Minutes and Summary

Main purpose of the meeting: To discuss the current status of PbPb running and planning for the G7

LPC 29 May 2026

Present (P = in person): Chiara Zampolli (P), Martijn Mulders (P), Eric Torrence (P),  Silvia Pisano (P), Krystian Roslon(P), Julia Negro (P), Archie Sharma (P), Witold Kozanecki (P), Roderik Bruce (P), Flavio Pisani (P), Ivan Amos Cali (P), Stefano Redaelli (P),  Tomasz Bold, Dragoslav Lazic, Mirko Pojer, Federica Oliva, Matthew Nguyen, Richard Hawkings, Kartik Deepak Bhide, Riccardo Longo, Joanna Wańczyk, Juan Estban Muller, Antonio Sbrizzi, Giulia Ripellino, Filip Moortgat, Maciej Trzebinski

LPC intro (Chiara Zampolli)

Roderik Bruce: just one addition to the meetings - we also plan a background study group meeting probably on the 8th of June. 

LHCb (Flavio Pisani)

Roderik Bruce: you could even try parking. Even 25 sigma is not fully open, so you could have a very deep hit on the TCT, and you could still see something. Depending on the shape of the halo, it is possible we didn’t see any changes in our test if there is something very focused hitting deep in the TCT. The funny thing is that in the simulations, we do see something from the TCT that gives you a spot exactly there. So there's something to understand somewhere.

[... some more discussion about the statistical precision of the numbers… ]

Flavio Pisani: for the SMOG program LHCb is now injecting Methane for the first time, for carbon-lead interactions. We also injected methane for the BGI. We use methane now for PbPb and then we will go back to He, which is also a first in PbPb. 

Chiara Zampolli: this is for which kind of physics?

Flavio Pisani: I am not an expert, but it is basically the only way you can have carbon-Pb interactions. 

ATLAS (Eric Torrence)

[.. some discussion about the HI schedule and MD3..]

Roderik Bruce clarifies that the 25/50ns test would be ‘the same’ setup as in 2025 but hopefully with a better intensity and more statistics. 

Eric Torrence states that ATLAS probably will not be able to run with 25ns bunch spacing, but they have developed some new ideas on how to deal with this and it would be useful to do more tests, even if it is to prove that they cannot run with 25ns. Roderic Bruce: that would be very important input to have.  
 
CMS (Archie Sharma)

Chiara Zampolli: so the impact of the forward pixel issues is a loss in acceptance? Or a loss in data taking because you need time to configure? 

Giulia Negro: both. Well, it depends. We will define a strategy. At the moment we are still doing tests at the beginning of each fill, so basically we are not taking data for some time in the beginning to make it work. And then it also has an effect on reconstruction efficiency, in those rings.

ALICE (Silvia Pisano)

Slide 2 - [.. some discussion about the fact that the values found in the current angular scan will change during LS3..] Roderik Bruce: it is a good guess to start from these values in Run 4, but not be surprised if you find that there are some shifts. 

Slide 3 - Chiara Zampolli: will you test a higher data taking rate during PbPb? Silvia Pisano: no, we don’t want to do that. The 23 kilohertz is not only optimizing TPC stability, but also reconstruction and calibration. We just want to maximize data taking.