scholarly journals Theoretical Modeling for the Thermal Stability of Solid Targets in a Positron-Driven Muon Collider

2021 ◽  
Vol 42 (12) ◽  
Author(s):  
Gianmario Cesarini ◽  
Mario Antonelli ◽  
Fabio Anulli ◽  
Matteo Bauce ◽  
Maria Enrica Biagini ◽  
...  
Keyword(s):  
Temperature Increase ◽  
Positron Beam ◽  
Spot Size ◽  
High Energy ◽  
Target System ◽  
Beam Spot ◽  
Thermomechanical Stress ◽  
Beam Spot Size ◽  
Muon Collider ◽  
Muon Production

AbstractA future multi-TeV muon collider requires new ideas to tackle the problems of muon production, accumulation and acceleration. In the Low EMittance Muon Accelerator concept a 45 GeV positron beam, stored in an accumulation ring with high energy acceptance and low angular divergence, is extracted and driven to a target system in order to produce muon pairs near the kinematic threshold. However, this scheme requires an intensity of the impinging positron beam so high that the energy dissipation and the target maintenance are crucial aspects to be investigated. Both peak temperature rises and thermomechanical shocks are related to the beam spot size at the target for a given material: these aspects are setting a lower bound on the beam spot size itself. The purpose of this paper is to provide a fully theoretical approach to predict the temperature increase, the thermal gradients, and the induced thermomechanical stress on targets, generated by a sequence of 45 GeV positron bunches. A case study is here presented for Beryllium and Graphite targets. We first discuss the Monte Carlo simulations to evaluate the heat deposited on the targets after a single bunch of 3 × 1011 positrons for different beam sizes. Then a theoretical model is developed to simulate the temperature increase of the targets subjected to very fast sequences of positron pulses, over different timescales, from ps regime to hundreds of seconds. Finally a simple approach is provided to estimate the induced thermomechanical stresses in the target, together with simple criteria to be fulfilled (i.e., Christensen safety factor) to prevent the crack formation mechanism.

DETECTION LIMIT FOR A VERY THIN BACKING FILM

1994 ◽  
Vol 04 (01) ◽  
pp. 1-7 ◽  
Author(s):  
KEIZO ISHII ◽  
HIKONOJO ORIHARA ◽  
YOSHIHIRO IWATA ◽  
KOTARO BESSHO
Keyword(s):  
Thin Film ◽  
Detection Limit ◽  
Spot Size ◽  
High Energy ◽  
High Energy Region ◽  
Beam Spot ◽  
Polyvinyl Formal ◽  
Beam Spot Size ◽  
Γ Rays ◽  
Mev Protons

Detection limit for thin backing films is formulated. A polyvinyl formal film of ~ 0.14µm was bombarded with 3 MeV protons and continuos backgrounds were measured with a Si(Li) detector. A large constant background of a high energy region (≥6 keV ) was interpreted as the Compton tail due to the 440 keV γ-rays from the excited state of 23Na which contaminated the surface of a carbon collimator placed just in front of a target. The detection limits of this thin film, under the condition of the beam spot size 6 mmϕ without collimator, are estimated for the elements of atomic number Z=10~55 and the minimum detection limit is calculated to be 4×10−12 g for Z=28~34.

PLANAR JOSEPHSON JUNCTIONS FABRICATED BY FOCUSED-ION BEAM

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3359-3360 ◽  
Author(s):  
Hye-Won Seo ◽  
Quark Y. Chen ◽  
Chong Wang ◽  
Wei-Kan Chu ◽  
T. M. Chuang ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Josephson Junctions ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Spot Size ◽  
Physical Significance ◽  
Fabrication Technique ◽  
Beam Spot ◽  
Beam Spot Size ◽  
Current Voltage

We have fabricated nano-scaled planar superconductor-insulator-superconductor Josephson junctions using focused ion beam (FIB) with beam spot size ~5 nm . To study the effectiveness of this fabrication technique and for the purpose of comparisons, a variety of samples have been made based on high temperature superconducting (HTS) YBa2Cu3O7-δ electrodes. The insulators are either vacuum or silicon dioxide. The samples showed current-voltage (IV) characteristics typical of a resistively shunted junction (RSJ). We will discuss various aspects of the processing methods and the physical significance of the junction characteristics.

