+ Latest LHCf physics results Oscar Adriani University of Florence & INFN Firenze ICHEP 2014 Valencia, July 4 th, 2014

+ Physics Motivations Impact on HECR Physics

+ Extensive air shower observation Longitudinal distribution Lateral distribution Arrival direction Astrophysical parameters Spectrum Composition Source distribution Air shower development HECRs X max is the depth of air shower maximum in the atmosphere. An indicator of CR composition. Uncertainty of hadron interaction models Uncertainty in the interpretation of High Energy Cosmic Rays O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ ④ secondary interactions nucleon,  ① Inelastic cross section If large  rapid development If small  deep penetrating ② Forward energy spectrum If softer shallow development If harder deep penetrating If large k (  0 s carry more energy) rapid development If small k (baryons carry more energy) deep penetrating How accelerator experiments can contribute? ③ Inelasticity k=1-E lead /E avail O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Models tuning after the first LHC data X max as function of E and particle type O. Adriani Latest LHCf physics results Valencia, July 4th, 2014 Significant reduction of differences btw different hadronic interaction models!!!

+ LHC The experimental set-up

+ 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 Energy resolution: < 5% for photons 30% for neutrons Position resolution: < 200 μ m (Arm#1) 40 μ m (Arm#2) Pseudo-rapidity range: η > zero Xing angle η > 140urad O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ LHCf ‘analysis matrix’ O. Adriani Latest LHCf physics results Valencia, July 4th, 2014 Proton equivalent energy in the LAB (eV)  Neutrons 00 SPS Test beam NIM A, 671, 129 (2012) JINST 9 P03016 (2014) p-p 900 GeV4.3x10 14 Phys. Lett. B 715, 298 (2012) p-p 7 TeV 2.6x10 16 Phys. Lett. B 703, 128 (2011) In preparation Phys. Rev. D 86, (2012) p-p 2.76 TeV 4.1x10 15 Phys. Rev. C 89, (2014) p-Pb 5.02 TeV 1.3x10 16 p-p 7 TeV 9.0x10 16 Waiting for LHC restart!

+ Latest analysis Neutrons in 7 TeV pp collisions  0 in 5.02 TeV p-Pb collisions

+ The challenge of neutron analysis O. Adriani Latest LHCf physics results Valencia, July 4th, 2014 Performance for 1.5 TeV neutrons:  E/E ~35%-40%  x ~ 1mm And…. Detector performance is also interaction model dependent! Unfolding is essential to extract physics results from the measured spectra Physics measurement important to try to solve the ‘Muon eccess’ observed from the ground based HECR experiments

+ Inclusive neutron spectra (7 TeV pp) Before unfolding After unfolding Very large high energy peak in the  >10.76 (predicted only by QGSJET)  Small inelasticity in the very forward region! O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ 3.5cm, 4.0cm The 2013 p-Pb run at  s NN = 5.02 TeV  2013 Jan-Feb for p-Pb/Pb-p collisions Installation of the only Arm2 at one side (silicon tracker good for multiplicity) Data both at p-side (20Jan-1Feb) and Pb- side (1fill, 4Feb), thanks to the swap of the beams  Details of beams and DAQ – L = 1x10 29 – 0.5x10 29 cm -2 s -1 – ~ events –  * = 0.8 m, 290  rad crossing angle – 338p+338Pb bunches (min.  T = 200 ns), 296 colliding at IP1 – kHz trig rate downscaled to approximately 700 Hz – Hz ATLAS common trig. Coincidence successful! – p-p collisions at 2.76 TeV have also been taken p Pb IP8 IP2 IP1 Arm2 O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ proton impact parameter : b protonPb Central collisions (Soft) QCD : central and peripheral collisions Ultra peripheral collisions : virtual photons from rel. Pb collides a proton Dominant channel to forward  0 is About half of the observed  0 originate from UPC About half is from soft-QCD Need to subtract UPC component Break down of UPC Comparison with soft- QCD pPb 5.02 TeV:  0 analysis Peripheral collisions O. Adriani Latest LHCf physics results Valencia, July 4th, 2014 Estimation of momentum distribution of the UPC induced secondary particles (Lab frame+Boost): 1. energy distribution of virtual photons is estimated by the Weizsacker Williams approximation 2. photon-proton collisions are simulated by the SOPHIA model (E γ > pion threshold)

