Research Notes and Documents

Tech Notes

• WF Calibration -- 5/4/18 Calibration of the UITF Wien Filter (WF) by adjusting the E-Field and B-Field to determine the velocity of the electron beam
• Spring 2018 QE vs. Charge & Fall 2016 QE vs. Charge -- 5/24/18 Plots of QE vs. Charge data from the CEBAF injector. The Spring 2018 plot corresponds to when the vertical WF was at 50 degrees and the horizontal WF was off. The Fall 2016 plot is the opposite with the horizontal WF at 50 degrees and the vertical WF was off.
• Magnetic field in front of photogun idea -- 5/25/18 An idea that I had that may solve the problem of ion back-bombardment due to ion creation downstream of the anode.
• Derivation of QE Formula -- 6/1/18 Derivation of the formula for photocathode QE based on electron current, laser power, and wavelength
• Magnetic Mirror Derivation - 9/19/18 Derived formulas for the criteria for ions to become trapped between two solenoids.
• BPM analysis of electron beam - 9/20/18 Derivation and plots involving the analysis of an electron beam using a beam position monitor (BPM). One can detect and identify ions in the beam based on their characteristic oscillation frequency. Derivation follows from Alex Chao's Fast Ion Instability lecture notes.
• Derivation of net force on ion - 10/3/18 Derivation of the net force on an ion between the biased anode and Magnetizing solenoid - should be helpful in determining the conditions for which an ion can be trapped between them.
• How to run GPT on the JLab farm - 1/18/19 A tutorial on how to use the JLab farm to run many GPT simulations at once. ***NOTE: This documentation is out of date as of 2022, as JLab has retired Auger and now uses Slurm to handle batch scripts. See iFarm documentation here: [1]
• Derivation of Electron-Ion Momenta during Ionization - 5/20/19 Deriving the initial and final momenta of the primary electron, secondary electron, and ion during ionization, provided the target molecule is at rest. Given the initial momentum of the primary electron (based on the beam energy) and the final momentum of the secondary electron (based on the differential energy cross section), the remaining values for momenta before and after the collision can be derived.

GTS Field Map Layout

• GTS Field Map Layout -- 10/11/18 Plot of the electric and magnetic fields through the first 1.2m of the GTS beamline using Gnuplot. The layout includes the field maps of the gun HV, biased anode, magnetizing (gun) solenoid, and the first two lenses (focusing solenoids), as well as vertical lines indicating positions of certain beamline elements (see GTS drawing)

July 2018 CEBAF Charge Lifetime Measurements

• QE vs. Charge -- Plot of QE vs Charge between 10:13:00 and 15:12:00 on 7/11/18
• Pickoff vs Inline -- Plot of pickoff power (to the photocathode) vs. inline power (before power meter) to determine power correction factor

Ion Bombardment of Solids Notes

• Intro and Sections 2.2-2.3 -- Completed 5/25/18
• Sections 2.4-2.6.2 -- Completed 5/30/18

Gun Voltage vs. Distance

• Voltage vs. Distance Line Plot -- 6/27/18 A line graph of voltage vs. distance using data from Gabriel
• Voltage vs. Distance 3D Plot -- 6/27/18 An extension of the graph above into 3D space. Apparently, the potential is symmetric about the z-axis...?

RGA Spectra, Ionization Cross Sections, and Ion Production Rate

• RGA Spectrum After 2 Days -- RGA Spectrum for gun chamber taken on 5/21/18 after prepping for 2 days, analyzed using gnuplot on 6/11/18. Each peak was fit using a gaussian function in order to determine the maximum and standard deviation of each peak.
• Ionization Cross Sections V1 -- 6/14/18, Updated on 6/15/18, Analysis of the RGA Spectrum "After 2 Days" (see below), a sample calculation for the ionization cross section of hydrogen gas, and a plot of ionization cross section vs. beam energy (electron kinetic energy).
• Ionization Cross Sections V2 -- 6/19/18 Updated document above to include section on numerical calculation of ionization rates.
• Ionization Cross Sections V3 -- 6/22/18 Updated document above to include tables of calculated values for the ion production rates of the gas species using normalized partial pressures.
• Ionization Cross Sections V4 -- 1/31/20 "If you try to fail and succeed, which have you done?" -George Carlin
• Ion Production Rate vs. Beam Energy -- 6/25/18 Formula derivation and plot of the ionization rate of gas species found in the "After 2 Days" RGA spectrum as a function of beam energy (gun voltage).
• Ion Production Rate vs. Beam Energy V2 -- 8/27/18 Updated document above. Included a section on normalizing IPR to beam current. Also changed both IPR vs. beam energy plots to log-log so that the effect of ionization cross section on IPR is clearly seen.

Oral Qualifier Paper and Presentation

• Oral Qualifier Paper -- 2/27/19 Contains current ionization Theory of Ghost Beam
• Oral Qualifier Presentation -- 2/27/19 Presentation on above paper

References

• References -- List of references in bibliography format. Updated on 9/4/18

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