In recent years, cooling technology for liquid xenon(LXe) detectors has advanced driven by the development of dark matter(DM) detectors with target mass in the 100–1000 kg range. The next generation of DM detectors b...In recent years, cooling technology for liquid xenon(LXe) detectors has advanced driven by the development of dark matter(DM) detectors with target mass in the 100–1000 kg range. The next generation of DM detectors based on LXe will be in the 50,000 kg(50 t)range requiring more than 1 k W of cooling power. Most of the prior cooling methods become impractical at this level.For cooling a 50 t scale LXe detector, a method is proposed in which liquid nitrogen(LN2) in a small local reservoir cools the xenon gas via a cold finger. The cold finger incorporates a heating unit to provide temperature regulation. The proposed cooling method is simple, reliable, and suitable for the required long-term operation for a rare event search. The device can be easily integrated into present cooling systems, for example the ‘‘Cooling Bus’ ’employed for the Panda X I and II experiments. It is still possible to cool indirectly with no part of the cooling or temperature control system getting in direct contact with the clean xenon in the detector. Also, the cooling device can be mounted at a large distance, i.e., the detector is cooled remotely from a distance of 5–10 m. The method was tested in a laboratory setup at Columbia University to carry out different measurements with a small LXe detector and behaved exactly as predicted.展开更多
The convergent iterative procedure for solving the groundstate Schrodinger equation is extended to derive the excitation energy and the wavefunction of the low-lying excited states. The method is applied to the one-di...The convergent iterative procedure for solving the groundstate Schrodinger equation is extended to derive the excitation energy and the wavefunction of the low-lying excited states. The method is applied to the one-dimensional quartic potential problem. The results show that the iterative solution converges rapidly when the coupling g is not too small.展开更多
We propose a simple set of hypotheses governing the deviations of the leptonic mapping matrix from the Harrison-Perkins-Scott （HPS） form. These deviations are supposed to arise entirely from a perturbation of the ma...We propose a simple set of hypotheses governing the deviations of the leptonic mapping matrix from the Harrison-Perkins-Scott （HPS） form. These deviations are supposed to arise entirely from a perturbation of the mass matrix in the charged lepton sector. The perturbing matrix is assumed to be purely imaginary （thus maximally T-violating） and to have a strength in energy scale no greater （but perhaps smaller） than the muon mass. As we shall show, it then follows that the absolute value of the mapping matrix elements pertaining to the tau lepton deviate by no more than O（（mμ/mτ）^2） ≈ 3.5 ×10^-3 from their HPS values. Assuming that （mμ/mτ）^2 can be neglected, we derive two simple constraints on the four parameters θ12,θ23, θ31, and δ of the mapping matrix. These constraints are independent of the details of the imaginary T-violating perturbation of the charged lepton mass matrix. We also show that the e and μ parts of the mapping matrix have a definite form governed by two parameters α and β; any deviation of order mμ/mτ can be accommodated by adjusting these two parameters.展开更多
eAbstract We extend the T violating model of the paper on ＂Hidden symmetry of the CKM and neutrinomapping matrices＂ by assuming its T-violating phases X↑ and X↓ to be large and the same, with X = X↑ = X↓. In thi...eAbstract We extend the T violating model of the paper on ＂Hidden symmetry of the CKM and neutrinomapping matrices＂ by assuming its T-violating phases X↑ and X↓ to be large and the same, with X = X↑ = X↓. In this case, the model has 9 real parameters： aT, α↑,β↑,ξ↑,η↑T for the T-quark sector, α↓,β↓,ξ↓,η↓, for the sector and a common X- We examine whether these nine parameters are compatible with ten observables： the six quark masses and the four real parameters that characterize the CKM matrix （i.e., the Jarlskog invariant and three Eulerian angles）. We find that this is possible only if the T violating phase X is large, between -120^o to -135^o. In this strong T violating model, the smallness of theJarlskog invariant 3 × 10^-5 ismainly accounted for by the large heavy quark masses, with mc/mt〈ms/mb≈0.02, as well as the near completeoverlap of t and b quark, with （c｜b）=-0.04.展开更多