+  0 event reconstruction in p-Pb collisions travel in beam pipe (140m) 1. Search for two photons2. BG subtraction by sideband 4. Subtraction of the UPC component LHCf data UPC MC (x0.5) 3. Unfolding the smeared p T spectra and correction for geometrical inefficiency π 0 detection efficiency p-Pb √s=5.02TeV O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Inclusive  0 p T spectra in p-Pb at 5.02 TeV LHCf data in p-Pb (filled circles) show good agreement with DPMJET and EPOS. LHCf spectra in p-Pb are clearly harder than the LHCf data in p-p at 5.02 TeV (shaded area, spectra multiplied by 5). The latter is interpolated from the results at 2.76 TeV and 7 TeV. O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Nuclear modification factor in p-Pb at 5.02 TeV Both LHCf and MCs show strong suppression. NMF grows with increasing p T, as can be expected by the p T spectrum that is softer in p-p 5 TeV than in p-Pb 5 TeV collisions O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Conclusions Very forward  0 production in p-Pb collision has been measured by LHCf Soft-QCD component of the measured  0 production overall agrees with DPMJET 3.04 and EPOS Strong suppression of  0 production is found in p-Pb collision which is consistent with predictions of DPMJET, EPOS and QGSJET II-03 Large amount of high energy neutrons exists in very forward region of p-p collisions, leading to small inelasticity Detector setup for future runs is ongoing smoothly: TeV in GeV polarized p-p RHIC run in 2016 has been proposed to RHIC PAC. We are waiting for official answer O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Backup slides O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ O.Adriani a,b, L.Bonechi b, E.Berti a,b, M.Bongi a,b, G.Castellini c,b, R.D’Alessandro a,b, M.Del Prete a,b,M.Haguenauer e, Y.Itow f,g, K.Kasahara h, K. Kawade g, Y.Makino g, K.Masuda g, Y.Matsubara g, E.Matsubayashi g, H.Menjo i, G.Mitsuka g, Y.Muraki g, P.Papini b, A.- L.Perrot j, D.Pfeiffer j, S.Ricciarini c,b, T.Sako g, Y.Shimitsu h, Y.Sugiura g, T.Suzuki h, T.Tamura k, A.Tiberio a,b, S.Torii h, A.Tricomi l,m, W.C.Turner n, K.Yoshida o, Q.Zhou g a)University of Florence, Italy b)INFN Section of Florence, Italy c)IFAC-CNR, Florence, Italy d)IFIC, Centro Mixto CSIC-UVEG, Spain e)Ecole Polytechnique, Palaiseau, France f)KMI, Nagoya University, Nagoya, Japan g)STELAB, Nagoya University, Japan h)RISE, Waseda University, Japan i) School of Science, Nagoya University, Japan j)CERN, Switzerland k)Kanagawa University, Japan l)University of Catania, Italy m)INFN Section of Catania, Italy n)LBNL, Berkeley, California, USA o)Shibaura Institute of Technology, Japan The LHCf Collaboration O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ UPC subtraction O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Muon excess at Pierre Auger Obs. Pierre Auger Collaboration, ICRC 2011 (arXiv: ) Pierog and Werner, PRL 101 (2008) Auger hybrid analysis event-by-event MC selection to fit FD data (top-left) comparison with SD data vs MC (top- right) muon excess in data even for Fe primary MC EPOS predicts more muon due to larger baryon production => importance of baryon measurement O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Derivation of  0 p T spectra in p-p at 5.02 TeV 1. Thermodynamics (Hagedorn model) 2. Gauss distribution The p T spectra in “ p-p at 5.02TeV ” are obtained by the Gauss distribution with the above and absolute normalization. 22 O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ The importance of neutrons in the very forward region Motivations: Inelasticity measurement: k=1-p leading /p beam Muon excess at Pierre Auger Observatory c osmic rays experiment measure HECR energy from muon number at ground and florescence light % more muons than expected have been observed Number of muons depends on the energy fraction of produced hadron Muon excess in data even for Fe primary MC EPOS predicts more muon due to larger baryon production R. Engel importance of baryon measurement O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ PRELIMINARY p-Pb run:  0 O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Comparison wrt MC Models at 7 TeV DPMJET 3.04 SIBYLL 2.1 EPOS 1.99 PYTHIA QGSJET II-03 Gray hatch : Systematic Errors Magenta hatch: MC Statistical errors O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ DATA vs MC : comp. 900GeV/7TeV 900GeV 7TeV η > < η <8.9 None of the model nicely agrees with the LHCF data Here we plot the ratio MC/Data for the various models > Factor 2 difference