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Title: Novel Plasmonic Photocathodes for Electron-Ion Colliders

Abstract

Our aim was to explore new photocathode materials and schemes to develop strategies and technologies for next generation nuclear physics accelerator capabilities, particularly for Electron Ion Colliders (EIC). We successfully implemented an experimental setup for light incidence at an acute angle onto metallic photocathodes in UHV, in order to excite surface Plasmon resonance, hence increasing light absorption by the metallic surface and tested the photoemitted current. We successfully tested the setup with a hot cathode as well as Plasmonic silver-MgO samples and obtained excellent results. We extended our studies to shorter wavelengths to help defeat the work function of the metal. We also used oblique incidence thin film deposition onto gratings to achieve optimized Plasmonic excitation leading to stronger EM field and also lower emittance. We tested and used adequate software to model our samples and simulate our experimental results. We incorporated the concept of Fano resonances applied to gratings to better interpret our experimental results.

Authors:
 [1]
  1. College of William and Mary, Williamsburg, VA (United States)
Publication Date:
Research Org.:
College of William and Mary, Williamsburg, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1364407
Report Number(s):
DOE-CWM-SC-0012182
DOE Contract Number:
SC0012182
Resource Type:
Technical Report
Resource Relation:
Related Information: Tailored Fano resonance and localized electromagnetic field enhancement in Ag gratings, by Zhaozhu Li, J. Michael Klopf, Lei Wang, Kaida Yang & Rosa A. Lukaszew, Scientific Reports 7, Article number: 44335 (2017)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; metallic photocathodes; plasmonics; Fano resonance

Citation Formats

Lukaszew, Rosa Alejandra. Novel Plasmonic Photocathodes for Electron-Ion Colliders. United States: N. p., 2017. Web. doi:10.2172/1364407.
Lukaszew, Rosa Alejandra. Novel Plasmonic Photocathodes for Electron-Ion Colliders. United States. doi:10.2172/1364407.
Lukaszew, Rosa Alejandra. Tue . "Novel Plasmonic Photocathodes for Electron-Ion Colliders". United States. doi:10.2172/1364407. https://www.osti.gov/servlets/purl/1364407.
@article{osti_1364407,
title = {Novel Plasmonic Photocathodes for Electron-Ion Colliders},
author = {Lukaszew, Rosa Alejandra},
abstractNote = {Our aim was to explore new photocathode materials and schemes to develop strategies and technologies for next generation nuclear physics accelerator capabilities, particularly for Electron Ion Colliders (EIC). We successfully implemented an experimental setup for light incidence at an acute angle onto metallic photocathodes in UHV, in order to excite surface Plasmon resonance, hence increasing light absorption by the metallic surface and tested the photoemitted current. We successfully tested the setup with a hot cathode as well as Plasmonic silver-MgO samples and obtained excellent results. We extended our studies to shorter wavelengths to help defeat the work function of the metal. We also used oblique incidence thin film deposition onto gratings to achieve optimized Plasmonic excitation leading to stronger EM field and also lower emittance. We tested and used adequate software to model our samples and simulate our experimental results. We incorporated the concept of Fano resonances applied to gratings to better interpret our experimental results.},
doi = {10.2172/1364407},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jun 20 00:00:00 EDT 2017},
month = {Tue Jun 20 00:00:00 EDT 2017}
}

Technical Report:

