Workshop format and scope Expected write-up's Follow-up actions Report on Joint Machine-Experiment Workshop on Experimental Conditions and Beam-Induced Background Workshop format and scope Expected write-up's Follow-up actions

History, Scope of Workshop Organisation of such a workshop was encouraged by LHC MAC Scope: Combined LHC machine + experiments workshop to: review the experience from TEVATRON/RHIC/HERA see what we can expect and optimise from the machine side see what the LHC experiments require and provide as signals for optimisation Work together to optimise the running conditions aiming at: safe and stable operation with tolerable backgrounds and radiation optimisation of the physics potential (maximum integrated luminosity with acceptable background)  help anticipating issues related to beam conditions and elaborate a framework to attack such problems

Workshop Summary and Follow-up A workshop summary will be published within 2 weeks Executive summary (Organizers) Session summaries (Chairpersons) Session discussions (Sc. Secr.) Individual contributions (Speakers) A more exciting Workshop summary will be presented at an AB Seminar (15th of May, Helmut Burkhardt & MFL) Here, I focus on the more boring "executive" part of the workshop Disclaimer: this is still in draft form

Session 1

Session 2

Session 3 Followed by a closed summary session, 1 hour, Fr PM Andreas Morsch Followed by a closed summary session, 1 hour, Fr PM present: speakers, organizers, conveners, sc.secr., expt representatives, and more.

Coherent framework for understanding MIB For future work, a clear need and a request emerged for rationalisation of machine-induced background studies. It was demanded that the various contributors agree first on a set of configurations and a systematic strategy. This implies: 1. define few benchmark run scenari, i.e. optics, filling patterns, intensities, crossing schemes and ramped energy (LPC) 2. define collimator settings for each scenario (Collimation group) 3. IP-generated protons: a) generate/transport scattered protons from IPs to 1st restriction (TBD) b) shower generation by these protons and transport of particles (TBD) 4. produce vacuum profiles for the relevant sections based on best knowledge (AT-VAC). Here, only the missing pressure bump due to TCTs was identified. Future: include data. 5. produce collimator-induced halo particles, including quartic halo (Collimation group) 6. produce distant beam-gas particles and transport to the experimental interface plane (TBD) 7. simulate backgrounds within the experiments (experiments) new

UNDER DISCUSSION Future of MIBWG Machine-experiments communication is currently being discussed: proposal: concentrate as much as possible under LPC review role of LEMIC and WGs Embed MIB studies as a (long term) task force in LPC understand bkgs, using both measured data and simulation tools deploy/use a coherent machine-experiments model replaces (continues) currently existing and fruitful MIBWG (TS-LEA) actors of MIBWG are strongly encouraged to continue work within new organisation more people needed ? It is desirable that each experiment maintains (or strengthens) a small group of people to continuously address beam-induced background issues UNDER DISCUSSION

BKG F.O.M. signals to CCC It was agreed that a few figure-of-merit signals (2 to 4) would be provided by each experiment for the operators to tune the beam conditions in an efficient way. The meaning of the signals should be clearly defined and the sensitivity to types of backgrounds (e.g. beam 1 or beam 2, if applicable) clearly stated. The experiments and machine should agree on a common scale definition for these signals, with a universal meaning. The implementation of this scale and the algorithmic of the signals involved should be discussed with the LPC to ensure that a similar interpretation is indeed implemented by each experiment. For instance, will the signals be approximately linear with the current-normalised rates ? Or is a logarithmic scale more approriate ? (experiments)

Additional info from Expts to CCC In addition to these few bkg FOM signals, each experiment will provide a (possibly interactive) summary page about the status of their experiment that machine operators will use when discussions specific to that experiment are going on in the CCC. This should also be coordinated within the LPC in order to promote coherence among the experiments. For instance, it was suggested to include a pictorial view of the experiment around which the measured signals are displayed (experiments)

Collimators.... It was agreed that, in order not to create unnecessary background in the experiments (especially ALICE), the tertiary collimators should be put as far out as possible, such that the triplet magnets remain in the shadow of the TCTs. This depends on the beam configuration (energy, optics, beta*). It was agreed that the collimation group would provide AT-VAC with a list of elements that are expected to warm up significantly due to beam losses (which can change the local vacuum conditions due to outgassing).