AC Josephson properties of phase slip lines in wide tin films

Current steps in the current-voltage characteristics of wide superconducting Sn films exposed to a microwave irradiation were observed in the resistive state with phase slip lines. The behaviour of the magnitude of the steps on the applied irradiation power was found to be similar to that for the current steps in narrow superconducting channels with phase slip centers and, to some extent, for the Shapiro steps in Josephson junctions. This provides evidence for the Josephson properties of the phase slip lines in wide superconducting films and supports the assumption about similarity between the processes of phase slip in wide and narrow films.Comment: 7 pages, 2 figures, to be published in Supercond. Sci. Techno

Optically Pumped Polarized 3^3He++^{++} Ion Source Development for RHIC/EIC

The proposed polarized $^3$He$^{++}$ acceleration in RHIC and the future Electron-Ion Collider will require about $2\times10^{11}$ ions in the source pulse. A new technique had been proposed for production of high intensity polarized $^3$He$^{++}$ ion beams. It is based on ionization and accumulation of the $^3$He gas (polarized by metastability-exchange optical pumping and in the 5 T high magnetic field) in the existing Electron Beam Ion Source (EBIS). A novel $^3$He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized $^3$He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3--5 T field has been developed. The $^3$He polarization 80--85\% (and sufficiently long $\sim30$ min relaxation time) was obtained in the \lq\lq{open}\rq\rq\ cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and $^3$He $^4$He absolute nuclear polarimeter at 6 MeV $^3$He$^{++}$ beam energy is also presented.Comment: 9 pages, 11 figure

Low-temperature heat capacity of fullerite C₆₀ doped with nitrogen

The heat capacity Cm of polycrystalline fullerite C₆₀ doped with nitrogen has been measured in the temperature interval 2–13 K. The contributions to the heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C₆₀ molecules (Einstein contribution), and from the motion of the N₂ molecules in the octahedral cavities of the C₆₀ lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first-order phase transformation that had been detected earlier in the dilatometric investigation of the orientational N₂–C₆₀ glass. A possible explanation of this fact is proposed

Low temperature heat capacity of fullerite C60 doped with nitrogen

The heat capacity Cm of polycrystalline fullerite C60 doped with nitrogen has been measured in the temperature interval 2 - 13 K. The contributions to heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C60 molecules (Einstein contribution) and from the motion of the N2 molecules in the octahedral cavities of the C60 lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first - order phase transformation that had been detected earlier in the dilatometric investigation of the orientational N2-C60 glass. A possible explanation of this fact is proposed.Comment: 4 pages, 2 figures, to be published in Fiz. Nizk. Temp. (Low Temp. Phys.

Economic Ideas and Institutional Change: Evidence from Soviet Economic Discourse 1987-1991

In recent years, institutional and evolutionary economists have become increasingly aware that ideas play an important role in economic development. In the current literature, the problem is usually elaborated upon in purely theoretical terms. In the present paper it is argued that ideas are always also shaped by historical and cultural factors. Due to this historical and cultural specificity theoretical research must be supplemented by historical case studies. The paper analyses the shift in ideas that took place in Soviet economic thought between 1987 and 1991. This case study, it is argued, may contribute to our understanding of the links between ideas and institutions. More specifically, it sheds new light on the issue of whether the evolution of economic ideas is pathdependent, so that they change only incrementally, or whether their development takes place in a discontinuous way that can best be compared with revolutions

Development of a polarized 3He++ ion source for the EIC

© Owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). The capability of accelerating a high-intensity polarized 3He ion beam would provide an effective polarized neutron beam for new high-energy QCD studies of nucleon structure. This development is essential for the future Electron Ion Collider, which could use a polarized 3He ion beam to probe the spin structure of the neutron. The proposed polarized 3He ion source is based on the Electron Beam Ion Source (EBIS) currently in operation at Brookhaven National Laboratory. 3He gas would be polarized within the 5 T field of the EBIS solenoid via Metastability Exchange Optical Pumping (MEOP) and then pulsed into the EBIS vacuum and drift tube system where the 3He will be ionized by the 10 Amp electron beam. The goal of the polarized 3He ion source is to achieve 2.5 × 1011 3He++/pulse at 70% polarization. An upgrade of the EBIS is currently underway. An absolute polarimeter and spin-rotator is being developed to measure the 3He ion polarization at 6 MeV after initial acceleration out of the EBIS. The source is being developed through collaboration between BNL and MIT

Development and beam test of a continuous wave radio frequency quadrupole accelerator

The front end of any modern ion accelerator includes a radio frequency quadrupole (RFQ). While many pulsed ion linacs successfully operate RFQs, several ion accelerators worldwide have significant difficulties operating continuous wave (CW) RFQs to design specifications. In this paper we describe the development and results of the beam commissioning of a CW RFQ designed and built for the National User Facility: Argonne Tandem Linac Accelerator System (ATLAS). Several innovative ideas were implemented in this CW RFQ. By selecting a multisegment split-coaxial structure, we reached moderate transverse dimensions for a 60.625-MHz resonator and provided a highly stabilized electromagnetic field distribution. The accelerating section of the RFQ occupies approximately 50% of the total length and is based on a trapezoidal vane tip modulation that increased the resonator shunt impedance by 60% in this section as compared to conventional sinusoidal modulation. To form an axially symmetric beam exiting the RFQ, a very short output radial matcher with a length of 0.75βλ was developed. The RFQ is designed as a 100% oxygen-free electronic (OFE) copper structure and fabricated with a two-step furnace brazing process. The radio frequency (rf) measurements show excellent rf properties for the resonator, with a measured intrinsic Q equal to 94% of the simulated value for OFE copper. An O^{5+} ion beam extracted from an electron cyclotron resonance ion source was used for the RFQ commissioning. In off-line beam testing, we found excellent coincidence of the measured beam parameters with the results of beam dynamics simulations performed using the beam dynamics code TRACK, which was developed at Argonne. These results demonstrate the great success of the RFQ design and fabrication technology developed here, which can be applied to future CW RFQs