- Pb beam for open charm measurements (top priority)
https://cds.cern.ch/record/2799311?ln=en

- Pb for the nuclear fragmentation cross-section measurements for cosmic-ray physics

A) The LHC malfunctioning may impact the 2023 Pb run. The new injector schedule will be presented on September 1st. The Pb beam time allocated to NA61/SHINE will likely remain unchanged (four weeks) (private communication from BE colleagues).

B) Loosing two months of LHC protons in 2023 may cancel the Pb run in 2024, primarily for LHC and possibly for us. This should be taken into account in our planning. We will probably have more information on September 1st.

C) At the September SPSC, Rende will present two versions of the 2024 SPS schedule. One of them will include several days of oxygen in SPS after TS. Advocating for this version without reducing the 2024 Pb beam time would be important.
During several days of the oxygen beam, we could test the water target for the post-LS3 O+O running (the corresponding addendum is submitted to the September SPSC - https://cds.cern.ch/record/2867952?ln=en) and take the CR fragmentation data. This could be a several-day-long test run, which does not require the SPSC recommendation.

D) In the case of cancelling the Pb run 2024, we should request compensation for the lost ion beam time by having a four-week-long O beam time in 2024.

Dear Marek,

The present plan is to have a very brief period (several days) with Oxygen ion in the LHC (possibly also in the SPS if there is an interest and if it is compatible with the proton requests) in June 2024 and then to be ready for the Pb ion period in the LHC and the SPS-NA for the end of the 2024 run.
Following the issue in the LHC we may have a slightly longer LHC Pb ion run this year and discussions will start on the length of the ion run in 2024. However, to a certain extend the LHC Pb ion run is independent from the SPS-NA Pb ion run. Even if for the LHC we would decide not to run Pb ion in the 2024 it does not mean we will not run Pb ions for the SPS-NA. Four weeks sound reasonable and I do not expect issues for that, even if the LHC would run shorter or not at all with Pb ions in 2024.

I therefore can only recommend to clearly state your beam request (Pb ions and Oxygen ions) to the SPSC for discussion and recommendation to the RB.

With kind regards,

Rende

Dear Marek and all,

let me summarize the purpose of our meeting as I understand it from the short discussion with you:
While it is unclear whether and to what extent recent problems at the LHC beam may have
consequences for the SPS schedule in 2023 and 2024, it is certainly prudent to consider possible scenarios.

The main purpose of the meeting is therefore not to bring new physics arguments to the table. Rather,
the focus will be on asking how the SPSC-recommended physics program can be realized under evolving conditions.

I would find it very valuable to have all SPSC referees present in the meeting, so that we are all adequately briefed prior
to the September SPSC (there will be very little time for discussing NA61-related matters in that meeting). I would also find
it valuable to have at least one member of the NA61 CR-community present, since part of the discussion will be about
opportunities for the cosmic ray physics program of NA61.

However, insisting that everyone in cc joins the meeting may be an overconstraint and, given the content of the discussion, it may not be really necessary. I therefore suggest, Marek, that you fix the date of the meeting based on the replies that you have received by now.

Best regards, Urs

Dear All,

Let us meet on August 25 (Friday) at 16:00 Geneva time:

https://indico.cern.ch/event/1314821/

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