Pos(ENAS 6)066 , D , Bc , B , H , K

PoS(ENAS 6)066 , d , bc , b , h , K. Taki g http://pos.sissa.it/ , P. Papini g , D. Macina d , T. Suzuki , R. D’Alessandro d bc , M. Nakai d , K. Kawade g , K. Suzuki l g , G. Castellini , Y. Muraki b d , K. Kasahara , Y. Shimizu d f d f , M. Bongi b and W. C. Turner , G. Mitsuka b f ak , Y. Itow e , T. Sako bi , L. Bonechi , H. Menjo bc d , A. Tricomi g , S. Ricciarini , M. Haguenauer h d , S. Torii j , O. Adriani a , K. Masuda ∗ d [email protected] Speaker. LHCf is a collider experiment dedicatedof to cosmic-ray very physics. forward It particles measures generated theerrors in energy in spectrum air-shower pp simulations collisions used in in ultra-high-energyAuger LHC. cosmic-ray Observatory. Its In experiments this like aim paper the we is Pierre briefly summarize toanalyses, the and minimize current works status systematic of for the foreseen experiment: detector DAQ, upgrade. ∗ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c VI European Summer School on ExperimentalSeptember Nuclear 18-27, Astrophysics, 2011 ENAS 6 Acireale Italy K. Fukatsu T. Mase A.-L. Perrot LBNL, Berkeley, California, USA E-mail: K. Noda University of Catania, Italy The LHCf experiment Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan Ecole-Polytechnique, Palaiseau, France Kobayashi-Maskawa Institute for the Origin ofNagoya, Particles Japan and the Universe, Nagoya University, RISE, Waseda University, Japan CERN, Switzerland Centro Siciliano di Fisica Nucleare eKanagawa Struttura University, della Japan Materia, Catania, Italy T. Tamura INFN Section of Catania, Italy INFN Section of Florence, Italy University of Florence, Italy i j l f e c k g h a b d PoS(ENAS 6)066 ]. It 5 K. Noda ]. However, this result is eV in cosmic-ray energy. 1 17 ] in SPS, whose collision energy 4 ]. Furthermore, the depth of the shower maxi- 2 2 eV have been detected on the Earth since several decades eV, called ultra-high-energy cosmic rays (UHECRs), have 15 18 eV in cosmic-ray energy. On the other hand, the LHCf experiment is designed 14 ]. Then, the energy of the cosmic ray is transferred inelastically to secondary particles 3 LHCf is installed at the CERN Large Hadron Collider in Geneva, Switzerland. The LHCf There are several key quantities for the air-shower development. It starts with the first interac- Cosmic rays with energy above 10 If we try to understand the cosmic rays in a step-by-step way from the Earth side, we must corresponds to 10 to obtain data with a collision energy of 14 TeV, corresponding to 10 measures the spectra of very forwardted in neutral high particles energy (photons, collisions neutral in pionshighest LHC. energy and As is neutrons) for that the emit- for spectrum of neutral forward pions pions, by available the data UA7 with experiment the [ Thus, it will be expectedenergy. to reduce the uncertainty of the model dependence close to the UHECR detector is located at 140m awaycollision from angle. Interaction Point The detector 1 is (IP1; installed the in(TAN). ATLAS the Inside site) instrumentation the and slots TAN at of the zero the beam neutral degree vacuum particletube chamber absorbers facing makes the a IP Y-shaped transition to from two a separate single beam beam tubes joining to the arcs of LHC. The TAN instrumentation 2. The LHCf detector tion of the cosmic ray andinteraction a is nucleus of important. the In atmosphere, LHC wheresection the the inelastic [ TOTEM experiment cross section has of already the measuredlike first the baryons inelastic and cross mesons. Thiscles secondary in particles cascade. emitted at Thus, forward thethe angles forward amount particles produce of are more transferred important parti- energy here. (inelasticity) The and latter is the the energy main spectrum goal of of the LHCf experiment [ mum is severely dependent on the hadronicthe interaction air-shower models development. used in The Monte models Carloon simulations are for the based Regge on Field on theory thepart for perturbative only soft QCD in part for phenomenology. but hard Therefore, they part inchemical treat composition, and order