scholarly journals Dielectric-Filled Reentrant Cavity Resonator as a Low-Intensity Proton Beam Diagnostic

Instruments ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 24 ◽  
Author(s):  
Sudharsan Srinivasan ◽  
Pierre-André Duperrex
Keyword(s):  
Resonance Frequency ◽  
Proton Beam ◽  
Second Harmonic ◽  
Cavity Resonator ◽  
Beam Current ◽  
Dielectric Thickness ◽  
Medical Treatment Facility ◽  
Beam Currents ◽  
Paul Scherrer ◽  
Non Destructive

Measurement of the proton beam current (0.1–40 nA) at the medical treatment facility PROSCAN at the Paul Scherrer Institut (PSI) is performed with ionization chambers. To mitigate the scattering issues and to preserve the quality of the beam delivered to the patients, a non-interceptive monitor based on the principle of a reentrant cavity resonator has been built. The resonator with a fundamental resonance frequency of 145.7 MHz was matched to the second harmonic of the pulse repetition rate (72.85 MHz) of the beam extracted from the cyclotron. This was realized with the help of ANSYS HFSS (High Frequency Structural Simulator) for network analysis. Both, the pickup position and dielectric thickness were optimized. The prototype was characterized with a stand-alone test bench. There is good agreement between the simulated and measured parameters. The observed deviation in the resonance frequency is attributed to the frequency dependent dielectric loss tangent. Hence, the dielectric had to be resized to tune the resonator to the design resonance frequency. The measured sensitivity performances were in agreement with the expectations. We conclude that the dielectric reentrant cavity resonator is a promising candidate for measuring low proton beam currents in a non-destructive manner.

scholarly journals Non-Interceptive Beam Current and Position Monitors for a Cyclotron Based Proton Therapy Facility

2021 ◽  
Author(s):  
◽  
Sudharsan Srinivasan
Keyword(s):  
Proton Therapy ◽  
Second Harmonic ◽  
Beam Quality ◽  
Cavity Resonator ◽  
Beam Current ◽  
Cavity Resonators ◽  
Position Information ◽  
Beam Position ◽  
And Performance ◽  
Proton Therapy Facility

In PSI’s dedicated proton therapy facility PROSCAN a pulsed 250 MeV proton beam is delivered by a superconducting cyclotron. During the proton-irradiation treatments, there is a need to accurately measure beam current, in the range of 0.1-10 nA, and beam position (required accuracy 0.5 mm). The beam current is directly associated with the dose-rate in the treatment and the beam position with the quality of the dose distribution in the patient. However, the presently used measurements compromise the beam quality. Nevertheless, it is a necessity to perform these measurements online and with minimal beam disturbance. This thesis reports on the development of two types of cavity resonators to perform non-interceptive measurements of these beam parameters, within the required accuracy. For beam current measurements, a single cavity resonator has been built. For the beam position measurements, a cavity resonator consisting of four separate segments has been built. Both cavity resonators have been tuned to the second harmonic of the beam pulse rate, i.e., 145.7 MHz. In test bench experiments and with proton beams, a good agreement between the expected and measured sensitivity of these resonators has been found. The cavity used to measure beam current can measure currents down to 0.15 nA with a resolution of 0.05 nA. The cavity for measuring beam position delivers position information with the required accuracy and resolution demands of 0.5 mm. The design, tests and performance in the beam as well as special applications, future improvements and limitations are discussed.

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

scholarly journals Emittance measurements of the ACCEL K250 superconducting medical cyclotron at Paul Scherer institute

2006 ◽  
Vol 21 (1) ◽  
pp. 58-60
Author(s):  
Dragan Toprek
Keyword(s):  
Proton Beam ◽  
Beam Profile ◽  
Paul Scherrer Institute ◽  
Superconducting Cyclotron ◽  
Paul Scherrer ◽  
Quadrupole Method

The results of beam profile measurements of the proton beam of the ACCEL K250 superconducting cyclotron at the Paul Scherrer Institute are presented in this paper. Beam emittances in both horizontal and vertical planes are estimated by the varying quadrupole method.

scholarly journals Second-harmonic-generation enhancement in cavity resonator integrated grating filters

2019 ◽  
Vol 44 (21) ◽  
pp. 5198
Author(s):  
François Renaud ◽  
Antoine Monmayrant ◽  
Stéphane Calvez ◽  
Olivier Gauthier-Lafaye ◽  
Anne-Laure Fehrembach ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Cavity Resonator

scholarly journals Use of Nonlinear Optics for Assessment of Cable Polymer Aging

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Kaylee Rellaford ◽  
Dallin Smith ◽  
Alexander Farnsworth ◽  
Shane Drake ◽  
Hoon Lee ◽  
...  
Keyword(s):  
Service Use ◽  
Second Harmonic ◽  
Protective Role ◽  
Electric Power Research Institute ◽  
Proof Of Concept ◽  
Elongation At Break ◽  
Chlorosulfonated Polyethylene ◽  
Polymer Aging ◽  
Non Destructive ◽  
Destructive Methods

