High Resolution High Thermal Conductivity Scintillator for XFEL Beam Diagnostics

The XFEL facility at SLAC is currently undergoing a major upgrade, where the soft X-ray repetition rate for LCLS II will be increase by almost 10,000 times, from 120 Hz to 1 MHz. The resulting high average power leads to new challenges for the survivability of beamline instrumentation, especially the sensors designed and implemented for quantitative assessment of the fundamental focal properties of the laser, for aligning X-ray instruments, and for conducting scientific experimental analysis. One of the critical components of the instrumentation is a scintillator which is vulnerable to thermal damage. RMD will address this challenge by innovatively integrating scintillator into material of high thermal conductivity in order to dissipate the intense localized heat. Two candidate materials will be evaluated for improving heat dissipation, both of which have the excellent bulk thermal conductivities. The scintillator will be grown as a transparent material using highly economic process. The proposed scintillator will be tailored to achieve high brightness and high spatial resolution while providing excellent X-ray absorption over a wide X-ray energy range. The proposed approach has numerous unique advantages and will effectively address specific needs of LCLS II. The goal of the proposed Phase I is to demonstrate feasibility of our concept. Specifically, in the Phase I, RMD Inc. will use special methods to grow scintillators and characterize their performance. Finite Element Analysis of the scintillator will be conducted to arrive at the design that can provide the desired thermal conductivity performance without degrading the spatial resolution or the response uniformity. The properties of the scintillator will be thoroughly characterized at RMD Inc. with X-rays, and then the feasibility will be tested at the XFEL beamline. Thus, successful development of the proposed scintillator will enable new avenues of research using LCLS II that benefit the public. For instance, in the development of new drugs (including COVID-19 related work), materials, and systems, all of which directly impact health care, our quality of life, and the widening of the US technology base. This work will also lead to advancements of technologies with significant commercial impact and will help maintain our nation’s technological edge over competing nations.