Preparation of Nuclear Targets for Particle Accelerators edited by Jozef Jaklovsky

1982 ◽  
Vol 21 (4) ◽  
pp. 1049-1050
Author(s):  
H. L. Adair
Author(s):  
K. F. Russell ◽  
L. L. Horton

Beams of heavy ions from particle accelerators are used to produce radiation damage in metal alloys. The damaged layer extends several microns below the surface of the specimen with the maximum damage and depth dependent upon the energy of the ions, type of ions, and target material. Using 4 MeV heavy ions from a Van de Graaff accelerator causes peak damage approximately 1 μm below the specimen surface. To study this area, it is necessary to remove a thickness of approximately 1 μm of damaged metal from the surface (referred to as “sectioning“) and to electropolish this region to electron transparency from the unirradiated surface (referred to as “backthinning“). We have developed electropolishing techniques to obtain electron transparent regions at any depth below the surface of a standard TEM disk. These techniques may be applied wherever TEM information is needed at a specific subsurface position.


2019 ◽  
Vol 139 (9) ◽  
pp. 568-575
Author(s):  
Yusuke Sakamoto ◽  
Daisuke Ishizuka ◽  
Tetsuya Matsuda ◽  
Kazuhiro Izui ◽  
Shinji Nishiwaki

2019 ◽  
Vol 199 ◽  
pp. 01014
Author(s):  
K. Piscicchia ◽  
M. Bazzi ◽  
G. Belloti ◽  
A. M. Bragadireanu ◽  
D. Bosnar ◽  
...  

The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-rest, or low-momentum, K− interactions in light nuclear targets, with the aim to constrain the low energy QCD models in the strangeness sector. The 0 step of the experiment consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K− absorptions in H, 4He, 9Be and 12C, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K− captures. With AMADEUS step 1 a dedicated pure Carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K− nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{A_{{K^ - }n \to \Lambda {\pi ^ - }}}} \right|$ at $\sqrt s = 33\,MeV$ below the K̄N threshold is presented, in relation with the Λ(1405) properties studies. The analysis procedure adopted in the serarch for K− multi-nucleon absorption cross sections and Branching Ratios will be also described.


2020 ◽  
Vol 102 (12) ◽  
Author(s):  
Céline Bœhm ◽  
Céline Degrande ◽  
Jakub Scholtz ◽  
Aaron C. Vincent

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul B. Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  

AbstractSuperconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1–2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200–240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.


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