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  • Our aim has been to explore new photocathode materials and schemes to develop strategies and technologies for next generation nuclear physics accelerator capabilities, particularly for Electron Ion Colliders (EIC). Thus, we investigated thin film deposition and ensuing properties for several adequate magnetic materials applicable to spin-polarized photocathodes. We also implemented a full experimental setup for light incidence at an acute angle onto the photocathode surface in order to excite surface Plasmon resonance hence increasing light absorption by a metallic surface. We successfully tested the setup with a thermionic cathode as well as Plasmonic silver-MgO samples and obtained very encouraging results.more » Our first results are very encouraging since the photocurrent measured on this preliminary plasmonic Ag-MgO sample under low power (~ 1mW) cw red light from a HeNe laser was 256 pA, thus two orders magnitude larger than that reported by others following also plasmonic approaches. We extended our studies to shorter wavelengths and we also started preliminary work on chemically ordered MnAl thin films –a component of the tertiary Ag-Mn-Al (silmanal) alloy in order to develop spin-polarized photocathodes capable of sustaining surface Plasmon resonance. It is worthwhile mentioning that a graduate student has been directly involved during this project ensuring the training of next generation of scientists in this area of research.« less
  • Electron-ion colliders (EIC) have been identified as an ideal tool to study the next frontier of nuclear physics – the gluon force that holds the building blocks of matter together, and which is a fundamental component of the theory of Quantum Chromodynamics (QCD). Future electron-ion colliders under consideration can be based on the Energy Recovery Linac (ERL) architecture. The beam lines for this architecture could be built of the newly developed Non-Scaling Fixed Field Alternating Gradient (NS FFAG) structure, so that they can transfer multiple energies within the same aperture. This structure allows for the use of compact, economical quadupolemore » permanent magnets. In this SBIR, we propose to design and to manufacture prototype quadrupole permanent magnets of focusing/defocusing combined function for use in this beam line. For our SBIR project, we proposed to design and build the focusing/defocusing quadrupole with a gradient strength of 50 T/m and with a beam gap of 16mm. The proposed permanent magnet material is SmCo because of its higher radiation resistance as compared to NdBFe2. The use of permanent magnets will reduce the overall cost. For Phase I, we took a recent design by Dr. Dejan Trbojevic, and reran Tosca code on the design to optimize the iron yoke with respect to the thickness of SmCo. We then fabricated one prototype focusing/defocusing combined function quadruple and measured field quality dG/Go. Our plan for Phase II is that, based on our Phase I prototype experience, we shall improve the design and fabricate a production quadruple, and design and incorporate coils for skew dipoles and normal quadrupole correctors, etc. In addition, we shall fabricate enough quadrupoles for one cell. The development of quadrupole permanent magnets is of fundamental importance for there application in the future electron-ion colliders. This accelerator structure will also advance the development of muon accelerators and allow for the development of compact, simplified, less expensive proton accelerators which will promote their use in areas such as proton cancer therapy, and for high-power proton drivers for tritium and neutron production, waste transmutation, driving a sub-critical nuclear reactor to produce energy, cargo contain inspection, and radioisotope production. Proton cancer therapy has been identified as a particularly attractive and viable commercial application for the immediate future.« less
  • The two photocathode test systems were modified, baked and recommissioned. The first system was dedicated to ion studies and the second to electron stimulated recovery (ESR) work. The demonstration system for the electron beam rejuvenation was set up, tested and demonstrated to one of the SSRL team (Dr. Kirby) during a site visit. The requisite subsystems were transferred to SSRL, installed and photoemission studies conducted on activated surfaces following electron beam exposure. Little surface chemistry change was detected in the photoemission spectra following the ESR process. The yield mapping system for the ion (and later, the electron beam rejuvenation) studiesmore » was implemented and use made routine. Ion species and flux measurements were performed for H, He, Ne, Ar, Kr and Xe ions at energies of 0.5, 1.0 and 2.0 kV. Gas induced photoyield measurements followed each ion exposure measurement. These data permit the extraction of photoyield induced change per ion (by species) at the measured energies. Electron beam induced rejuvenation was first demonstrated in the second chamber with primary electron beam energy and dependency investigations following. A Hiden quadrupole mass spectrometer for the electron stimulated desorption (ESD) measurements was procured. The UHV test systems needed for subsequent measurements were configured, baked, commissioned and utilized for their intended purposes. Measurements characterizing the desorption products from the ESD process and secondary electron (SE) yield at the surfaces of negative electron affinity GaAs photocathodes have been performed. One US Utility Patent was granted covering the ESR process.« less