•A large custom cryogen-free cryostat has been designed and built in order to operate the CUORE detector.•The CUORE cryostat has a 1 m3 experimental volume and is able to host a tonne-scale ...bolometric detector.•The CUORE cryostat guarantees a low noise and low radioactivity environment, needed to search for 0nbb.•The CUORE detector has been cooled down to 8.3 mK and steadily operated at 15 mK, proving the success of the cryostat.
The CUORE experiment is the world’s largest bolometric experiment. The detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg. CUORE is presently taking data at the Laboratori Nazionali del Gran Sasso, Italy, searching for the neutrinoless double beta decay of 130Te. A large custom cryogen-free cryostat allows reaching and maintaining a base temperature of ∼10 mK, required for the optimal operation of the detector. This apparatus has been designed in order to achieve a low noise environment, with minimal contribution to the radioactive background for the experiment. In this paper, we present an overview of the CUORE cryostat, together with a description of all its sub-systems, focusing on the solutions identified to satisfy the stringent requirements. We briefly illustrate the various phases of the cryostat commissioning and highlight the relevant steps and milestones achieved each time. Finally, we describe the successful cooldown of CUORE.
Single nucleon pickup reactions were performed with a 18.1 MeV/nucleon (14)O beam on a deuterium target. Within the coupled reaction channel framework, the measured cross sections were compared to ...theoretical predictions and analyzed using both phenomenological and microscopic overlap functions. The missing strength due to correlations does not show significant dependence on the nucleon separation energy asymmetry over a wide range of 37 MeV, in contrast with nucleon removal data analyzed within the sudden-eikonal formalism.
MINOS is a new apparatus dedicated to in-beam nuclear structure experiments with low-intensity exotic beams in inverse kinematics at intermediate energies above 150MeV/nucleon. The device is composed ...of a thick liquid-hydrogen target coupled to a compact time projection chamber (TPC) serving as a vertex tracker. Either used for in-beam gamma spectroscopy of bound excited states or invariant-mass spectroscopy of unbound states, MINOS aims at improving the luminosity by a very significant factor compared to standard solid-target material experiments while improving experimental resolutions.
We present deep, accurate, and homogeneous multiband optical (, , ,) photometry of the Carina dwarf spheroidal galaxy, based on more than 4000 individual CCD images from three different ground-based ...telescopes. Special attention was given to the photometric calibration, and the precision for the , , and bands is generally better than 0.01 mag. We have performed detailed comparisons in the , - , and , - color-magnitude diagrams (CMDs) between Carina and three old, metal-poor Galactic globular clusters (GGCs, M53, M55, M79). We find that only the more metal-poor GCs (M55, Fe/H = -1.85 ; M53, Fe/H = -2.02 dex) provide a good match with the Carina giant branch. We have performed a similar comparison in the , - CMD with three intermediate-age clusters (IACs) of the Small Magellanic Cloud (Kron 3, NGC 339, Lindsay 38). We find that the color extent of the subgiant branch (SGB) of the two more metal-rich IACs (Kron 3, Fe/H = -1.08 ; NGC339, Fe/H = -1.36 dex) is smaller than the range among CarinaAs intermediate-age stars. Moreover, the slope of the RGB of these two IACs is shallower than the slope of the Carina RGB. However, the ridge line of the more metal-poor IAC (Lindsay 38, Fe/H = -1.59 dex) agrees quite well with the Carina intermediate-age stars. These findings indicate that CarinaAs old stellar population is metal-poor and appears to have a limited spread in metallicity (deltaFe/H = 0.2-0.3 dex). The CarinaAs intermediate-age stellar population can hardly be more metal-rich than Lindsay 38, and its spread in metallicity also appears modest. We also find that the synthetic CMD constructed assuming a metallicity spread of 0.5 dex for the intermediate-age stellar component predicts evolutionary features not supported by observations. In particular, red clump stars should attain colors that are redder than red giant stars, but this is not seen. These results are at odds with recent spectroscopic investigations suggesting that Carina stars cover a broad range in metallicity (deltaFe/H approx 1-2 dex). We also present a new method to estimate the metallicity of complex stellar systems using the difference in color between the red clump and the middle of the RR Lyrae instability strip. The observed colors of CarinaAs evolved stars indicate a metallicity of Fe/H = -1.70 A+/- 0.19 dex , which agrees quite well with spectroscopic measurements.
