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H8 protection
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Europe/Zurich
C. Ahdida, A. Colinet, M. Fraser, L. Nevay
Risk
There is a risk, due to bad settings to send the high intensity proton beam at 400GeV to H8, and potentially to EHN1.
Personnel protection mitigation measures
Radiation Protection Assessment of Worst Case Accidental Beam Losses in EHN1: https://edms.cern.ch/document/2366787/1
Estimation of Maximal Intensities in the EHN1 Beamlines in Case of Improper Use: https://edms.cern.ch/document/2263075/1
- The bend downstream the TAX is used to deflect particles and prevent propagation towards H8
- Small collimator with a fixed mask in TT82 attenuates the beam
- TAX aperture attenuates the beam
- LOKN system is used for personnel protection
- The SPS beam intensity is checked by LOKN
Today, the maximum primary beam intensity in H8 is 6.3e10p per spill after the TAX (case of 4mm diameter TAX + no Beryllium Attenuator).
It is considered that the attenuation is enough to reduce the worst-case accidental dose for H8 to below the annual limit of Radiation Workers. The attenuation is caused by the TAX aperture, and the fixed mask collimator.
The maximal beam intensities assume that the splitting is done correctly in TDC2 leading to a T4 intensity of 3e12 protons/spill. Considering a bad splitting would mean that double failures are considered.
Action Matthew: Perform a similar analysis with 4e13p dedicated beam.
Operational modes
Post LS3, SHiP and H8 cycles are exclusive. There is a need for reconfiguration of the beam lines before enabling to switch from one to the other.
Potentially, if attenuation were to be forced higher, then we could operate both lines in parallel. Nevertheless, this is not desirable as the wobbling configuration would be impacted.
Machine protection
More work needs to be done on the failure case before coming back to machine protection.
It is foreseen to install BLMs in H8. These BLMs would have to be connected to the same interlock as the BLMs in TDC2 and TCC2.
Action Laurie: Finalise the list of required BLMs + respective positions
Action Antoine: Once the list is ready, follow-up with Christos on connections to the BIS
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