Measurement of the quantum-mechanical phase in quantum matter provides the most direct manifestation of the underlying abstract physics. We used resonant x-ray scattering to probe the relative phases ...of constituent atomic orbitals in an electronic wave function, which uncovers the unconventional Mott insulating state induced by relativistic spin-orbit coupling in the layered 5d transition metal oxide Sr2IrO4. A selection rule based on intra-atomic interference effects establishes a complex spin-orbital state represented by an effective total angular momentum = 1/2 quantum number, the phase of which can lead to a quantum topological state of matter.
The possibility to probe new physics scenarios of light Majorana neutrino exchange and right-handed currents at the planned next generation neutrinoless double
β
decay experiment SuperNEMO is ...discussed. Its ability to study different isotopes and track the outgoing electrons provides the means to discriminate different underlying mechanisms for the neutrinoless double
β
decay by measuring the decay half-life and the electron angular and energy distributions.
We have studied the neutrino-less double beta decay(0νββ) of 48Ca with the CANDLES III system, which consists of CaF2(pure) scintillators. Rejection analyses for background events from radioactive ...contaminations in the CaF2(pure) scintillators were effective to reduce backgrounds in Qββ-value region. As the results, no events were observed in the region for the data of 131 days × 86 kg. It gave a lower limit 6.2 × 1022 year (90 % C.L.) for the half-life of 0νββ of 48Ca. For higher sensitive measurement of 48Ca 0νββ, we have developed new techniques for 48Ca enrichment and CaF2 scintillating bolometer. In this paper, we will also show current status of these techniques.
In a dedicated test setup at the Kamioka Observatory we studied pulse shape discrimination (PSD) in liquid xenon (LXe) for dark matter searches in the absence of an externally applied electric field. ...PSD in LXe was based on the observation that scintillation light from electron events was emitted over a longer period of time than that of nuclear recoil events, and our method used a simple ratio of early to total scintillation light emission in a single scintillation event. Requiring an efficiency of 50% for nuclear recoil retention we reduced the electron background by a factor of 7.7±1.1(stat)±0.61.2(sys)×10−2 at energies between 4.8 and 7.2keVee and 7.7±2.8(stat)±2.82.5(sys)×10−3 at energies between 9.6 and 12keVee for a scintillation light yield of 20.9photoelectrons/keVee. Further study was done by masking some of that light to reduce this yield to 4.6photoelectrons/keVee. Under these conditions the same method results in an electron event reduction by a factor of 2.4±0.2(stat)±0.20.3(sys)×10−1 for the lower of the energy regions above. We also observe that in contrast to nuclear recoils the fluctuations in our early to total ratio for electron events are larger than expected from statistical fluctuations.
A high performance distillation system to remove krypton from xenon was constructed, and a purity level of Kr/Xe
=
∼3
×
10
−12 was achieved. This development is crucial in facilitating ...high-sensitivity low-background experiments such as the search for dark matter in the universe.
We have studied the neutrino-less double beta decay(0νββ) of 48Ca by using CaF2(pure) scintillators. Analysis for rejection of backgrounds(212Bi→ 212Po events and 208Tl events) was effective to ...reduce backgrounds in Qββ-value region. No events are observed in the Qββ-value region for the data of 131 days × 86 kg. It gives a lower limit (90% confidence level) of (math) > 6.2 × 1022 year (preliminary) for the half-life of 0νββ of 48Ca.
Measurement of the background in the NEMO 3 double beta decay experiment Argyriades, J.; Arnold, R.; Augier, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2009, Letnik:
606, Številka:
3
Journal Article
Recenzirano
Odprti dostop
In the double beta decay experiment NEMO 3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO 3 to evaluate the ...backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment.
Structures of Zr
70Ni
20Al
10, Zr
70Cu
20Al
10, Zr
70Cu
30 and Zr
70Ni
30 amorphous alloys were analyzed by high-energy X-ray diffraction. The relatively stable Zr
2Cu amorphous alloy shows a local ...atom arrangement different from the Zr
2Cu crystalline phase. By contrast, the less stable Zr
70Ni
30 amorphous alloy has a structure similar to Zr
2Ni. In the Zr
70Cu
20Al
10 metallic glass, Zr–Al nearest neighbor pairs are introduced in the amorphous structure. In the Zr
70Ni
20Al
10 metallic glass, the strong correlation between Zr–Ni pairs is drastically modified by the formation of Zr–Al pairs. The presence of Zr–Al pairs in the ternary alloys suppresses the crystallization and stabilizes the glassy state.
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