the we to non-linear must reduce reduce effects the first for the uncertaintyin soft model in colliders dependence and the like with semi-hard the discussion experimental Large data of Hadron obtained the Collider (LHC). understand first what the cosmicthe maximum rays depth are, of i.e., the air-shower thePierre development Auger chemical is Observatory generally composition. suggests used. that Recently, For the ation chemical its measurement from composition determination, by a of UHECR light has chemical a composition gradual (proton) transi- to a heavy one (iron) [ The LHCf experiment 1. Introduction ago, but there still remain many uncertaintiesproperties in of understanding cosmic of rays their properties. beyondnot In 10 particular, been the clarified yet.mechanism, We do and not thus know the much astrophysicalonly about origin. through their One a chemical reason composition, particle iserrors the cascade caused that propagation called by they the air-shower, can air-shower and development. be that detected indirectly we must always care for systematic different from a result by the HiRes experiment [ PoS(ENAS 6)066 K. Noda ]. 5 ). Each of the two LHCf detectors 1 3 Schematic view of the LHCf detectors (Arm1 on the left, Arm2 on the right). Plastic scintillators The current LHCf detector was not designed to be a radiation hard detector. That is because the The detector can identify photons with the two calorimeters. It measures their energy spectrum The overall concepts for the two Arms are the same (Fig. model discrimination requires just a short periodbefore during the the high early luminosity phase operations. of the For LHC the commissioning LHC operation in 2009 and 2010, we have obtained beyond 100 GeV withposition less resolution. than If 5% a energy photonexpected to resolution, is be detected and reconstructed in their as eachdetector. an incident of event the position from Measured two a with spectrum calorimeters neutral 0.2mm atinteraction of pion. the models. neutral This same Also, is pions time, hadronic the can showers it mainresolution of is be target of high-energy of about used neutrons 30%. the can to be LHCf discriminate measured with among energy the hadronic 3. Data acquisition consists of two smallcalorimeter sampling layers. calorimeters and The fourabsorbers, calorimeter position and is it sensitive has made layers a of insertedWe total call 16 into length the equivalent plastic the to calorimeters scintillators 44 smallamong sandwiched radiation & the lengths, layers by large of and the towers. tungsten 1.55 calorimeters for interaction Thescintillating determining length. fibers the four transverse as position shower the positions. sensitive position-sensitive Arm1 layers, layers utilizes In while are Arm2 addition uses distributed the silicon (Si) geometrical microstrippurposes configurations sensors. of of redundancy and the consistency two check.plastic towers In scintillators front for is of inserted. each each It detector, Armthan a provides are the Front useful calorimeters. Counter trigger different Many made information for additional of by details the covering of a both larger Arms aperture can be found in [ slot is in thebeam crotch separation of dipole the before Y. reaching Chargeddetectors. TAN, secondary This so location particles only covers from the neutral pseudo-rapidity IPslot particles range exists are from are in 8.4 swept each incident to of aside on infinity. both by This the sidesnamed instrumentation of Arm1 LHCf the IP1, and inner thus Arm2. we have two detectors located on opposite sides of IP1, Figure 1: (light blue color) are interleaved withtillating tungsten fibers blocks (dark in gray Arm1, color). dark Fourin blue position each color; sensitive calorimeter. silicon layers micro-strip (scin- detectors in Arm2, purple color) are distributed The LHCf experiment PoS(ENAS 6)066 K. Noda ]. It is ded- 7 Layer 1st Layer 2nd Layer 3rd Layer 4th Layer 1st Layer 2nd Layer 3rd Layer 4th Layer Strip Number Strip Number Large Tower ]. 0 2 4 6 8 10 12 14 16 ] (a candidate for detection of two photons from 0 6 7

