1. AFP Introduction September 10th 2014 M. Bruschi, INFN Bologna (Italy) 1

2. ALFA and AFP Detectors t=-p T 2 and  =  E/E 0 In diffraction, coherent interaction of proton is soft  p T ~ 1 GeV Elastic scattering:  = 0  diffraction:  <0.2 September 10th 2014 M. Bruschi, INFN Bologna (Italy) 2 MAD-X + MC generator-level

3. Very low luminosity September 10th 2014 M. Bruschi, INFN Bologna (Italy) 3 ATLAS and CMS agree within systematic uncertainties (hadron |  <4.7 vs. |  <4.9: 5% Diff. model for unfolding: 10%) 1)CMS sytematically above ATLAS 2)Pythia8 predicts SD~DD Proton tagging could shed light on 1) and 2) More generally, the possibility to tag diffractive protons with AFP will improve the quality of the interpretation Underlying event MPI All the other soft QCD measurements performed using only the central detector

4. And a Low/Medium luminosity September 10th 2014 M. Bruschi, INFN Bologna (Italy) 4 S “Standalone” MC simulations

5. High lumi program QUARTIC Gauge Couplings – testing BSM models Reaching limits predicted by string theory and grand unification models (10 - 14 -10 -13 for  ) Exc. Jets – verification of QCD production models, unintegrated gluon PDFs Program will be discussed in ATLAS when data on beam background available  requires moderate timing, the other final states ≤ 10 ps September 10th 2014 M. Bruschi, INFN Bologna (Italy) 5 Exclusive Jets γ γ

6. First Integrated AFP Prototype September 10th 2014 M. Bruschi, INFN Bologna (Italy) 6

7. The AFP Testbeam Team September 10th 2014 M. Bruschi, INFN Bologna (Italy) 7

8. Tracking-Timing Correlations (Preliminary Analysis) September 10th 2014 M. Bruschi, INFN Bologna (Italy) 8

9. Time resolution between LQbars (Preliminary Analysis) September 10th 2014 M. Bruschi, INFN Bologna (Italy) 9 Oscilloscope Measurement HV=1900 V

10. Conclusions AFP will give ATLAS the possibility to complete and enhance the forward physics program initiated by ALFA ALFA and AFP have complementary characteristics for high  * running AFP has unique characteristics for low  * running and will allow to exploit an interesting QCD program at low- , and an exciting program at high- , if the beam background conditions will allow the latter The detector, including its beam interface, will be built using very advanced and solid technology A prototype of the full detector (tracking+timing) has been recently tested on beam successfully proving the integration of the two parts in a common TDAQ scheme The group has proven motivation and skill in the last years and the collaboration with ALFA is now well grounded September 10th 2014 M. Bruschi, INFN Bologna (Italy) 10

11. Backup September 10th 2014 M. Bruschi, INFN Bologna (Italy) 11

12. ATLAS and its Forward Detectors Example of ATLAS measurement Rapidity gap cross sections ALFA elastic d  /dt and  tot at sqrt(s) = 7 TeV September 10th 2014 M. Bruschi, INFN Bologna (Italy) 12 AFP LUCID p-p @14 TeV (DPMJET)

13. Running Scenario at low-  September 10th 2014 M. Bruschi, INFN Bologna (Italy) 13 Program approved by ATLAS (pending resources) No or loose (~50 ps) timing needed from AFP

14. Importance of ToF Significance >100 for 0.1<  <1 also with no ToF Factor 10 pile-up reduction in AFP for  ~50 for ToF with  t~10 ps Conclusion: High performance ToF needed mainly for the high-lumi program (and not for the approved program in RUN2) AFP trigger is instead needed for RUN2: but in this case also a system based on scintillators or Silicon/Diamond will be sufficient to fully exploit the approved program September 10th 2014 M. Bruschi, INFN Bologna (Italy) 14 0.3 0.02

15. AFP Full Simulation September 10th 2014 M. Bruschi, INFN Bologna (Italy) 15

16. Full Simulation results September 10th 2014 M. Bruschi, INFN Bologna (Italy) 16

17. AFP Detector System Performance Results from full simulation of AFP detectors and the whole forward region Mild degradation of performance due to pile-up Detector capable of running in pile-up conditions  acceptance in the range 1.5%-15% September 10th 2014 M. Bruschi, INFN Bologna (Italy) 17

18. Classification of diffractive events Diffractive and elastic events: ~ 40% of LHC pp collisions Traditional measurements use rapidity gap method to separate contributions of inelastic non diffractive production ATLAS has |  |<4.9 coverage which doesn’t work for “too” small (order of 10 GeV) M x =sqrt(s  ) of diffractive system because  =-log(  ) The Indirect measurement of  via energy seen in calorimeter is not very precise due to invisible energy and it works only in a limited region of  No measurement of t Proton tagging is the only way for a more detailed probing of diffraction September 10th 2014 M. Bruschi, INFN Bologna (Italy) 18

19. Diffractive processes at ATLAS Forward rapidity gaps defined as larger  F region on detector edge (  =±4.9) devoid of p T >200 MeV particles Measured d  /  F ~ 1 mb for  F > 3 Default PHOJET and PYTHIA do not describe the rise of the cross section observed at  F > 5 Rise interpreted from a triple Pomeron contribution with a Pomeron intercept  P (0) > 1 Slope very sensitive to the precise value of  P (0) September 10th 2014 M. Bruschi, INFN Bologna (Italy) 19 Eur. Phys. J. C72 (2012) 1926

20. The AFP detectors September 10th 2014 M. Bruschi, INFN Bologna (Italy) 20 Purpose:Tag and measure diffractive protons at 210 m (two arms) providing , t Precision MASS SPECTROMETER. In case of exclusive production (Double Tag) M= sqrt(  1  2 s) Detectors (in 2+2 Horizontal RP) Radiation hard “edgeless” 3D Silicon detectors with ~  rad angular resolution for proton tracks reconstruction (204m,212m) High performing timing detectors (212m) (~ 10ps resolution, for proton pile-up background rejection at high mu) 0.3 0.02 Horizontal RP

21. AFP Detector System September 10th 2014 M. Bruschi, INFN Bologna (Italy) 21 Tracking +Timing in one RP

22. September 10th 2014 M. Bruschi, INFN Bologna (Italy) 22

23. September 10th 2014 M. Bruschi, INFN Bologna (Italy) 23