LHCf: il run con ioni (e i due nuovi risultati…) Oscar Adriani 3 Aprile 2012

Some historical remarks  LHCf expression of interest for proton/Lead 2012 run  Presentation at the LPCC meeting on October 17 th, 2011  Contact with Atlas management  Letter of Intent submitted to LHCC on December 4 th, 2011  CERN-LHCC /LHCC-I /12/2011  Approved by LHCC in December 2011!  The Committee has independently verified the support of the ATLAS Collaboration, and recommends the acceptance of the Letter of Intent.  And formal approval by RB practically obtained in March 2012!  The plan for LHCf to run during proton-Pb run was agreed by the LHCC and endorsed by the Research Board

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

 We are simulating protons with energy E p = 3.5 TeV  Energy per nucleon for ion is   “Arm2” geometry considered on both sides of IP1 to study both p-remnant side and Pb-remnant side  No detector response introduced yet (only geometrical considerations and energy smearing)  Results are shown for DPMJET and EPOS 1.99, 10 7 events each 140 m p-beamPb-beam “Pb-remnant side” “p-remnant side” What LHCf can measure in the p+Pb run (1) E, p T,  spectra of neutral particles

Proton-remnant side - multiplicity n  Small tower Big tower

Proton-remnant side – photon spectrum Small tower Big tower

Proton-remnant side – neutron spectrum Small tower Big tower 35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS

Proton remnant side – Invariant cross section for isolated  -rays

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)

Proton-remnant side –  0 We can detect  0 ! Important tool for energy scale And also for models check…..

Lead-remnant side – multiplicity Please remind that EPOS does not consider Fermi motion and Nuclear Fragmentation n  Small tower Big tower

Some estimations based on reasonable machine parameters….  Considering machine/physics parameters:  Number of bunches, n = 590 (150 ns spacing)  Luminosity up to cm -2 s -1  Interaction cross section 2 barn  PILE-UP effect  Around 3  interactions per bunch crossing  1% probability for one interaction in 500 ns (typical time for the development of signals from LHCf scintillators after 200 m cables from TAN to USA15)  Some not interacting bunches required for beam-gas subtraction  Beam gas first estimation indicate no problem  Beam Gas/Beam Beam =

 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

Once we have been approved….  We have to do the run!!!!!  Technical points:  Installation issues  Manpower for Installation, setup and data taking  Please note that Arm2 is ‘more italian than japanese’….  Money for missions (Sblocco SJ, see referee presentation) 4days slot to install >3 weeks of run

Preparation for 2012 p-Pb run  We have installed multi-pole connectors in tunnel (02/12)  We have checked that optical fibers are ok (not damaged by radiation) (02/12)  We are producing a new transportation frame for Arm2+electronics  1-2 experts will stay at CERN from September for DAQ commissioning  One month of 24 hours per day shifts (minimum 8 persons at Cern for one month, few from Japan and few from Italy)  Big manpower is requested….  Please note that Atlas ZDC have already been removed in February 2012, since new detectors are being produced. The hadronic part will be installed behind LHCf on Arm2 side, and em+had part on the other side  Sinergies between LHCf and Atlas are encouraged by LHCC  We are working on it Arm2 Pb p IP8 IP2 IP1 Arm2

16 New configuration  Fixing the three sub-systems together New base plate Lead block for balance

A fast spot on 2 new analyses

Submitted to PLB Measured 900 GeV single  spectrum

Type-I Type-II Type-I Type-II E  0 (GeV) PT  0 (GeV/c)  M =3.7% LHCf 7TeV  0 analysis

20 Combined type-I  0 p T spectra (invariant cross section) DPMJET 3.04 QGSJETII-03 SIBYLL 2.1 EPOS 1.99 PYTHIA Sys+stat PT  0 (GeV/c) /N int Ed 3 N/dp <y< <y< <y< <y< <y< <y<11.0

Recent Publication ( ) Titlejournal Monte Carlo study of forward pi0 production spectra to be measured by the LHCf experiment for the purpose of benchmarking hadron interaction models at 10(17)-eV. Astropart.Phys. 34 (2011) 513 Measurement of zero degree single photon energy spectra for s √ = 7- TeV proton-proton collisions at LHC. Phys.Lett. B703 (2011) 128 Study of radiation hardness of Gd(2)SiO(5) scintillator for heavy ion beam (Japan only) JINST 6 (2011) T09004 Luminosity determination in s**(1/2) = 7-TeV proton collisions using the LHCf front counter at LHC. JINST 7 (2012) T01003 Calibration of LHCf Calorimeters for Photon Measurement by CERN SPS Test Beam NIM. A671 (2012)129 Measurement of zero degree photon energy spectra for √s = 900GeV proton-proton collisions at LHC Submitted to PLB Measurement of transverse momentum spectra of forward neutral pions for root s=7TeV proton-proton collisions at LHC To be submitted LHCf detector performance during the LHC runIn preparation

