 Based on 2+2 Roman Pot Stations on each side of ATLAS at ~ 240 m from the Interaction Point  Aim in Run 2 at measuring the total cross section and absolute luminosity at full LHC energy  The measurement is based on elastically scattered particles at very small angles and for the ultimate performance it requires a very high  * optics (~2.6 km)  But this needs the installation of water cooled cables scheduled to be installed in 2015 winter stop or earlier if possible  In the meanwhile the measurement, with lower precision, can be done OR knowing the optics to extreme details (difficult) AND/OR by using the local angle measurement (one of the ECRs) 2 ALFA Detector B. Di Girolamo – LSC Meeting - 16 August 2013

 The ATLAS ALFA Detector prepared two ECRs  LHC-XRP-EC-0008: Upgrade of the ATLAS/ALFA Roman Pots  Concerning impedance improvements to contrast the heating from wake field and limitations imposed to LHC  Circulated and approved after the requested modifications  LHC-XRP-something: Moving ATLAS/ALFA RP Stations  Being put om EDMS for circulation 3 Two ECRs B. Di Girolamo – LSC Meeting - 16 August 2013

 Starting in 2011 the ALFA detectors have suffered increasing temperature with increasing luminosity  We need to correct this to allow smooth LHC operations at higher luminosity after LS1 and the survival of the detector  This ECR illustrates the measures to upgrade the Roman Pots to minimize impedance (always good) and therefore the heating of the Pots that would induce damages to the (not cooled) scintillating fibre detectors 4 LHC-XRP-EC-0008 B. Di Girolamo – LSC Meeting - 16 August 2013

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9 UPDATE: Tests done with very good results

 Additional measures are being implemented with heat spreaders inside the Pots and provisions for possible extrenal cooling if all measures won’t be enough (and if LHC outperforms) 10 Additional measures B. Di Girolamo – LSC Meeting - 16 August 2013

 The document is in approved state in EDMS  A second version with all comments responses is being uploaded  Main risks  Schedule: pointed out by Katy and addressed  Not readiness and catastrophic scenario pointed out by Beniamino: replacement chambers with supports are in hand  Other mitigations: a spare vacuum chamber has been ordered in case of issues; An external cooling system is being investigated if the simulations and the lab measurement would have been too optimistic  All the stations are in lab, being reworked and they have a precise rendez-vous with TE/VSC to be requalified prior to re-installation 11 Status B. Di Girolamo – LSC Meeting - 16 August 2013

12B. Di Girolamo – LSC Meeting - 16 August 2013

 Second ECR on station move  As said earlier, without the special water cooled cables the measurement is complicated  Improvement to precision can come from a better measurement of the scattering angle locally  That entails that if stations can be moved apart the angle is better measured with the increased lever arm  Status: being put in the system now  Opinion: the first idea was too complicated, then thanks to all EN and TE help it became a feasible one 13 LHC-XRP-something B. Di Girolamo – LSC Meeting - 16 August 2013

14B. Di Girolamo – LSC Meeting - 16 August 2013

15B. Di Girolamo – LSC Meeting - 16 August 2013

 The solution has been deeply analysed and reviewed by LTEX  The best would be to have the water cooled cable installed, this is a mitigation to the lack of these cables  It doesn’t cost much and it has a verified low impact (but let’s see the results of the ECR circulation)  In very simple words, the distance between the stations is doubled and the benefit on the precision is a factor ~2.  Impact:  Connection between DQRs need to be shortened: extension were installed exactly to accommodate ALFA, now they only need to be removed. Simple (Knud D-P) 16 Status and impacts B. Di Girolamo – LSC Meeting - 16 August 2013

 Impacts:  The DJRQD box needs to go on top of DQR3, as done in RR17: we have been told it is simple (Knud D-P)  Rearrengement of beam pipes: no new pipes needed, got ensured it is simple (Mark G)  New positions needed for floor mounted cable box, owner TE- CRG. 20 kCHF for both sides (Knud D-P)  No clearance problems vs QRLs  Extension (4 meters) of the ALFA cables done by ATLAS/ALFA resources  Schedule: same contraints as first ECR  Catastrophic scenario: replacement chambers in hands if stations not ready, but that is indipendent of this ECR 17 Impacts cont. B. Di Girolamo – LSC Meeting - 16 August 2013

 The ALFA upgrade ECR is in approved state and I pushed to get the second version addressing all the comments: it will be in EDMS next week  The ALFA stations move ECR is mature on paper and it needs to go through the circulation 18 Concluding B. Di Girolamo – LSC Meeting - 16 August 2013