1 / 15

NdFeB Radiation Effects and RHIC Tunnel Radiation Levels

NdFeB Radiation Effects and RHIC Tunnel Radiation Levels. Summary of some existing papers and Paul Bergh’s “Special Studies”. Some Papers People have Found. NB: the Chen paper cites a dozen others that look interesting but I haven’t downloaded yet!.

evansdustin
Télécharger la présentation

NdFeB Radiation Effects and RHIC Tunnel Radiation Levels

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NdFeB Radiation Effects and RHIC Tunnel Radiation Levels Summary of some existing papers and Paul Bergh’s “Special Studies” Stephen Brooks, eRHIC FFAG meeting

  2. Some Papers People have Found NB: the Chen paper cites a dozen others that look interesting but I haven’t downloaded yet! “SNS” paper turned out to just re-use LANL neutron irradiation data Stephen Brooks, eRHIC FFAG meeting

  3. Room Temperature Plots Temnykh (blocks) Ito et al. (cylinders) 1kGy = 100krad 104Gy = 1000krad Stephen Brooks, eRHIC FFAG meeting

  4. Interpolated Losses at 10kGy “SH” is high max temperature grade; “Z” is low thermal coefficient grade eRHIC Shin-Etsu quote used N36SH (~$1/cc) N36Z (~$1.30/cc) Stephen Brooks, eRHIC FFAG meeting

  5. Shin-Etsu N Grade B-H Curves Stephen Brooks, eRHIC FFAG meeting

  6. What “H” vs “V” Means (Temnykh) H (bad) V (good) Stephen Brooks, eRHIC FFAG meeting

  7. “Load Lines” – Geometry Matters From Chen et al. Stephen Brooks, eRHIC FFAG meeting

  8. Irradiation Rate in RHIC Tunnel? • Paul Bergh sometimes leaves TLD badges in the tunnel for ~2 weeks in “Special Studies” • Badges record following in rem or mrem: • “Deep photon” gammas • TLD 8814 neutrons (lower energy band) • Optionally CR-39 neutrons (higher energy band) • Roughly convert to Grays with • Grays = (gamma+(TLD8814+CR39)/5)/100 Stephen Brooks, eRHIC FFAG meeting

  9. Irradiation Rates in RHIC Tunnel CR-39 saturated Stephen Brooks, eRHIC FFAG meeting

  10. Total Radiation Dose for eRHIC? • Maximum measured dose rates of 0.2Gy/day • 50Gy per 250 day operational year • 1kGy over 20 operational years of 250 days • If using 1kGy can divide values in previously-shown table by 10 • eRHIC magnets will be everywhere around the ring, but TLD studies data is only at a few points, so be cautious! Stephen Brooks, eRHIC FFAG meeting

  11. Pragmatic Conclusion for eRHIC • N48 is bad: ~10% flux loss expected • N40 and N32Z are marginal, ~1% loss • N40SH and SmCo both look good, <0.1% loss • This makes one more confident about the cheaper N36SH grade used in eRHIC costing • Ito’s N32Z result is surprisingly bad • Must check where on B-H curve eRHIC magnet designs are in terms of permeance=|B/H| Stephen Brooks, eRHIC FFAG meeting

  12. Empirical formula/mechanism? • Domain flipping could be caused by localised heating, or some other triggered “tunnelling” phenomenon • Should expect degradation rates of the form k1exp(-k2H) where H is “potential barrier” • Temnykh defines it in terms of “de-magnetising temperature” margin (but why not exp(-kH/T)?) • Could also use DH to demagnetisation on the B-H curve Stephen Brooks, eRHIC FFAG meeting

  13. From Temnykh Stephen Brooks, eRHIC FFAG meeting

  14. N42SH-R Thermal Behaviour Stephen Brooks, eRHIC FFAG meeting

  15. Phantom Reference via EEC Stephen Brooks, eRHIC FFAG meeting

More Related