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A. Abramowicz

Publications and source records attributed to A. Abramowicz.

3 recordsLinked to original sources

New candidate polymeric wavelength shifters for noble liquid detectors

Polymeric wavelength shifters are of particular interest for large liquid argon detectors. Inspired by the success of polyethylene naphthalate (PEN), other new polymers exhibiting a similar type of excimer fluorescence were investigated. We report on the preliminary results of the first cryogenic wavelength shifting test of a solution-cast film of PVN, poly(2-vinyl naphthalene). Significant brittleness was identified as a factor potentially limiting the use of PVN. However, clear signs of wavelength shifting were observed, with the overall efficiency and time response comparable to those of PEN.

astro-ph.IM

Development of wavelength-shifting PEN foils for next generation experiments

Polyethylene naphthalate (PEN) foils have been demonstrated as a wavelength shifter suitable for operation in liquid argon. At the same time, wavelength shifting efficiency of technical grades of PEN, commercially available on the market, is lower than that of tetraphenyl butadiene (TPB). This paper reports on an R&D program focused on exploring the intrinsic limitations of PEN and optimizing it for the highest achievable wavelength shifting efficiency.

astro-ph.IM

Properties of YBa$_2$Cu$_3$O$_{7-δ}$ films grown by pulsed laser deposition on CeO$_2$-buffered sapphire

In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7-δ}$ (YBCO) films on the r-cut sapphire substrates. To improve the matching of the lattice parameters between the substrate and the film we use CeO$_{2}$ buffer layer, recrystallized prior to the deposition of YBCO. The optimal thickness and temperature of recrystallization of the buffer layer is first determined using atomic force microscopy (AFM) and X-ray diffraction. Next, we use the AFM to examine the dependence of YBCO film roughness on the film thickness, and we study the homogeneity of magnetic flux penetration into the films by magneto-optical imaging. We find that the superconducting critical temperature and critical current density of these films are very similar to those of YBCO films grown on well-matched substrates. It appears that the microstructure of YBCO films is affected by structural defects in the buffer layer as well as variations in oxygen deficiency, which results in high values of critical current density suitable for application.

cond-mat.supr-con