First Results from the AMoRE-Pilot neutrinoless double beta decay experiment

The Advanced Molybdenum-based Rare process Experiment (AMoRE) aims to search for neutrinoless double beta decay (0$\nu\beta\beta$) of $^{100}$Mo with $\sim$100 kg of $^{100}$Mo-enriched molybdenum embedded in cryogenic detectors with a dual heat and light readout. At the current, pilot stage of the AMoRE project we employ six calcium molybdate crystals with a total mass of 1.9 kg, produced from $^{48}$Ca-depleted calcium and $^{100}$Mo-enriched molybdenum ($^{48\textrm{depl}}$Ca$^{100}$MoO$_4$). The simultaneous detection of heat(phonon) and scintillation (photon) signals is realized with high resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin temperatures. This stage of the project is carried out in the Yangyang underground laboratory at a depth of 700 m. We report first results from the AMoRE-Pilot $0\nu\beta\beta$ search with a 111 kg$\cdot$d live exposure of $^{48\textrm{depl}}$Ca$^{100}$MoO$_4$ crystals. No evidence for $0\nu\beta\beta$ decay of $^{100}$Mo is found, and a upper limit is set for the half-life of 0$\nu\beta\beta$ of $^{100}$Mo of $T^{0\nu}_{1/2} > 9.5\times10^{22}$ y at 90% C.L.. This limit corresponds to an effective Majorana neutrino mass limit in the range $\langle m_{\beta\beta}\rangle\le(1.2-2.1)$ eV

Structural study of alpha-Bi2O3 under pressure

An experimental and theoretical study of the structural properties of monoclinic bismuth oxide (alpha-(BiO3)-O-2) under high pressures is here reported. Both synthetic and mineral bismite powder samples have been compressed up to 45 GPa and their equations of state have been determined with angle-dispersive x-ray diffraction measurements. Experimental results have been also compared with theoretical calculations which suggest the possibility of several phase transitions below 10 GPa. However, experiments reveal only a pressure-induced amorphization between 15 and 25 GPa, depending on sample quality and deviatoric stresses. The amorphous phase has been followed up to 45 GPa and its nature discussed.Financial support from the Spanish Consolider Ingenio 2010 Program (MALTA Project No. CSD2007-00045) is acknowledged. This work was also supported by Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) under project 201050/2012-9, Spanish MICINN under projects MAT2010-21270-C04-01/03/04, Spanish MINECO under project CTQ2012-36253-C03-02, by Generalitat Valenciana through project GVA-ACOMP2013- 012 and from Vicerrectorado de Investigaci on dePereira, ALJ.; Errandonea, D.; Beltrán, A.; Gracia, L.; Gomis Hilario, O.; Sans, JA.; García-Domene, B.... (2013). Structural study of alpha-Bi2O3 under pressure. Journal of Physics: Condensed Matter. 25(47):475402-1-475402-12. https://doi.org/10.1088/0953-8984/25/47/475402S475402-1475402-12254

Up- and Downconversion Luminescence Properties of Nd3+ Ions Doped in Bi2O3–BaO–B2O3 Glass System

Physical, optical, and luminescence properties of Nd3+ ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd2O3 concentrations in compositions (40-x)B2O3 : 40Bi2O3 : 20BaO : xNd2O3 (where x = 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between 4F3/2 → 4I9/2 (900 nm), 4F3/2 → 4I11/2 (1,060 nm), and 4F3/2 → 4I13/2 (1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm (λex=591 nm). The processes are associated with excited state absorption (ESA) from 4F3/2 level to 4D3/2 level and it is the radiative decay from the 4D3/2 to ground levels (4D3/2 → 4I13/2) which are responsible for the emission at 394 nm

Up-and Downconversion Luminescence Properties of Nd 3+ Ions Doped in Bi 2 O 3 -BaO-B 2 O 3 Glass System

Physical, optical, and luminescence properties of Nd 3+ ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd 2 O 3 concentrations in compositions (40-x)B 2 O 3 : 40Bi 2 O 3 : 20BaO : xNd 2 O 3 (where x = 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between 4 F 3/2 → 4 I 9/2 (900 nm), 4 F 3/2 → 4 I 11/2 (1,060 nm), and 4 F 3/2 → 4 I 13/2 (1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm ( ex = 591 nm). The processes are associated with excited state absorption (ESA) from 4 F 3/2 level to 4 D 3/2 level and it is the radiative decay from the 4 D 3/2 to ground levels ( 4 D 3/2 → 4 I 13/2 ) which are responsible for the emission at 394 nm