LHCf Status Oscar Adriani University of Florence & INFN Firenze On behalf of the LHCf Collaboration June 13 th, 2012

Introduction and contents  LHCf status after march 2012 LHCC   0 paper submitted to PRD  Selected final results will be shown  Short spot on neutron analysis  Arm1 upgrade for 2014 run under way  Preparation for p/Pb autumn run O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

LHCf: location and detector layout 44X 0, 1.6 int INTERACTION POINT IP1 (ATLAS) Detector II TungstenScintillator Silicon  strips Detector I TungstenScintillator Scintillating fibers 140 m n π0π0 γ γ 8 cm6 cm Front Counter Arm#1 Detector 20mmx20mm+40mmx40mm 4 X-Y SciFi tracking layers Arm#2 Detector 25mmx25mm+32mmx32mm 4 X-Y Silicon strip tracking layers O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

π 0 analysis: P T spectra for different rapidity bins Submitted to PRD CERN-PH-EP

Type-I Type-II Type-II at small tower Type-II at large tower Type-I LHCf-Arm1 Type-II LHCf-Arm1 LHCf-Arm1 Data 2010 BG Signal Preliminary Large angle Simple Clean High-stat. Small angle large BG Low-stat., but can cover High-E Large-P T π 0 analysis at √s=7TeV Submitted to PRD (arXiv: ). O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Type I π 0 analysis procedure Mass, energy and transverse momentum are reconstructed from the energies and impact positions of photon pairs measured by each calorimeter Analysis Procedure Standard photon reconstruction Event selection - one photon in each calorimeter - reconstructed invariant mass Background subtraction by using outer region of mass peak Unfolding for detector response. Acceptance correction. Dedicated part for π 0 analysis I.P.1   1 (E 1 )  2 (E 2 ) 140m R O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Acceptance for π 0 at LHCf-Arm1 Validity check of unfolding method Remaining background spectrum is estimated using the sideband information, then the BG spectrum is subtracted from the spectrum obtained in the signal window. Raw distributions are corrected for detector responses by an unfolding process that is based on the iterative Bayesian method. (G. D ’ Agostini NIM A 362 (1995) 487) Detector response corrected spectrum is then corrected for acceptance LHCf-Arm1 √s=7TeV 9.0<y<11.0 True EPOS Unfolded(by π 0 +EPOS) Unfolded(by π 0 +PYTHIA) Measured EPOS Acceptance and unfolding Submitted to PRD (arXiv: ). O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Arm1 vs Arm2 comparison O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

π 0 results: Data vs MC O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

π 0 results: Data/MC Submitted to PRD (arXiv: ). O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Data/MC commented  dpmjet 3.04 & pythia show overall agreement with LHCf data for 9.2<y<9.6 and p T <0.25 GeV/c, while the expected   production rates by both models exceed the LHCf data as p T becomes large  sibyll 2.1 predicts harder pion spectra than data, but the expected   yield is generally small  qgsjet II-03 predicts   spectra softer than LHCf data  epos 1.99 shows the best overall agreement with the LHCf data.  behaves softer in the low p T region, p T < 0.4GeV/c in 9.0<y<9.4 and p T <0.3GeV/c in 9.4<y<9.6  behaves harder in the large p T region. O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Y LAB = Y beam - Y distribution O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012 Two different approaches used to derive the average transverse momentum, p T in different rapidity bins: 1.by fitting an empirical function to the p T spectra in each rapidity range (thermodynamical approach) 2.by simply numerically integrating the p T spectra Results of the two methods are in agreement and are compared with UA7 data and hadronic model predictions. Two UA7 and LHCf experimental data show the same trend → no evident dependence of on E CM S. Y Beam =6.5 for SPS Y Beam =8.92 for7 TeV LHC

small-η = Large tower big-η =Small tower A jump back to  analysis: Comparison btw 900GeV and 7TeV spectra Coverage of the photon spectra in the plane Feynman-X vs P T O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

small-η = Large tower big-η =Small tower A jump back to  analysis: Comparison btw 900GeV and 7TeV spectra Coverage of the photon spectra in the plane Feynman-X vs P T O. Adriani LHCf Status 110th LHCC Meeting, 13th June GeV vs. 7TeV with the same PT region 900 GeV Small+large tower

small-η = Large tower big-η =Small tower A jump back to  analysis: Comparison btw 900GeV and 7TeV spectra Normalized by the number of entries in X F > 0.1 No systematic error is considered in both collision energies. X F spectra : 900GeV data vs. 7TeV data Good agreement of X F spectrum shape between 900 GeV and 7 TeV.  weak dependence of on E CMS Preliminary Data 2010 at √s=900GeV (Normalized by the number of entries in X F > 0.1) Data 2010 at √s=7TeV (η>10.94) Coverage of the photon spectra in the plane Feynman-X vs P T O. Adriani LHCf Status 110th LHCC Meeting, 13th June GeV vs. 7TeV with the same PT region 900 GeV Small+large tower

Neutron (very preliminary…) analysis

Why neutron measurement is important for CR physics Auger hybrid analysis event-by-event MC selection to fit FD data (top plot) comparison with SD data vs MC (bottom plot) Clear muon excess in data even for Fe primary MC The number of muons increases with the increase of the number of baryons! => importance of direct baryon measurement

