Presentation on theme: "The First Results from the LHCf experiment and Cosmic-Ray Physics Yasushi Muraki Department of physics, Konan University, Kobe, Japan On behalf of the."— Presentation transcript:
The First Results from the LHCf experiment and Cosmic-Ray Physics Yasushi Muraki Department of physics, Konan University, Kobe, Japan On behalf of the LHCf collaboration Contents 1. Experimental purposes 2. Experiment details 3. The first result of the highest energy photon spectrum obtained by the highest energy accelerator 4. Impact on the cosmic-ray physics CRIS2010, September 17th, 2010
K.Fukatsu, Y.Itow, K.Kawade, T.Mase, K.Masuda, Y.Matsubara, G.Mitsuka, K.Noda, T.Sako, K.Suzuki, K.Taki Solar-Terrestrial Environment Laboratory, Nagoya University, Japan K.Yoshida Shibaura Institute of Technology, Japan K.Kasahara, M.Nakai, Y.Shimizu, T.Suzuki, S.Torii Waseda University, Japan T.Tamura Kanagawa University, Japan Y.Muraki Konan University, Japan M.Haguenauer Ecole Polytechnique, France W.C.Turner LBNL, Berkeley, USA O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, H.Menjo, P.Papini, S.Ricciarini, G.Castellini INFN, Univ. di Firenze, Italy A.Tricomi INFN, Univ. di Catania, Italy J.Velasco, A.Faus IFIC, Centro Mixto CSIC-UVEG, Spain D.Macina, A-L.Perrot CERN, Switzerland The LHCf Collaboration
preface One of the main problems of cosmic-ray study is the energy determination. Castagnoli method Calorimeter method Shower method We have developed many techniques like Transition radiation detector, NKG function, etc Still it is a problem of the balloon flight to use a shallow depth calorimeter, e.x., RUN-job, JACEE etc, fluctuation is sooo large. Chudakov proposed to launch a satellite for fixing the mass composition Problem at Moscow cosmic ray conference in 1987 to fix the problems around the knee region. We have been called by Chdakov and assembled in a room in the together with VIPS of Academician like Ginzburg. But Soviet Union collapsed and this idea have never been realized.
1. The experimental Purpose The main purpose of this experiment is to establish the production cross- section of pions at the very forward region in proton-proton interactions at the highest energy region, using the highest energy accelerator in the world. It has been dream of cosmic ray physicists for a long time. To realize above purpose, we propose to install a compact calorimeter in front of the beam intersection at 140m away. It would be the smallest experiment using the largest accelerator in the world. We require a rather low luminosity operation, say and rather small bunches in a ring, say ~23 in a circle. ( In fact it was a few bunches) By this experiment, we will be able to establish a very important data point, which will be very useful to understand for not only the highest energy cosmic ray problems, but also for establishing the forward code of the GEANT 4 17 th Rencontre de Blois, 5/16/2005 and LHCC
Experimental Purpose Prepared by TOKO san in 2006
Present status : TA results appeared Very good talks have been given in this conference by B. Dawson and J. Matthews
The position of shower maximum Knapp et al, Astroparticle Physics, 19(2003) 77 UA7 LHCf Fe incidence
x F <0.05 x F <0.1 The right side curve shows when we measure only the particles emitted into the Feynman X F <0.05, we only measure half of the energy flow into the showers. So the measurement of the very forward direction will be very important. Why Very Forward?
Why forward? Why near the beam pipe? To understand cosmic ray problems, it is necessary to measure the differential cross-section of the particles emitted into the very forward cone, While accelerator people love to measure heavy particles emitted at the central region θ≈ 90 o
Technical Report on the CERN LHCf experiment 12 Oct Measurement of Photons and Neutral Pions in the Very Forward Region of LHC O. Adriani(1), L. Bonechi(1), M. Bongi(1), R. D’Alessandro(1), D.A. Faus(2), M. Haguenauer(3), Y. Itow (4), K. Kasahara(5), K. Masuda(4), Y. Matsubara(4), H. Menjo(4), Y. Muraki(4), P. Papini(1), T. Sako(4), T. Tamura(6), S. Torii(7), A. Tricomi(8), W.C. Turner(9), J. Velasco(2), K. Yoshida(6) 1. Review of experimental purpose 2. The results of the test experiment 3. Trigger, Beam condition, Schedule, Concluding remarks To realize this idea, we have proposed to install a small calorimeters inside the small gap at 140m away from the interaction point. In the region heavy iron material, TAN is located in order to absorb strong high-energy neutron beam produced by the pp collisions.
