ATLAS Forward Project (AFP) Technical review outcome Review done on (morning) September 2013, see agenda Reviewers: Francis Anghinolfi; Massimiliano Ferro-Luzzi; Ana Henriques (chair); Steve McMahon; Ashutosh Kotwal; Srini Rajagopalan

Main topics discussed 17th September – Introduction/physics motivation – Movable beam pipe – Silicon Tracker – Timing detectors (phase 0+1) – Common infrastructures (DAQ, trigger, DCS, services) – Manpower, Timescale – Closed session with reviewers -> questions prepared 18th September (morning) – Closed session with reviewers – Open session discussing questions/answers by reviewers/AFP community

This review proved to be very useful The material prepared was of high quality and it was provided to the review committee in advance (14 September). Fast time reaction to the main questions prepared by the reviewers (<24h) We would like to congratulate the AFP team for the enormous amount of work they have put in to the presentations given over the last few days and the progress they are making. We were impressed by the enthusiasm and momentum of the proponents.

This is a very technologically challenging project which requires a lot of careful engineering effort. Significant progress has been made but there is still an enormous amount to do and numerous issues to be resolved. This work will take considerable additional engineering resources from both ATLAS -TC and the LHC. These have been identified but funding and posts need to be released for this work to start. We considered the risks to be extremely significant if they are not released. The timeline for installation is very aggressive given that the HBP needs to be installed by April Failure to meet this deadline would mean a 12 months slippage. Hamburg beam pipe (HBP):

Hamburg beam pipe design (HBP) (2) It is crucial to maintain a close cooperation with several machine experts, in particular the fields of : "impedance” (wake field effects), machine protection, the optics/aperture and vacuum. A dynamic interaction between the detector designers, the beam pipe designers and the wake field experts is strongly encouraged. Each should challenge the other's design in order to facilitate solutions to their own problems. Such interaction has started on the wake field subjects and should be intensified, since the wake field heat dissipation seems to have a major impact on the current design It is our understanding that all the aspects of the HPB will require an LHC review before been accepted by the machine, including interlock strategy and implementation. Interference between the collimator system (TCL5 + not yet existing TCL6) and the experiment must be carefully addressed (background issues and mechanical or installation interferences, including radioactivation). We consider the robust calculation of the background rates to be essential and therefore encourage much closer collaboration with the LHC Fluka experts.

Silicon tracker : We cannot see any show stoppers. We believe they have and will continue to make good use of the developments in other areas of ATLAS especially the IBL. We urge the AFP team to continue the fine start and address the issues raised by the proponents themselves and the review team.

Timing system – We believe the team are making great progress in both the mechanics and electronics and reaching the design goal of <20ps resolution seems achievable between now and the start of their physics program. – We were a little concerned about the transition from phase-0 operation to phase-1 and would like to see the strategy fleshed out in the coming months that would identify a single solution of the lifetime of the physics program. The proponents are themselves mindful of this and we would urge them to continue to explore this area. – In particular we would urge them to continue to explore an evolution of the current proposal (phase-0) which could also satisfy the requirements of the higher luminosity operation in Phase-1 in the context of optimizing the physics return.

General comments We were satisfied that the technical approach of the AFP team as presented does not restrict in any way the core ATLAS physics program. We would urge them to be mindful of the restrictions that will be placed on their program by the evolving radiation environment in the LHC tunnel in the region they plan to work. In particular we were concerned about the frequent replacement of the PMTs for the timing system. We would like to see a detailed timetable and resource plan for the remainder of the project. We would like to understand that sufficient resources will be available for all areas of the detector development, construction, installation and operation. We would also like to understand the risks to the project if any of the significant funding sources are not realized. We encourage the AFP team to explore synergies amongst the various cooling challenges (beam pipe, silicon, …) they will face in the coming years. We ask to have a fallback scenario in which the AFP system progress is de- correlated from the beam pipe installation in the time frame A more complete set of questions (with already some answers) are available in the links: – –

Recommendations We believe that the AFP team has presented technical proposals that are fitting with the physics objectives There are significant technical challenges ahead but we feel that they could all be overcome with the appropriate level of technical support and resources. Our conclusions are based on what the proponents have presented and their working assumptions. Many of these require careful checking in the coming months. On this basis we recommend moving the project to the next phase (TDR writing and submission) In view of the very critical schedule we also recommend the AFP community to investigate a back-up scenario which installs all the required infrastructure by the end of 2014, allowing sequential installation of HBP and detectors in the successive winter shutdowns (and start a physics program a bit later).