500

2500 2000 1500 1000 dE [MeV] dE 4 = 0.9 & 7 TeV. The accumulated numbers of events are X-View Y-View Layer s √ Small Tower , we show an example of a candidate of a neutral pion event, i.e., one photon for each 2 0 50 100 150 200 250 300 350 0 2 4 6 8 10 12 140 16 50 100 150 200 250 300 350 0 0 0

An example of data taken during 2010 operation [ 500 500 500

ADC counts ADC 2500 2000 1500 1000 counts ADC 1000 1000 dE [MeV] dE In Fig. The first physics result from the LHCf experiment has been published in 2011 [ about 100k showers at 0.9neutral pion TeV, events, and for about each of 400Mwere the showers removed two from Arms. at the After 7 slot the TeV, in operation corresponding 2010. for to several months, about the 1M detectors 4. Photon analysis tower, obtained by Arm2. Wetwo can layers see of sharp the peaks Si from microstripof sensors. single the With photon photon the events pairs. information detected we It by can isused the reconstruct expected for the first to invariant an be mass around energy the calibration.both mass of of We the the have neutral Arms. also pion A obtained (135 preliminary the MeV) result energy and can spectra will be be of seen the in [ neutral pions for data for pp collision with energies of Figure 2: the decay of a neutral pion).The The left upper is two by panels the showthe small the transition tower, Si while curves microstrip taken the sensors; by right the Theidentifiable is two peaks upper by calorimeters; are the is from large the the tower. 1st four and The x-view 2nd lower data, layers, two while while panels the are the data the from lower the data is 3rd from the and 4th four layers y-view are data. almost zero. The icated to measurement of thea single simple photon criteria spectrum. based Events ontors. by the neutral longitudinal The hadrons development energy of are of the removed the by showers, remaining obtained photons by is the determined scintilla- from the same information on the light The LHCf experiment PoS(ENAS 6)066 , ◦ > ]. ine 20 13 η N , = 12 K. Noda φ ∆ < 8.99 and η ]. ] and PYTHIA 8.145[ 7 11 ]. 14 ], EPOS 1.9[ 10 ]. When the Si sensor is used as a calorimeter, 15 5 (GSO), which are more radiation-hard than the plastic 5 for Arm1 and Arm2, respectively. Multiplying it with an for the small towers, while 8.81 < SiO 2 1 ◦ − = 71.5 mb, we derived the number of inelastic collisions, ], SIBYLL 2.1 [ 9 360 ine σ = 53nb . φ ∆ 15 % up to 1.5 TeV [ ∼ and 0 1 − 14 TeV in 2014. A higher luminosity is expected for the 14 TeV runs than that 68nb ], QGSJET II-03 [ = . 8 s 0 shows the single-photon energy spectra obtained from a data set taken in pp collisions √ = 3 7 TeV in 2010. During the period for the data set, the integrated luminosity is estimated Ldt = ∫ Another upgrade is planned for the Arm2 detector. The current configuration of the Si mi- Now we are working on the following analyses for topics such as neutral pions, 900GeV As a result, we see that none of the model predictions nicely describe the LHCf data in the Figure s √ crostrip sensors distributed in thetion plastic using scintillators the are Si sensors. not If optimizedonly we for with change an the the energy Si configuration, reconstruc- an isoriginally improvement expected not of by considered the energy as a resolution a MCthe calorimeter, study, gain thus to calibration we using be require the less additional testhave than beam works obtained data 10%. for and a them. an However, gain MC the The factor simulationincident first Si for from particle is sensors the energy ADC same can were counts be configuration. reconstructed to We a from the simulation the energy for energy deposit, LHC deposit using configuration. on a Aresolution function the preliminary obtained for result Si by photons with sensors. a is MC Then data set the shows that the energy scintillators. The radiation hardness ofconfirmed the that GSO it has scintillator properties was good measured enough in for a our test use beam, [ and we photons, and Pt distribution ofwe photons are and preparing hadron spectra for at foreseencollisions 7 data at TeV acquisitions collisions. with the At the proton-ionin same collision the time, in 7 2012, TeV and runs. thescintillating fibers p-p Thus to ones we made are of Gd planning a hardware upgrade of the plastic scintillators and the whole energy range from 100 GeVenergy to region. 3.5 Discussions TeV. In about particular, thisImprovements there result of is with the a the hadron big model interaction discrepancy models developers in have are the been expected high in already near started. future. 5. Future prospects on the vertical axis.two The Arms, and black they points are compared are withDPMJET the results 3.04[ predicted energy by spectra MC simulations obtained using byLeft different models: and the right combination panels of refer the to the selected regions as mentioned before. to be at The LHCf experiment produced in the scintillators.efficiency, We and applied for corrections particles to leaking out it;we of used for the the non-uniformity lateral edges of positions of light oflayers. the showers collection calorimeter The determined towers. with information In the by this informationthat the by corrections has position the more sensitive position layers than sensitive one isconfigurations, showers also thus inside used in the to this same exclude analysis tower. ‘multi-hit’combine we events The the have two selected two Arms a spectra have common10.94 without different region and geometrical for any azimuthal each acceptance range tower correction. in order The to region is pseudo-rapidity assumed inelastic cross section for the large towers. Further details about the analysis are found in [ PoS(ENAS 6)066 K. Noda ° Energy[GeV] = 20 φ ∆ =7TeV < 8.99, s η -1 8.81 < LHCf Gamma-ray like Ldt=0.68+0.53nb ∫ Data 2010, Stat. + Syst. error DPMJET 3.04 QGSJET II-03 2.1 SIBYLL EPOS 1.99 8.145 PYTHIA Data 2010, 500 1000 1500 2000 2500 3000 3500 1 2 0 (2010) 091101. -4 -5 -6 -7 -8 -9 -3 -10 2.5 1.5 0.5