Development of a high-current microbeam system

2014 ◽  
Vol 24 (03n04) ◽  
pp. 101-110 ◽  
Author(s):  
S. Matsuyama ◽  
K. Ishii ◽  
S. Suzuki ◽  
A. Terakawa ◽  
M. Fujiwara ◽  
...  
Keyword(s):  
Quadrupole Doublet ◽  
Spot Size ◽  
Beam Current ◽  
Chemical State ◽  
High Current ◽  
Rigid Support ◽  
Beam Spot ◽  
X Ray ◽  
Beam Spot Size

We report on the development of a high-current microbeam system for wavelength-dispersive X-ray micro particle-induced X-ray emission (WDX-[Formula: see text]-PIXE) for chemical state mapping. The microbeam system is composed of two slits and a quadrupole doublet lens mounted on a heavy rigid support. The microbeam system is installed immediately after a switching magnet. A beam brightness of [Formula: see text] is obtained at a half-divergence of 0.1 mrad. A beam current of more than 300 pA is obtained for object sizes of [Formula: see text] with a half-divergence of 0.2 mrad, which corresponds to a beam spot size of [Formula: see text]. The calculated spot size of the beam was [Formula: see text] and the measured spot size was [Formula: see text]. The WDX-[Formula: see text]-PIXE system with the microbeam system is now operational.

Push beam spot-size dependence of atom transfer in a double magneto-optical trap setup

2013 ◽  
Vol 84 (7) ◽  
pp. 073102 ◽  
Author(s):  
S. P. Ram ◽  
S. K. Tiwari ◽  
S. R. Mishra ◽  
H. S. Rawat
Keyword(s):  
Size Dependence ◽  
Optical Trap ◽  
Spot Size ◽  
Atom Transfer ◽  
Magneto Optical Trap ◽  
Beam Spot ◽  
Beam Spot Size

Defect Sizing in Pipeline Welds: What Can We Really Achieve?

2004 ◽  
Author(s):  
Michael Moles
Keyword(s):  
Fracture Mechanics ◽  
Time Of Flight ◽  
Spot Size ◽  
Height Measurement ◽  
Beam Spot ◽  
Analysis Techniques ◽  
Time Of Flight Diffraction ◽  
Beam Spot Size ◽  
Weld Inspection ◽  
Focused Transducers

Pipelines are now using Fitness-For-Service (FFS) for accept/reject of weld defects. FFS requires accurate measurement of defect height for Fracture Mechanics assessments. The standard pipeline weld inspection technique of radiography is incapable of such measurements. However, the newer technique of ultrasonics can measure defect height, in principle. Initially ultrasonic amplitude methods were used for height measurement, but these proved unreliable. Now diffraction methods, especially Time-Of-Flight-Diffraction (TOFD), are being used in conjunction. This paper reviews previous work — mainly large nuclear studies like PISC II — and published pipeline sizing studies. The best nuclear sizing was within a few millimetres, using diffraction. In contrast to nuclear, pipeline AUT uses zone discrimination, focused transducers, much thinner material and simpler analysis techniques. Current accuracies are typically ± 1 mm (terminology undefined), which correlates with the beam spot size and typical weld pass. Requests for accuracies of ± 0.3 mm are probably unachievable, though future R&D should significantly improve pipeline sizing.

SU-F-T-167: Measurement of Proton Beam Spot Size Using a 2D Ion Chamber Array for Daily QA

2016 ◽  
Vol 43 (6Part15) ◽  
pp. 3500-3500
Author(s):  
N Thorne ◽  
A Kassaee
Keyword(s):  
Proton Beam ◽  
Spot Size ◽  
Beam Spot ◽  
Ion Chamber ◽  
Beam Spot Size

Improvement of ion beam brightness by reducing voltage ripple of an electrostatic accelerator for microbeam focusing by a triplet quadrupole lens system having large spherical aberration coefficient

2013 ◽  
Vol 23 (03n04) ◽  
pp. 171-181 ◽  
Author(s):  
S. Matsuyama ◽  
K. Watanabe ◽  
K. Ishii ◽  
A. Terakawa ◽  
M. Fujisawa ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Spherical Aberration ◽  
Ion Beam ◽  
Spot Size ◽  
Beam Current ◽  
Lens System ◽  
Beam Spot ◽  
Beam Spot Size ◽  
Voltage Ripple ◽  
Terminal Voltage

The microbeam system at Tohoku University was upgraded to a triplet lens system aiming at applying to the analysis of sub-micron features. The triplet lens system has a higher demagnification than the existing doublet system. However, the introduction of the triplet system also resulted in larger chromatic and spherical aberration coefficients. To overcome these problems, the energy resolution of the accelerator was improved by developing a terminal voltage stabilization system. The energy resolution of the accelerator was improved to 1 × 10−5 ΔE/E, which resulted in an increase in the brightness of the beam. The beam brightness was 2.3 pA Δ μm−2 Δ mrad−2 Δ MeV− and was higher in the central region. The effects of the increased chromatic and spherical aberration were mitigated by restricting the divergence angle without reducing the beam current. A beam spot size of 0.6 × 0.8 μm2 was obtained with a beam current of 150 pA.

Sign in / Sign up

Export Citation Format

Share Document