CL0016+16
We report on the first observation of the Sunyaev-Zel'dovich effect with the
Diabolo experiment at the IRAM 30 metre telescope. A significant brightness
decrement is detected in the direction of three clusters (Abell 665, Abell 2163
and CL0016+16). With a 30 arcsecond beam and 3 arcminute beamthrow, this is the
highest angular resolution observation to date of the SZ effect.Comment: 23 pages, 8 figures, 6 tables, accepted to New Astronom
First results of the ROSEBUD Dark Matter experiment
Rare Objects SEarch with Bolometers UndergrounD) is an experiment which
attempts to detect low mass Weak Interacting Massive Particles (WIMPs) through
their elastic scattering off Al and O nuclei. It consists of three small
sapphire bolometers (of a total mass of 100 g) with NTD-Ge sensors in a
dilution refrigerator operating at 20 mK in the Canfranc Underground
Laboratory. We report in this paper the results of several runs (of about 10
days each) with successively improved energy thresholds, and the progressive
background reduction obtained by improvement of the radiopurity of the
components and subsequent modifications in the experimental assembly, including
the addition of old lead shields. Mid-term plans and perspectives of the
experiment are also presented.Comment: 14 pages, 8 figures, submitted to Astroparticle Physic
Background suppression in massive TeO bolometers with Neganov-Luke amplified light detectors
Bolometric detectors are excellent devices for the investigation of
neutrinoless double-beta decay (0). The observation of such
decay would demonstrate the violation of lepton number, and at the same time it
would necessarily imply that neutrinos have a Majorana character. The
sensitivity of cryogenic detectors based on TeO is strongly limited by the
alpha background in the region of interest for the 0 of
Te. It has been demonstrated that particle discrimination in TeO
bolometers is possible measuring the Cherenkov light produced by particle
interactions. However an event-by-event discrimination with NTD-based light
detectors has to be demonstrated. We will discuss the performance of a
highly-sensitive light detector exploiting the Neganov-Luke effect for signal
amplification. The detector, being operated with NTD-thermistor and coupled to
a 750 g TeO crystal, shows the ability for an event-by-event identification
of electron/gamma and alpha particles. The extremely low detector baseline
noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of
TeO-based 0 experiment to an unprecedented level
YAG:Nd crystals as possible detector to search for double beta and alpha decay of neodymium
Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma
rays and alpha particles, radioactive contamination were studied with neodymium
doped yttrium-aluminum garnet (YAG:Nd). Applicability of YAG:Nd scintillators
to search for double beta decay and alpha activity of natural neodymium
isotopes are discussed.Comment: 10 pages, 4 fig
Hyperparathyroïdie Primaire durant la Gtrossesse: Etude d’Un cas Chru de Strasbourg
Introduction: L’hyperparathyroïdie primaire est une anomalie des glandes parathyroïdes avec hypersécrétion de parathormone (PTH), le plus souvent secondaire à un adénome parathyroïdien. Cas clinique: Il s’agit d’une patiente de 30 ans, troisième geste, primipare qui ne présente pas d’antécédents médicochirurgicaux particuliers sauf une césarienne à 41 semaines d’aménorrhée (SA) + 4 jours sous anesthésie générale pour altération du rythme cardiaque fœtal suite à un déclenchement par prostaglandines pour rupture prolongée des membranes. La grossesse en cours a été spontanée, marquée par plusieurs épisodes de coliques néphrétiques gauches sur lithiases urinaires dès le début. La patiente a été hospitalisée à 18 semaines d’aménorrhée pour hyperalgie lors d’un de ces épisodes avec discrète dilatation pyélocalicielle gauche à 10mm, sans infection urinaire associée. Le contrôle de la douleur a nécessité l’usage de morphiniques. Les résultats biologiques étaient en faveur d’une hyperparathyroïdie primaire diagnostiquée en fin de deuxième trimestre de grossesse. Ces résultats biologiques ont été confirmés par l’imagérie (échographie et scanner cervical). A la suite de ce bilan, une parathyroidectomie partielle a été réalisée à 31 semaines d’aménorrhée et deux jours. La calcémie était légèrement supérieure à la normale à 2.60 mmol/L avec une PTH à 105 ng/L le jour de l’intervention. La lésion a été analysée en anatomopathologie et confirmait la nature d’adénome mesurant 10x8x2 mm. La calcémie corrigée a nettement diminué suite à la chirurgie. La vitalité fœtale évaluée avec le score de Manning et les cardiotocographies étaient satisfaisantes avant et après l’intervention chirurgicale. Le suivi immédiat en post chirurgie était simple : une supplémentation calcique pour environ 15 jours a été utilisée suite à une hypocalcémie secondaire. La chirurgie a permis une amélioration nette de la symptomatologie de notre patiente de façon quasi immédiate. Une césarienne sous rachianesthésie pour désir maternel en début de travail a été réalisée à 39 semaines d’aménorrhées et 6 jours, dans le contexte d’utérus cicatriciel, donnant naissance à une petite fille de 3490g et 50 cm, APGAR 10-10-10-10 avec un pH artériel au cordon à 7,28. Aucune complication materno-fœtale n’a été rapportée dans le post-partum. Un suivi endocrinologique a été proposé au post-partum ainsi qu’un suivi urologique. Discussion: Sur le plan épidémiologique, l’hyperparathyroïdie est la troisième endocrinopathie la plus fréquente dans la population générale. Les patientes atteintes ont une symptomatologie très aspécifique. Le calcium est essentiel au bon fonctionnement de l’homéostasie chez l’homme et la femme, tant sur les plans neurologique, musculaire, hémostatique, que sur les plans de la multiplication et différenciation cellulaire. Il est donc nécessaire qu’un système puisse réguler de manière constante le phosphore et le calcium dans l’organisme car les complications maternofoetales surviennent en l’absence de diagnostic précoce. Plusieurs options thérapeutiques peuvent été envisagées et proposées à la patiente allant d’un simple suivi de contrôle régulier de la calcémie à la parathyroidectomie sélective en passant par un traitement médicamenteux. Notre cas clinique illustre un traitement chirurgical efficace au troisième trimestre de grossesse. Conclusion: La parathyroidectomie pendant le 3e trimestre de grossesse est une thérapeutique efficace pour le traitement de l’hyperparathyroïdie primaire symptomatique.