10 10 10 10 10 10 10

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MC/Data Events/N /GeV ]. Top panels show the spectra and bottom panels 104 7 , 6 = 7 TeV, and removed the detectors. The obtained s √ Measurement of the Depth of Maximum of Extensive Air Energy[GeV] ° = 360 φ ∆ Physical Review Letters =7TeV , s eV -1 > 10.94, 18 LHCf Gamma-ray like η 10 Ldt=0.68+0.53nb ∫ Data 2010, Data 2010, Stat. + Syst. error DPMJET 3.04 QGSJET II-03 2.1 SIBYLL EPOS 1.99 8.145 PYTHIA Comparison between the measured single-photon energy spectra (black dots) and the predictions 500 1000 1500 2000 2500 3000 3500 1 0 2 -5 -6 -7 -8 -9 -3 -4 Showers above -10 LHCf is a collider experiment dedicated for the cosmic-ray physics. It measures the energy 0.5 1.5 2.5

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ine MC/Data /GeV Events/N [1] J. Abraham et al. (Auger Collaboration), spectrum of very forward particlestematic generated errors in in pp air-shower collisions simulations in usedpaper LHC. in we ultra-high-energy Its brieﬂy cosmic-ray aim surveyed experiments. is our In todone detector this minimize the and data sys- the acquisition current for status pp collisions of at the experiment. We have already 6. Summary it would help not onlyevents, the which could calorimetry not of be the resolved scintillators, only by but the also scintillators. a separation of the ‘multi-hit’ Figure 3: of the following MC codes:(magenta) and DPMJET PYTHIA 3.04 (red), 8.145 QGSJET (yellow), II-03 taken (blue), from SIBYLL [ 2.1 (green), EPOS 1.99 photon spectra are not wellwe described are by working the for MChardware following expectations, upgrade analyses especially were in and also shown high foreseen in energies. detector this paper. upgrade. Now The prospectsReferences about the show the ratio of MCranges. results Error to bars show experimental the data. statisticalMagenta error Left shaded and areas gray and shaded indicate right areas the panels the statistical systematic refer error error associated to for to experimental different MC data. pseudo-rapidity simulations. The LHCf experiment PoS(ENAS 6)066 , 6 , , (2006) K. Noda (2009) 178 74 Physics JINST , , , , 80 , (HE3.1, 421), Physical Review D , ¯ ppS collider Physical Review C , Physical Review D (2011) 128. , 703 (2011) in press. , (2006) 026. (2008) 014904. Proceedings of the 32nd International 05 (2011) 21002. scintillator for heavy ion beam , 77 5 , 96 , Computer Physics Communications , SiO JHEP 2 , 7 Physics Letter B (2010) 161101. (HE1.4, 1335), , First measurement of the total proton-proton cross section Indications of Proton-Dominated Cosmic-Ray Composition 104 The LHCf detector at the CERN Large Hadron Collider Measurement of zero degree single photon energy spectra for , ’s in the fragmentation region at the S Energy spectrum of neutral pion at LHC proton-proton 0 Physical Review C Data analysis of the LHCf Si microstrip sensors π , Europhysics Letters , TeV 7 = (2011) in press. s √ Antiparticle to particle production ratios in hadron-hadron and d-Au collisions in PYTHIA 6.4 physics and manual A brief introduction to PYTHIA 8.1 Study of radiation hardness of Gd Parton ladder splitting and the rapidity dependence of transverse momentum spectra Nonlinear screening effects in high energy hadronic interactions Cosmic ray interaction event generator SIBYLL 2.1 Physical Review Letters , (1990) 531. Inclusive production of 242 (2008) S08006. , TeV proton-proton collisions at LHC 3 , 7 = (2006) 014026. s Letter B 74 (2011) T09004. Proceedings of the 32nd International Cosmic Ray Conference in deuteron-gold collisions at the BNL Relativistic Heavy Ion Collider JINST the DPMJET-III Monte Carlo model 094003. 044902. (2008) 852. at the LHC energy of √ above 1.6 EeV collisions measured by the LHCf experiment Cosmic Ray Conference [8] F. W. Bopp et al., [9] S. Ostapchenko, [7] O. Adriani et al. (LHCf Collaboration), [4] E. Pare et al, [5] O. Adriani et al. (LHCf Collaboration), [6] H. Menjo et al. (LHCf Collaboration), [2] R. U. Abbasi et al. (HiRes Collaboration), [3] G. Antchev et al. (TOTEM Collaboration), [15] K. Noda et al. (LHCf Collaboration), [12] T. Sjöstand et al., [13] T. Sjöstand et al., [14] K. Kawade et al., [10] E.-J. Ahn et al., [11] K. Werner et al., The LHCf experiment