Detector location Y Chamber
2. Experimental Details Arm1 and Arm2 detectors The calorimeters are composed of the tungsten material with the total 44 radiation length, and 1.6 interaction mean free path. 4 layers are prepared for the identification of the shower center by using either the scintillation fiber (Arm1) or the silicon strip detector (Arm2). This guarantees not only the cross-check of the measurement but also it makes possible the single diffractive events and double diffractive events. To obtain the large acceptance ( P T range) to the photons, the calorimeter can be lifted up and down by the remote manipulator.
Examples of simulated events for and n
Configuration of the two calorimeters in the beam pipe 44 radiation length or 1.6 interaction mean free path
Detector vertical position and acceptance Remotely changed by a manipulator( with accuracy of 50 m) Distance from neutral center Beam pipe aperture Data taking mode with different position to cover P T gap N L G All from IP Viewed from IP Neutral flux center N L 7TeV collisions Collisions with a crossing angle lower the neutral flux center to enlarge P T acceptance
Actual setup in IP1-TAN (side view) LHCf Front Counter LHCf Calorimeter BRAN-IC ZDC type1 IP1 ZDC type2 Beam pipe TAN Neutral particles Side view BRAN-Sci
Performance of the LHCf calorimeters Energy resolution ≈ 1TeV Position resolution 160μm for Arm1 and 49 μm for Arm2 PMT response to the showers from 1 particle (muon) to 10 5 particles (induced by 1 TeV photon) (no saturation) Particle Identification (PID) ( γ/n, quite well separated ) Leakage correction from the edge of the calorimeter tower ( confirmed by the SPS experiment). We only use the showers that hit 2mm inside from the edge.
Actual data-taking 10 8 events =100Mevents
Total number of events collected Trigger patternArm1Arm2 Shower trigger50M55M Two Showers in both calorimeters 20M25M with crossing angle 7TeV, without crossing angle, normal HV shower trigger154M138M (1nb -1 ~ 10 8 collisions ~ 10 7 showers)
Measured Spectra at 7TeV preliminary Gamma-ray like Hadron like Arm2 preliminary Gamma-ray like Hadron like Arm1 Very high statistics !! only 2% of all data Comparisons with MC are on-going.
The energy spectrum of photons by Arm1 and Arm2 detectors Red : Arm1 Blue : Arm2: the same rapidity region has been chosen only adjusted by the detection time Energy scale is preliminary about±2%
7TeV results: Reconstruction of 0 Candidate η Candidate Another good energy calibration point. Production yield of much differs among the models. Preliminary
0 reconstruction ΔM/M=2.3% Reconstructed Arm2 measured energy Arm2 preliminary An example of 0 events Pi0’s are a main source of electromagnetic secondaries in high energy collisions. The mass peak is very useful to confirm the detector performances and to estimate the systematic error of energy scale. 25mm 32mm Silicon strip-X view
Examples of simulated events for and n
The particle identification (PID) between photons and neutrons by Nakai
When we insist the efficiency to squeeze photons as constant, hadrons will be involved at the highest energy region
When we make a criterion that the 90% energy of photons must be involved in the 18 layers from the beginning, the rate of gamma-rays increases but the catching efficiency of photons will go down. Neutrons will be involved.
The energy spectrum of photons at √s=7TeV by different criterion of L=5.5×10 28 / cm 2 sec
However if we can make appropriate correction to each criterion, we can reduce the photon spectrum.
Matters to be checked before publication Linearity of photo-tubes (PMT) Leakage from the corner Energy resolution ( Particle identification Multi-hit correction Beam-gas contamination(<0.1%?) pile-up effect ( <0.7% depends on the luminosity) Energy flow from the other calorimeter in multi-hit (5-7%) Absolute energy calibration ( ±2%) So still results are preliminary but things go to good direction.
The next target of the LHCf The differential cross-section of photons at 7TeV A promise from the LHCf Until the time that we must submit our paper for the proceeding, we will be able to fix several problems. Details should be asked to Oscar Adriani (Firentze) or Alessia Tricomi (Catania) a few weeks later.
The effect of our results to cosmic-ray physics (a personal view 1) Tibet AS array with Water (prospect) The Ne-Nμ spectrum Gamma/hadron separation
The effect of our results to cosmic-ray physics (a personal view 2) New data of TA and relation between Auger, Hi-Res and AGASA Preliminary
advertisements There will be held an international conference in related with the highest energy cosmic rays and LHCf at Nagoya international conference hall in Dec , The convenient air lines are LH and Air Fin, direct flight to Nagoya (central Japan airport). From central Japan airport, 30 minutes by the train.
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Acknowledgements We thank to the organizers for a beautiful conference!
A brief history of the LHCf experiment May Letter of Intent Oct Technical report Feb Technical Design Report Jun LHCC approved July 2007 construction starts Aug SPS beam test Jan SPS installation Sep First beam at LHC Dec GeV run Mar TeV run July 2010 Removal of the LHCf detector from IP1