Monte Carlo modeling of small photon fields: Quantifying the impact of focal spot size on source occlusion and output factors, and exploring miniphantom design for small-field measurements

2009 ◽  
Vol 36 (7) ◽  
pp. 3132-3144 ◽  
Author(s):  
Alison J. D. Scott ◽  
Alan E. Nahum ◽  
John D. Fenwick
Keyword(s):  
Monte Carlo ◽  
Focal Spot ◽  
Field Measurements ◽  
Spot Size ◽  
Small Field ◽  
Focal Spot Size ◽  
Monte Carlo Modeling ◽  
Output Factors ◽  
The Impact

Effects of Laser Beam Focusing Characteristics on Laser-Induced Breakdown Spectra

2020 ◽  
pp. 000370282096143
Author(s):  
David M. Surmick ◽  
Leon Taleh ◽  
Noureddine Melikechi
Keyword(s):  
Focal Spot ◽  
Ionic Species ◽  
Spot Size ◽  
Focal Spot Size ◽  
Breakdown Spectroscopy ◽  
Beam Focusing ◽  
Laser Focusing ◽  
Laser Induced Breakdown ◽  
The Impact ◽  
Sample Distance

The impact of altering laser focusing conditions on laser-induced breakdown spectroscopy experiments is investigated under ambient Earth laboratory and simulated Martian atmospheres. Experiments were performed in which the focal spot size was varied on a sample by altering the lens to sample distance with respect to targets of interest. Samples investigated include aluminum, copper, and steel. Specific neutral and ionic transitions of each sample were monitored. Atomic and ionic emissions show different intensity peak distributions along the varying lens to sample distance. Ionic species have peak emissions when laser plasma is initiated with a focused spot within the sample in ambient Earth laboratory air, while atomic emissions have peak intensities several millimeters deeper into a sample. In simulated Martian atmospheres, atomic emissions are observed to peak when the laser is focused within the sample, while ionic emissions have peak intensities when the laser is focused near the surface of a sample.

On the relationships between electron spot size, focal spot size, and virtual source position in Monte Carlo simulations

2011 ◽  
Vol 38 (3) ◽  
pp. 1579-1586 ◽  
Author(s):  
E. Sterpin ◽  
Y. Chen ◽  
W. Lu ◽  
T. R. Mackie ◽  
G. H. Olivera ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Focal Spot ◽  
Spot Size ◽  
Virtual Source ◽  
Source Position ◽  
Focal Spot Size

The impact of focal spot size on clinical images

2009 ◽  
Author(s):  
Sinead M. Gorham ◽  
Patrick C. Brennan
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Focal Spot Size ◽  
Clinical Images ◽  
The Impact

Computational Technique for the Qualification of Focal Spot Size and Shape of Industrial Radioscopy Equipment Using Star Patterns

2020 ◽  
Vol 78 (4) ◽  
pp. 479-486
Author(s):  
Marcela Tatiana Fernandes Beserra ◽  
◽  
Ricardo Tadeu Lopes ◽  
Davi Ferreira de Oliveira ◽  
Claudio Carvalho Conti ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Computational Technique ◽  
Focal Spot Size ◽  
Size And Shape

scholarly journals Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

2011 ◽  
Vol 29 (3) ◽  
pp. 345-351 ◽  
Author(s):  
C.M. Brenner ◽  
J.S. Green ◽  
A.P.L. Robinson ◽  
D.C. Carroll ◽  
B. Dromey ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Laser Pulse Energy ◽  
Laser Energy ◽  
Spot Size ◽  
Proton Flux ◽  
Focal Spot Size ◽  
Order Of Magnitude ◽  
Laser Focal Spot ◽  
Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

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