O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ DATA : 900GeV vs 7TeV 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) 900GeV vs. 7TeV with the same PT region 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 small- η Coverage of 900GeV and 7TeV results in Feynman-X and P T Good agreement of X F spectrum shape between 900 GeV and 7 TeV.  weak dependence of on E CMS O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+  0 P T spectra for various y bin: MC/data EPOS gives the best agreement both for shape and yield. DPMJET 3.04 QGSJETII-03 SIBYLL 2.1 EPOS 1.99 PYTHIA P T [GeV] 00.6P T [GeV] 00.6P T [GeV] 00.6P T [GeV] 00.6P T [GeV] 00.6P T [GeV] MC/Data O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+  0 Data vs MC at 7 TeV cm O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+  0 analysis at √s=7TeV 1. Thermodynamics (Hagedron, Riv. Nuovo Cim. 6:10, 1 (1983)) 2. Numerical integration actually up to the upper bound of histogram Systematic uncertainty of LHCf data is 5%. Compared with the UA7 data (√s=630GeV) and MC simulations (QGSJET, SIBYLL, EPOS). Two experimental data mostly appear to lie along a common curve → no evident dependence of on E CMS. Smallest dependence on E CMS is found in EPOS and it is consistent with LHCf and UA7. Large E CMS dependence is found in SIBYLL Systematic uncertainty of LHCf data is 5%. Compared with the UA7 data (√s=630GeV) and MC simulations (QGSJET, SIBYLL, EPOS). Two experimental data mostly appear to lie along a common curve → no evident dependence of on E CMS. Smallest dependence on E CMS is found in EPOS and it is consistent with LHCf and UA7. Large E CMS dependence is found in SIBYLL PLB (1990) y lab = y beam - y Submitted to PRD (arXiv: ). p T spectra vs best-fit function Average p T vs y lab Y Beam =6.5 for SPS Y Beam =8.92 for7 TeV LHC O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Determination of energy from total energy release PID from shape Determination of the impact point Measurement of the opening angle of gamma pairs Identification of multiple hit 25mm Tower32mm Tower  600GeV photon  420GeV photon Longitudinal development measured by scintillator layers Transverse profile measured by silicon  –strip layers ` X-view Y-view ` Reconstruction of  0 mass: A very clear  0 in Arm2 O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ p-p at 13TeV (2015) Main target: measurement at the LHC design energy. Study of energy scaling by comparison with √s = 900 GeV and 7 TeV data Upgrade of the detectors for radiation hardness. p-light ions (O, N) at the LHC (2019?) It allows studying HECR collisions with atmospheric nuclei. RHICf experiment at RHIC Lower collision energy, ion collisions. LOI to the RHIC committee submitted p-p collisions: Max. √s = 500 GeV Polarized beams Ion collisions: Au-Au, d-Au Max. √s = 200 GeV Possible, d-O,N (p- O,N)  Cosmic ray – knee energy. 10c m LHCf: future plan O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Physics of RHICf Energy Scaling of Very Forward at p-p √s=500GeV Measurement at p-light ion collisions (p-O) √s NN =200GeV Asymmetry of Forward Neutron with polarized beams LOI submitted to the RHIC committee and nicely appreciated More news soon Physics of RHICf Y. Fukao et al.,PLB 650 (2007) The STAR Collaboration, PRL 97 (2006) Nuclear modification factor at d-Au 200GeV O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ η ∞ 8.5 What LHCf can measure Energy spectra and Transverse momentum distribution of Energy Low multiplicity !! High energy flux !! simulated by DPMJET3 Gamma-rays (E>100GeV,dE/E<5%) Neutral Hadrons (E>a few 100 GeV, dE/E~30%) π 0 (E>600GeV, dE/E<3%) at pseudo-rapidity range >8.4 Front view of 100 μ rad crossing angle beam pipe shadow O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ Common trigger with ATLAS LHCf forced to trigger ATLAS Impact parameter may be determined by ATLAS Identification of forward-only events MC impact parameter vs. # of particles in ATLAS LUCID O. Adriani Latest LHCf physics results Valencia, July 4th, 2014

+ L 90% L 20% Layer[r.l.] hadron photon projection along the sloped line L 90% L 20% Shower development in the small calorimeter tower Neutron identification Particle Identification with high efficiency and small contamination is necessary A 2D method based on longitudinal shower development is used L 20% (L 90% ): depth in X 0 where 20% (90%) of the deposited energy is contained L 2D =L 90% L 20% Mean purity in the 0-10 TeV range: 95% Mean efficiency: ~90% L 2D O. Adriani Latest LHCf physics results Valencia, July 4th, 2014