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Developing a High Power Electron Developing a High Power Electron Paramagnetic Resonance (EPR) Spectrometer

• Justin Bricker Oxnard College (EE Major)

Justin Bricker, Oxnard College (EE Major)

• Mentor: Devin Edwards

F lt Ad i M k Sh i Ph i D t t

• Faculty Advisor: Mark Sherwin, Physics Department
• Funding Source: NSF, Keck Foundation

Background

What is EPR?

• Radiation source and detector

H i t t di ti T P l EPR E i t

• How spins react to radiation
• Free Electron Laser (FEL)

240 GHz kW power Two-Pulse EPR Experiment

• One pulse strikes the sample
• Second pulse strikes sample to re phase

240 GHz, kW power

• Fast spin dynamics  Ex. proteins
• Second pulse strikes sample to re-phase
• Spectrometer measures the “echo”

z x y x y x x

Our Focus

Sherwin Group’s Focus: D l th t l t

• Develop the two pulse system
• Samples with fast reaction time
• Create two very short pulses
• Reduce radiation leakage

Challenges of created two pulses

• FEL pulse is ~1μs, we need <5 ns
• Use switches activated by green

lasers lasers

• Many sources of background noise

1 μs

Pulse Slicing

FEL

On Switch

240 GHz Radiation Source

• wer

Off Switch

Sample

Time Po

FEL Radiation Beam Path

S3 FEL Radiation Source S3 S6 Source S2 S5 S6 S1 S4 Sample Green Laser Sample Green Laser Green Laser

Green Laser Beam Path

Green Laser On Switch Off Switch Prism First Pulse: Changing Length 1 ft.  1 ns

• ~4-8 ns pulses
• Want to increase variability

Two-Pulse Experiment p

Progress

• Altered and aligned green laser beam

g g

• Created diagrams of beam path for analysis

Progress

• Designed and constructed isolation boxes
• Designed and constructed radiation-

d i t ( it h’ h t) dumping apparatus (witch’s hat)

Radiation Dumping

FEL Radiation Radiation Source

• Without hat  radiation leaks into room, detector

Hat installed  radiation is absorbed reduces

• Hat installed  radiation is absorbed, reduces

background noise

Effect of Radiation Dumping: First On Switch Effect of Radiation Dumping: First On Switch

• Sufficiently minimizes

background noise

Conclusions and Outlook Conclusions and Outlook

Improvements This Summer: Improvements This Summer:

• Reduced background noise
• Improved green laser accuracy

Created diagrams for analysis

• Created diagrams for analysis

What’s Next

• Implement switch
• Increase pulse length variability
• Run two-pulse EPR experiment to

show improvements

Thank you! Thank you!

Acknowledgements: g

• The Mark Sherwin Research Group

Louis Claude Brunel, Devin Edwards, Sahar El Abbadi, Vihn Nguyen, Mark Sherwin, Susumu Takahashi

INSET P

• INSET Program

Ofelia Aguirre, Nick Arnold, Arica Lubin, Jens‐Uwe Kuhn

• Funding Sources

National Science Foundation, Keck Foundation