ABSTRACT We have performed accurate iron abundance measurements for 44 red giants (RGs) in the Carina dwarf spheroidal (dSph) galaxy. We used archival, high-resolution spectra (R ∼ 38,000) collected ...with UVES at ESO/VLT either in slit mode (five RGs) or in fiber mode (39 RGs, FLAMES/GIRAFFE-UVES). The sample is more than a factor of 4 larger than any previous spectroscopic investigation of stars in dSphs based on high-resolution (R≥38000) spectra. We did not impose the ionization equilibrium between neutral and singly ionized iron lines. The effective temperatures and the surface gravities were estimated by fitting stellar isochrones in the V,B - V color-magnitude diagram. To measure the iron abundance of individual lines we applied the LTE spectrum-synthesis fitting method using MARCS model atmospheres of appropriate metallicity. For the 27 stars for which we measured both Fe I and Fe II abundances, we found evidence of NLTE effects between neutral and singly ionized iron abundances. The difference is ∼0.1 dex, on average, but steadily increases when moving from the metal-rich to the metal-poor regime. Moreover, the two metallicity distributions differ at the 97% confidence level. Assuming that the Fe II abundances are minimally affected by NLTE effects, we corrected the Fe I stellar abundances using a linear fit between Fe I and Fe II stellar abundance determinations. We found that the Carina metallicity distribution based on the corrected Fe I abundances (44 RGs) has a weighted mean metallicity of Fe/H = -1.80 and a weighted standard deviation of σ = 0.24 dex. The Carina metallicity distribution based on the Fe II abundances (27 RGs) gives similar estimates (Fe/H = -1.72, σ = 0.24 dex). The current weighted mean metallicities are slightly more metal-poor when compared with similar estimates available in the literature. Furthermore, when we restricted our analysis to stars with the most accurate iron abundances, ∼20 Fe I and at least three Fe II measurements (15 stars), we found that the range in iron abundances covered by Carina RGs (∼1 dex) agreed quite well with similar estimates based on high-resolution spectra; however, it is a factor of 2-3 smaller than abundance estimates based on the near-infrared calcium triplet. This finding supports previous estimates based on photometric metallicity indicators.
We report new photometry for 10 globular clusters in M31, observed to a uniform depth of four orbits in F555W (V) and F814W (I) using WFPC2 on board the Hubble Space Telescope (HST). In addition, we ...have reanalyzed HST archival data of comparable quality for two more clusters. A special feature of our analysis is the extraordinary care taken to account for the effects of blended stellar images and the required subtraction of contamination from the field stellar populations in M31 in which the clusters are embedded. We thus reach 1 mag fainter than the horizontal branch (HB), even in unfavorable cases. We also show that an apparent peculiar steep slope of the HB for those clusters with blue HB stars is actually due to blends between blue HB stars and red giants. We present the color-magnitude diagrams (CMDs) and discuss their main features in comparison with the properties of the Galactic globular clusters. This analysis is augmented with CMDs previously obtained and discussed on eight other M31 clusters. We report the following significant results: (1) The loci of the red giant branches give reliable photometric metallicity determinations that generally compare very well with ground-based integrated spectroscopic and photometric measures, as well as giving good reddening estimates. (2) The HB morphologies follow the same behavior with metallicity as the Galactic globular clusters, with indications that the second-parameter effect can be present in some clusters of our sample. However, at Fe/H =~ -1.7 we observe a number of clusters with red HB morphology such that the HB type versus Fe/H relationship is offset from that of the Milky Way (MW) and resembles that of the Fornax dwarf spheroidal galaxy. One explanation for the offset is that the most metal-poor M31 globular clusters are younger than their MW counterparts by 1-2 Gyr; further study is required. (3) The MV(HB) versus Fe/H relationship has been redetermined, and the slope (~0.20) is very similar to the values derived from RR Lyrae stars in the MW and the LMC. The zero point of this relation (MV = 0.51 at Fe/H = -1.5) is based on the assumed distance modulus (m - M)0(M31) = 24.47 ± 0.03, and is consistent with the distance scale that places the LMC at (m - M)0(LMC) = 18.55.
PDF
