[Moller] collimators

[Jay Benesch]

Mostly concerned with proton beams but some of the comments about 
tungsten may be of interest.  I hadn't thought about hydrogen 
embrittlement of tungsten via water cooling before seeing it herein. 
There was no issue that I'm aware of with the Qweak collimator but I 
pass this along nonetheless.

http://arxiv.org/abs/2502.03305

F. Pellemoine, K. Ammigan, C. Barbier, S. Bidhar, A. Casella, M. 
Calviani, C. Densham, P. Hurh, D. Kim, D. Liu, K. Lynch, S. Makimura, D. 
Senor, V. Shiltsev, D. Stratakis, J. Terry, K. Yonehara

     Designing a reliable target is already a challenge for MW-class 
facilities today and has led several major accelerator facilities to 
operate at lower than design power due to target concerns. With present 
plans to increase beam power for next generation accelerator facilities 
in the next decade, timely R and D in support of robust high power 
targets is critical to secure the full physics benefits of ambitious 
accelerator power upgrades. A comprehensive R and D program must be 
implemented to address the many complex challenges faced by multi MW 
beam intercepting devices. This roadmap is envisioned to be helpful to 
the DOE-OHEP office when planning and prioritizing future R and D 
activities as well as leveraging synergies across the Office of Science. 
The roadmap will be extremely beneficial to the broader (external to DOE 
HEP) HPT community by communicating OHEP s high level strategy and 
objectives for HPT R and D and highlighting possible opportunities for 
collaboration.