T2/M9 Vacuum Situation - Update to Schedule 120

[Science Division]

Dear TRIUMF Users, Experimenters, Operators and Staff,

As you know we have been struggling with a serious vacuum leak in the 
T2/M9 indium seal and the Accelerator Division has carefully evaluated 
the situation, carried out tests, and made plans and provisions. As 
indicated earlier, the leak appears to clearly be temperature sensitive, 
and has deteriorated over the last few weeks. A decision has been made 
(please see also the statement from the Head of the Accelerator Division 
Lia Merminga, below) and we have to proceed for the remainder of the 
year (Schedule 120) without the T2 target. Moreover, the T2/M9 vacuum 
seal will be replaced in the upcoming shutdown, and M9 will be blanked off.

There are consequences to this decision:
• No M9 operation
• Extended shutdown and delayed start-up of schedule 120 for the meson 
hall user, translating into some cuts and shifts of experiments (the 
effected experiments have been informed)
• An updated schedule is available on the web page 
(https://mis.triumf.ca/schedule/view?schedule=120&revision=ACTIVE 
<https://mis.triumf.ca/schedule/view?schedule=120&revision=ACTIVE>)

I apologise for the inconvenience and count on your understanding for 
the delay in this technically challenging situation. We are also 
developing plans who to address these reoccurring issues in the mid- and 
long-term.

Thank you and best regards,
Jens Dilling
(sent by Niki Martin)

Lia Merminga’s (Head, Accelerator Division) statement:

During the past week we have collected data and observations which 
indicate that the present vacuum level is marginal and incompatible with 
smooth beam delivery, and can not be sustained during the fall run. 
Further, the cyclotron vacuum can not be isolated from BL1A in the short 
term.

Based on these data and the analysis of the M9T2 joint by the Remote 
Handling Group, we have decided to blank off the M9 channel at T2 during 
the September mini-shutdown, without the removal of magnets Q1/Q2. 
Assuming one iteration of a blank off is successful, beam production is 
expected to start by the afternoon of October 19th (October 17-19 BL1A 
start up). The T2 target will remain out for the remaining of the fall 
schedule.