We generate a continuous-wave (cw) cold methyl cyanide (CH(3)CN) beam by using an L-shaped bent quadrupole electrostatic guide (i.e., by a low-pass energy or velocity filtering), and use a photo-ionized time-of-flight mass-spectrometer method to experimentally measure and study the dependences of the longitudinal and transverse temperatures of the guided CH(3)CN beam and its guiding efficiency on the guiding voltage. We find a new scaling law: the longitudinal and transverse temperatures (T(z),T(rho)) of the guided CH(3)CN beam are proportional to the guiding voltage (T(z),T(rho) proportional to V(guide)), and further verify another scaling law: the molecular guiding efficiency eta is proportional to the square of the guiding voltage (eta proportional to V2(guide)). We also obtain some simulated results consistent with our experimental ones. We also measure the divergent angle of the output molecular beam and study its dependence on the guiding voltage. Our study shows that when the guiding voltage is V(guide) = +/-1 kV, a cw cold CH(3)CN beam with a longitudinal temperature of approximately 500 mK and a transverse one of approximately 40 mK can be generated by our L-shaped electrostatic guide. The divergent angle of the output CH(3)CN beam is about 16.4 degrees as V(guide) = +/-4 kV. It is clear that such a resulting cold molecular beam has some important applications in the fields of cold molecular physics, physical chemistry and chemical physics, etc.
Radiation detectors are currently fabricated by a screen-print method at room temperature. However, this method has many disadvantages in terms of thickness control and electron trapping. We fabricated polycrystalline PbI2 films by a new sedimentation method and compared the results with those obtained by the existing screen-print (SP) method. We investigated the electrical and structural properties of the films. We fabricated 2 ×2 cm2 sample films with a thickness of about 200 µm. A field emission scanning electron microscopy (FE-SEM) analysis showed that these films were of higher density than those fabricated by a conventional SP method. We also measured the photosensitivity and dark current of the films. The photosensitivity of the films fabricated by the new sedimentation method was 4.8 pC/(mR·mm2), and the dark current was 2.2 pA/mm2 at 1.0 V/µm. The linearity of the film ranged from 3 to 12 mAs, which is promising for diagnostic radiography.
An array of square current-carrying wires is proposed to construct a two-dimensional (2D) array of surface magneto-optical traps and Ioffe magnetic ones for realizing a 2D lattice of Bose-Einstein condensations (BECs) on an atom chip. Our study shows that when a vertical homogeneous bias magnetic field is only used, the wires will form a 2D array of quadrupole magnetic traps, which can be used to construct 2D lattice of surface magneto-optical micro-traps. While another horizontal homogeneous bias field is added simultaneously, the above 2D array of quadrupole micro-traps will be changed as an array of surface Ioffe micro-traps, which can be used to form a 2D magnetic lattice and then realize a 2D array of BECs. The dynamic loading process of cold (87)Rb atoms from each micro-MOT into Ioffe micro-trap is studied by using Monte-Carlo simulations, and our results show that the scheme can be used to realize a natural and effective loading of cold atoms from 2D array of micro-MOTs into 2D array of Ioffe micro-traps, and the loading efficiency can be reach ~ 65%. Moreover, the positions of each BEC (or MOT) in 2D array of magnetic micro-traps can be controlled by adjusting the currents in the wires or by changing the additional vertical bias field.
Polycrystalline lead oxide (PbO) film is an excellent candidate material for a direct conversion X-ray detector. However, the thick-bulky film tends to significantly reduce the charge collection efficiency for recombination process, and the effective number of electron-hole pairs is lower than that of thin film, because it is difficult to fabricate high-dense and thick PbO films. In this paper, we first synthesized nano-sized PbO particles that could be used in a novel high-efficiency flat panel X-ray detector using a simple solution/combustion method. Energy dispersive X-ray spectrometry, X-ray diffraction, and field emission scanning electron microscopy were used to analyze the component ratio and morphology of the PbO particles as a function of annealing temperature. Then, 150-mm-thick PbO films were deposited on glass substrates using a particle-in-binder method at room temperature. The influences of annealing before deposition on the X-ray detection characteristics of the PbO films were investigated in detail. The key parameters-the dark current, X-ray sensitivity, signal-to-noise ratio, and signal decay-were measured. The annealing conditions strongly affected the electrical properties of the PbO films. The X-ray sensitivity of films annealed in oxygen gas increased dramatically with increasing annealing temperatures up to 500 C.
We present a summary of the Large Millimeter Telescope (LMT) Project and its current status. The LMT is a joint project of the University of Massachusetts (UMass) in the USA and the Instituto Nacional de Astrofísica, Optica y Electrónica (INAOE) in Mexico to build a 50m-diameter millimeter-wave telescope. The LMT site is at an altitude of 4600 m atop Volcán Sierra Negra, an extinct volcanic peak in the state of Puebla, Mexico, approximately 100 km east of the city of Puebla. Construction of the antenna steel structure has been completed and the antenna drive system has been installed. Fabrication of the reflector surface is underway. The telescope is expected to be completed in 2008.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.