On-going analysis activity and plan  On going activity  7TeV hadron energy spectra  Inelasticity  Italian main analysis task for the near future  Full analysis of single  (larger , p T, invariant cross section)  Full analysis of  0 (Type-II  0 )  Feed back to the models and air shower experiments  Future plans  Strange particles (    0 n, Ks  2  0 (4  ))

Spares slides

Combined type-I  0 p T spectra

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 )

Photons on the proton remnant side  Photon energy distrib. in different  intervals at  s NN = 7 TeV  Comparison of p-p / p-N / p-Pb  Enhancement of suppression for heavier nuclei case QGSJET II-04SIBYLL 2.1 p-p p-N p-Pb All  s 8.81<  <8.99  >10.94 Courtesy of S. Ostapchenko

Lead-remnant side – neutron spectrum Small tower Big tower 35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS

GSO property (EJ260: plastic scintillator used in the current LHCf detectors) GSOEJ-260 density(g/cm3) r.l.(cm) decay time(ns) Fluorescence(NaI=1 00) λem(nm) tolerance(Gy) melting point( ℃ ) 1950 ー Fast among inorganic scintillators Best in the known scintillators Identical to the current scintillators Similar to the current scintillators Heavy; reason to reduce 3->1mm Light collection may differ

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

New structure GSO bar bundle and quartz fiber light guide GSO plate and light guide packed in a new holder GSO plates and bars as calorimeters, but without Tungsten absorber layers

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

Estimation of Beam Gas background  Input from p-p collisions (Data set used for the photon paper).  Luminosity per bunch (L/n) : 2x10 28 cm -2 s -1 /bunch  Intensity per bunch (I/n) : 2x10 10 protons/bunch  Total detected events in 25mm tower at non-bunch crossing : 101 photon events (for non crossing bunches)  DAQ live time : ~ 8x10 3 sec  -> Event rate of beam gas per bunch = 101/8000/3 = Hz  Inputs from p-Pb (assumptions)  Luminosity per bunches (L/n) : 1.7x10 25 cm -2 s -1 /bunch (L=10 28, n=590)  Inelastic cross section : 2 barn  Expected collision rate : 34 Hz  Expected photon detection rate in 25mm : 0.34 Hz (assuming acceptance=0.01)  Estimation of beam-gas background for p-Pb  Assuming as the optics for p-Pb is same as one for p-p (same beta, same emittance), the relative intensity is estimated by using L/n.  (I/n) pPb / (I/n) pp ~ 0.03  The beam-gas background rate should be proportional to the intensity per bunc, so it is estimated as 0.03 x Hz = Hz  As conclusion, the N/S in p-Pb is estimated as / 0.34 = 3x10 -4  Negligible!!!!

Few details about the LHCf Arm2 detector Performances Energy resolution (> 100 GeV): < 3% for 1 TeV photons and  30% for neutrons Position resolution for photons:  40μm (Arm#2) Sampling and imaging E.M. calorimeter  Absorber: W (44 r.l, 1.55λ I )  Energy measurement: plastic scintillator tiles  4 tracking layers for imaging: XY-Silicon strip(Arm#2)  Each detector has two calorimeter towers, which allow to reconstruct  0 Front Counters thin scintillators 80x80 mm 2 monitoring of beam condition Van der Meer scan 25mm 32mm Arm2

LHCf physics program for p-Pb run Important information for the study of the interaction of UHECR in the Earth atmosphere  Comparison with hadronic interaction models  Study of the Nuclear Modification Factor  Inelasticity Precise measurement of of E,  and p T distributions for pseudo-rapidity  > 8.4 both for p and Pb remnant  Single   Neutral pions  Neutrons WHY HOW

Lead-remnant side – photon spectrum Small tower Big tower

LHCf plans for the p/Pb run  We will run with only one detector  Arm2 (W/scint. e.m. calorimeter +  -strip silicon)  Only on one side of IP1 (on IP2 side, compatible with the preferred machine setup: Beam1=p, Beam2=Pb)  Minimal interference with Atlas  Installation during the technical shutdown at the end of the p/p 2012 run