基金the Ministry of Science and Technology of China(No.2016YFA0400301)the grants for the XENON Dark Matter Project。
文摘In recent years, cooling technology for liquid xenon(LXe) detectors has advanced driven by the development of dark matter(DM) detectors with target mass in the 100–1000 kg range. The next generation of DM detectors based on LXe will be in the 50,000 kg(50 t)range requiring more than 1 k W of cooling power. Most of the prior cooling methods become impractical at this level.For cooling a 50 t scale LXe detector, a method is proposed in which liquid nitrogen(LN2) in a small local reservoir cools the xenon gas via a cold finger. The cold finger incorporates a heating unit to provide temperature regulation. The proposed cooling method is simple, reliable, and suitable for the required long-term operation for a rare event search. The device can be easily integrated into present cooling systems, for example the ‘‘Cooling Bus’ ’employed for the Panda X I and II experiments. It is still possible to cool indirectly with no part of the cooling or temperature control system getting in direct contact with the clean xenon in the detector. Also, the cooling device can be mounted at a large distance, i.e., the detector is cooled remotely from a distance of 5–10 m. The method was tested in a laboratory setup at Columbia University to carry out different measurements with a small LXe detector and behaved exactly as predicted.
基金This research was supported in part by the U.S. Department of Energy （Grant No DE-FG02-92ER-40699） and the National Natural Science Foundation of China （Grant No 10547001）.
文摘The convergent iterative procedure for solving the groundstate Schrodinger equation is extended to derive the excitation energy and the wavefunction of the low-lying excited states. The method is applied to the one-dimensional quartic potential problem. The results show that the iterative solution converges rapidly when the coupling g is not too small.
文摘We propose a simple set of hypotheses governing the deviations of the leptonic mapping matrix from the Harrison-Perkins-Scott （HPS） form. These deviations are supposed to arise entirely from a perturbation of the mass matrix in the charged lepton sector. The perturbing matrix is assumed to be purely imaginary （thus maximally T-violating） and to have a strength in energy scale no greater （but perhaps smaller） than the muon mass. As we shall show, it then follows that the absolute value of the mapping matrix elements pertaining to the tau lepton deviate by no more than O（（mμ/mτ）^2） ≈ 3.5 ×10^-3 from their HPS values. Assuming that （mμ/mτ）^2 can be neglected, we derive two simple constraints on the four parameters θ12,θ23, θ31, and δ of the mapping matrix. These constraints are independent of the details of the imaginary T-violating perturbation of the charged lepton mass matrix. We also show that the e and μ parts of the mapping matrix have a definite form governed by two parameters α and β; any deviation of order mμ/mτ can be accommodated by adjusting these two parameters.
基金Supported in part by the U.S. Department of Energy (DE-FG02-92-ER40699)
文摘eAbstract We extend the T violating model of the paper on ＂Hidden symmetry of the CKM and neutrinomapping matrices＂ by assuming its T-violating phases X↑ and X↓ to be large and the same, with X = X↑ = X↓. In this case, the model has 9 real parameters： aT, α↑,β↑,ξ↑,η↑T for the T-quark sector, α↓,β↓,ξ↓,η↓, for the sector and a common X- We examine whether these nine parameters are compatible with ten observables： the six quark masses and the four real parameters that characterize the CKM matrix （i.e., the Jarlskog invariant and three Eulerian angles）. We find that this is possible only if the T violating phase X is large, between -120^o to -135^o. In this strong T violating model, the smallness of theJarlskog invariant 3 × 10^-5 ismainly accounted for by the large heavy quark masses, with mc/mt〈ms/mb≈0.02, as well as the near completeoverlap of t and b quark, with （c｜b）=-0.04.