Introduction: Primary hyperparathyroidism is an abnormality of the parathyroid glands with parathyroid hormone hypersecretion (PTH), most often secondary to parathyroid adenoma. Clinical case: This is a 30-year-old patient, third procedure, primiparous who has no specific medical and surgical history except a cesarean section at 41 weeks of amenorrhea (AS) + 4 days under general anesthesia for impaired fetal heart rate. triggering by prostaglandins for prolonged rupture of membranes. The current pregnancy was spontaneous, marked by several episodes of renal colic on the left on urolithiasis from the start. The patient was hospitalized at 18 weeks amenorrhea for hyperalgesia during one of these episodes with discreet left pyelocalicular dilation to 10mm, without associated urinary tract infection. Pain control required the use of opioids. The laboratory results were in favor of primary hyperparathyroidism diagnosed at the end of the second trimester of pregnancy. These laboratory results were confirmed by imaging (ultrasound and cervical scan). Following this workup, a partial parathyroidectomy was performed at 31 weeks of amenorrhea and two days. Serum calcium was slightly above normal at 2.60 mmol / L with PTH of 105 ng / L on the day of surgery. The lesion was analyzed for anatomopathology and confirmed the nature of the adenoma measuring 10x8x2 mm. The corrected serum calcium significantly decreased following the surgery. Fetal vitality assessed with Manning's score and cardiotocographies were satisfactory before and after surgery. Immediate post-surgery follow-up was simple: calcium supplementation for around 15 days was used following secondary hypocalcaemia. The surgery allowed a marked improvement in the symptoms of our patient almost immediately. A cesarean section under spinal anesthesia for maternal desire at the start of labor was performed at 39 weeks of amenorrhea and 6 days, in the context of a scarred uterus, giving birth to a baby girl of 3490g and 50 cm, APGAR 10-10-10 -10 with an arterial cord pH of 7.28. No maternal-fetal complications have been reported in the postpartum period. Endocrinological follow-up has been proposed postpartum as well as urological follow-up. Discussion: Epidemiologically, hyperparathyroidism is the third most common endocrinopathy in the general population. The affected patients have very nonspecific symptoms. Calcium is essential for the proper functioning of homeostasis in men and women, both neurologically, muscularly, hemostatically, as well as in terms of cell multiplication and differentiation. It is therefore necessary that a system can constantly regulate phosphorus and calcium in the body because maternal-fetal complications occur in the absence of early diagnosis. Several treatment options can be considered and offered to the patient, ranging from simple regular monitoring of serum calcium to selective parathyroidectomy, including drug treatment. Our clinical case illustrates an effective surgical treatment in the third trimester of pregnancy. Conclusion: Parathyroidectomy in the 3rd trimester of pregnancy is an effective therapy for the treatment of symptomatic primary hyperparathyroidism
The SciCryo Project and Cryogenic Scintillation of for Dark Matter
International audienceWe discuss cryogenic scintillation of Al2O3. Room-temperature measurements with α particles are first carried out to study effect of Ti concentration on response. Measurements under X-rays between room temperature and 10 K confirm a doubling of light output. The integration of a scintillation-phonon detector into an ionization-phonon dark matter search is underway, and the quenching factor for neutrons has been verified
First test of an enriched CdWO scintillating bolometer for neutrinoless double-beta-decay searches
For the first time, a cadmium tungstate crystal scintillator enriched in
Cd has been succesfully tested as a scintillating bolometer. The
measurement was performed above ground at a temperature of 18 mK. The crystal
mass was 34.5 g and the enrichment level ~82 %. Despite a substantial pile-up
effect due to above-ground operation, the detector demonstrated a high energy
resolution (2-7 keV FWHM in 0.2-2.6 MeV energy range), a powerful
particle identification capability and a high level of internal radiopurity.
These results prove that cadmium tungstate is an extremely promising detector
material for a next-generation neutrinoless double-beta decay bolometric
experiment, like that proposed in the CUPID project (CUORE Upgrade with
Particle IDentification)
- …