Neutron Detection Efficiency and energy linearity Efficiency at the offline shower trigger Flat efficiency >500GeV O. Adriani LHCf: results on forward particle production at LHC anf future perspectives Paris, June 11, 2012 % Linear fit Parabolic fit

Energy and Position Resolution O. Adriani LHCf: results on forward particle production at LHC anf future perspectives Paris, June 11, 2012 X Y Neutron incident at (X,Y) = (8.5mm, 11.5mm) ~1mm position resolution Weak dependence on incident energy We are trying to improve the energy resolution by looking at the ‘electromagneticity’ of the event

Status of the LHCf upgrade and re-installation issues for p/Pb 2012 run

LHCf Upgrade for the 14 TeV p-p run  Calorimeter radiation hardening by replacing plastic scintillator with GSO  Scintillator plates  3 mm  1mm thick scintillators  Acrylic  quartz light guides  construction and light yield uniformity test carried out in Japan  SciFi  1 mm square fibers  1 mm GSO square bars  No clad-core structure (GSO bar)  Attenuation and cross talk test carried out  Acrylic light guide fiber  quartz light guide fibers  Construction and light yield test carried out  Production and laboratory tests of the new scintillators in Japan is finished  Beam test at Ion facility (HIMAC) is underway this week  Arm1 will be re-assembled in Florence starting from end of June  Same procedure will be followed in 2013 for the Arm2 detector  Upgrade of the silicon positioning measurement system  Rearranging Silicon layers for independent precise energy measurement  Increase the dynamic range to reduce saturation effects O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Re-installation for the p/Pb run  Arm2 will be re-installed in the TAN during the technical stop foreseen at the end of the p/p run  We have modified the LHCf support structure and cabling to significantly reduce the installation required time  The procedure for reinstallation has been carefully discussed in the LTEX meetings and is ready  Checked with RP  RP gave green light  We will continue discussion with ATLAS for trigger and data exchange, to get the maximum physics outcome for the data, following the LHCC reccomendation O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Conclusions  Three physics papers have been completed:  Inclusive  at 900 GeV  Inclusive  at 7TeV   0 Pt vs y spectra  We are in strict contacts with model developers, and the feedback from our data is important and appreciated in the community  Neutron analysis is ongoing and is our next priority  Upgrade work for 14 TeV almost completed for Arm1  Beam test in August  p/Pb interesting physics case will be investigated by LHCf with Arm2 detector in Autumn O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Spares slides O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Fast install/uninstall Silicon strip FE electronics LHCf main detector Calorimeters amplifier To be assembled in a single structure Now 35 BNC connections in the tunnel To be packed in 2- 3 Harting multipoles connectors Now 3 main structures installed separately O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Radiation hardness of GSO  No decrease up to 1 MGy  +20% increase over 1 kGy (τ=4.2h recovery)  2 kGy is expected for 350nb 14TeV pp) １ kGy Not irradiated ref. sample Irradiated sample τ~4.2h recovery K. Kawade et al., JINST, 6, T09004, 2011 Dose rate=2 kGy/hour (≈10 32 cm -2 s -1 ) O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Uniformity test using C beam at HIMAC (preliminary results from quick analysis) PMT via fiber bundle No particle due to the beam pipe Scan examples for a 20mmx20mm and a 40mmx40mm GSO plates All scintillators of Arm1 were mapped by C beam Similar uniformity to the current detector is obtained mm O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

GSO bars cross talk and attenuation  Attenuation and cross talk are acceptable to determine the position of single particle shower and multihit identification  For multihit analysis, further study is necessary  Paint between the bars reduces cross talk, but worsens attenuation and its bar-to-bar variation No paint between bars -30%/35mm 10% 0% Irradiated bar (100%) Attenuation along the longest 40mm bar Cross talk O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Global LHCf physics program LHCf measurement for p-Pb interactions at 3.5TeV proton energy could be easily and finely integrated in the LHCf global campaign. PeriodType Beam energy LAB proton Energy (eV) Detector 2009p - p GeV Arm1+Arm2 2009/2010p - p TeV Arm1+Arm2 2012p – Pb 3.5 TeV proton E Arm2 2014p - p7+7 TeV10 17 Arm1+Arm2 upgraded O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Proton-remnant side – photon spectrum Small tower Big tower O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Proton-remnant side – neutron spectrum Small tower Big tower 35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Proton remnant side – Invariant cross section for isolated  -rays O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

What LHCf can measure in the p+Pb run (2) Study of the Nuclear Modification Factor Nuclear Modification Factor measured at RHIC (production of  0 ): strong suppression for small p t at =4. LHCf can extend the measurement at higher energy and for  >8.4 Very important for CR Physics Phys. Rev. Lett. 97 (2006) O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Lead-remnant side – multiplicity Please remind that EPOS does not consider Fermi motion and Nuclear Fragmentation n  Small tower Big tower O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

 Minimum required number of collision: N coll = 10 8 (factor 10 more statistics wrt shown plots)  Integrated luminosity L int = 50  b -1  2  10 6 single photons expected on p-remnant side   0 expected on same side  Assuming a pessimistic scenario with luminosity L = cm -2 s -1 :  Minimum running time for physics t = 140 h (6 days) … and required statistics to complete the p/Pb physics run O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012