Polymer jackets play an important protective role in distribution cabling by providing structure and resistance to moisture, heat, and exposure to harmful chemicals. Current methods of structural assessment, such as elongation at break (E-at-B), are inherently destructive. While other non-destructive methods such as indenter evaluation are available, they are not suitable for in-service use. We propose that second harmonic generation (SHG) could provide a non-destructive means of characterizing the aging of chlorosulfonated polyethylene (CSPE) cable jackets. SHG was used to study cables previously aged and characterized by the Electric Power Research Institute (EPRI). Comparative data between the SHG results and indenter modulus tests suggest that SHG can be used to qualitatively differentiate between minimally and significantly aged CSPE cable jackets. The results of this proof-of-concept study suggest additional work that could be done to better understand the mechanisms of the aging of CSPE cable jackets and how SHG could be used to monitor the aging process.

scholarly journals (Invited) Second Harmonic Generation: A Powerful Non-Destructive Characterization Technique for Dielectric-on-Semiconductor Interfaces

2020 ◽  
Vol MA2020-01 (15) ◽  
pp. 1050-1050
Author(s):  
Irina Ionica ◽  
Dimitrios Damianos ◽  
Anne Kaminski ◽  
Danièle Blanc-Pélissier ◽  
Gerard Ghibaudo ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Semiconductor Interfaces ◽  
Characterization Technique ◽  
Non Destructive ◽  
Non Destructive Characterization

Current stability to improve AMS precision for cosmogenic 10Be applications

2021 ◽  
Author(s):  
Ana Carracedo Plumed ◽  
Derek Fabel ◽  
Richard Shanks
Keyword(s):  
Metal Matrix ◽  
Ion Beam ◽  
Beam Current ◽  
Ion Sources ◽  
Precipitation Process ◽  
Case Scenario ◽  
Series Of Experiments ◽  
Counting Statistics ◽  
Beam Currents ◽  
Cosmogenic 10Be

<p>With the present AMS <sup>10</sup>Be uncertainties (~2% best case scenario) and the increasing need for more precise cosmogenic <sup>10</sup>Be data it has become imperative to improve AMS measurements. Precision depends on counting statistics which in turn depend on ion beam current stability and sample longevity. The ion beam currents are dependent on the metal matrix in which BeO is dispersed; the matrix:BeO ratio; homogeneity of the mixture and the packing of the AMS cathode. We aim to understand the effect of cathode homogeneity in generating stable beam currents. We have performed a series of experiments using different metal matrices (Nb, Ag, Fe) in different forms (solid and in solution). The metals have been added to different stages of the sample precipitation process and both BeO and Be(OH)<sub>2</sub> have been pressed into AMS cathodes and analysed at SUERC. We will discuss results of these experiments and introduce an innovative use of polyoxometalates (molibdanate and niobate) to create a homogeneous compound that has the potential to generate stable ion beam currents from sputter ion sources.</p>

Annihilation Behaviors of Athermal ω-Phase Crystals Due to Electron Irradiation

2000 ◽  
Vol 6 (4) ◽  
pp. 362-367 ◽  
Author(s):  
Hajime Matsumoto ◽  
Eiichi Sukedai ◽  
Hatsujiro Hashimoto
Keyword(s):  
Electron Beam ◽  
Electron Irradiation ◽  
Beam Current ◽  
Dark Field ◽  
Electron Beam Current ◽  
Ω Phase ◽  
Observation Methods ◽  
Incubation Periods ◽  
Beam Currents

AbstractAnnihilation behaviors of athermal ω-phase crystals formed by cooling at 131 K for 10.8 ks under four different electron irradiation conditions of acceleration voltages of 200 kV and 160 kV, and beam currents of approximately 20 pA/cm2 and 5 pA/cm2 were investigated using in situ dark field and HREM observation methods at 131 K. The effect of acceleration voltages on the lifetimes is recognized, i.e., in the case of approximately equal electron beam current, lifetimes at 200 kV become shorter than those at 160 kV. Also, lifetimes depend on the electron beam current at 200 kV, i.e., the higher the beam currents, the shorter the lifetimes become. However, no distinct dependence can be seen at 160 kV. Since annihilations of athermal ω-phase crystals begin after the electron irradiation for a certain period in each condition, which depends on acceleration voltages and beam currents, it is suggested that the annihilation behaviors have incubation periods.

The use of a Perovskite crystal as a detector for proton beam current

1992 ◽  
Vol 39 (1) ◽  
pp. 25-28 ◽  
Author(s):  
P.E. Cruvinel ◽  
S. Mascarenhas ◽  
J. Miranda ◽  
R.G. Flocchini
Keyword(s):  
Proton Beam ◽  
Beam Current ◽  
Perovskite Crystal
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