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Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
The First Results of the LHCf experimentand future
Yoshitaka ItowSolar-Terrestrial Environment
LaboratoryNagoya University
for the LHCf collaboration
Catania Mini-WSJul 6, 2011, U.of Catania
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
2
Menu
Introduction to the LHCf experiment1st results from 7TeV collisionsOn-going activityLong term planDiscussion
Impact on air shower developmentImpact on very forward interaction
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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① Inelastic cross section
② Forward energy spectrum
If large krapid development
If small k deep penetrating
If large σrapid development
If small σdeep penetrating④ 2ndary interactions
③ Inelasticity k
If softershallow development
If harderdeep penetrating
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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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, JapanK.Yoshida Shibaura Institute of Technology, JapanK.Kasahara, M.Nakai, Y.Shimizu, T.Suzuki, S.Torii
Waseda University, JapanT.Tamura Kanagawa University, JapanY.Muraki Konan University, JapanM.Haguenauer Ecole Polytechnique, FranceW.C.Turner LBNL, Berkeley, USAO.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, H.Menjo, P.Papini, S.Ricciarini, G.Castellini
INFN, Univ. di Firenze, ItalyA.Tricomi INFN, Univ. di Catania, Italy J.Velasco, A.Faus IFIC, Centro Mixto CSIC-UVEG, SpainD.Macina, A-L.Perrot CERN, Switzerland
The LHCf Collaboration
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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140 m 140 m
n π0
γ
γ
8 cm 6 cm
The LHCf experimentNeutral particle measurement at 0 degree of LHC IP1
IP1 (ATLAS)IP1 (ATLAS)
ArmArm 22Arm 1Arm 1 Front Counter Front Counter
ATLAS
140m
140m
LHCf (Arm1)
LHCf (Arm2)
44X0, 1.6 λint
20mmx20mm+40mmx40mm4 SciFi tracking layers
25mmx25mm+32mmx32mm4 Silicon strip tracking layers
44X0, 1.6 λint
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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LHCf calorimeters
Arm#2 DetectorArm#1 Detector 90mm290mm
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Setup in IP1-TAN (side view)
LHCf Front Counter
LHCfCalorimeter
BRAN-IC
ZDC type1
IP1
ZDC type2
Beam pipe
TAN Neutral particles
Side view
BRAN-Sci
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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LHCf detector characteristicsSingle incident per tower with the small aperture as possible (comparable to tungsten Moliere radius)Shower leakage can be corrected by shower incident position.A pair of tower for π0 reconstructionMovable to cover PT gapCovered |η| > 8.4
Gamma-rays (E>100GeV,dE/E<5%)Neutral Hadrons (E>a few 100 GeV,
dE/E~30%)Neutral Pions (E>700GeV, dE/E<3%)
Shower incident position (170µm / 40µm for Arm1/Arm2
σ=40μmfor 200GeVelectrons
9
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011Calorimeter acceptance (viewed from IP)
θ[μrad]
0
310
0 crossing angle
100urad crossing angle
Projected edge of beam pipe
beam1 beam2
Neutral fluxcenter
Neutral flux
center
crossing angle
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Forward E spectra by LHCf @ 14TeV (MC for ~0.1nb-1)
π0
single γ
Neutrons (w/ 30% resolution)
Neutrons (true energy)
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Brief history of LHCfMay 2004 LOI
Feb 2006 TDR
June 2006 LHCC approved
Jan 2008 Installation
Aug 2007SPS beam test
Sep 20081st LHC beam
Jul 2006construction
Mar 20101st 7TeV run
Dec 20091st 900GeV run Jul 2010
Detector removal
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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2009-2010 run summary (7TeV)
106
107
108
Integrated showers at 7TeV
# of
sho
wer
s
Dete
ctor
rem
oved
High luminosity (L=3~20e29cm2s-1)(1e11ppb, b*=3.5m,Nb=1~8)100µrad crossing
Arm1 π0 stat.
Low luminosity (L=2~10e28cm2s-1)(1~2.5e10ppb, β∗=2m,Nb=1~4) No crossing angle
500K
1000K
# of
π0
900GeV
4/1 5/27 7/22
4/4 5/30 7/25
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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The first paper
• Limited Data :o 15 May 2010 17:45‐21:23, Low Luminosity 6x1028o 0.68 nb‐1 for Arm1, 0.53nb‐1 for Arm2
• “Single” γ energy spectra for two Psudo-rapidity bins,o eta > 10.94, 8.81 < eta < 8.99
" Measurement of zero degree single photon energyspectra for√s = 7 TeV proton-proton collisions at LHC “
(submitted to PLB, arXiv:1104.5294, CERN-PH-EP-2011-061 )Video available for seminar by Sako at CERN
http://indico.cern.ch/conferenceDisplay.py?confId=137111
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Typical event display (7TeV π0 )TeV π0 !
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Energy reconstructionEphoton = f(Σ(dEi)) (i=2,3,…,13)
( dEi = AQi determined at SPS. f() determined by MC. E : EM equivalent energy)Shower incident positions by position sensitive layers.Position dependence corrections– Light collection non-uniformity– Shower leakage-out / leakage-in
– Energy scale – Calibrated with SPS 150-250 GeV e- beam– Check with π0 mass peak in 7TeV data
( Arm1 (+7.8%) , Arm2 (+3.7%) )
15pi0mass (arm1) pi0mass (arm2)
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Multi-incident rejection Single shower event selection– Reject two shower hits in a tower by a lateral shape
16
Arm1 Small
Dou
ble hit d
etection
efficiency
Arm2 small
0 1 2 3 (TeV) 0 1 2 3 (TeV)
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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PID ( γ / hadron separation)PID ( γ-like shower selection)– Select γ-like events in L90% distribution and correct ε
(efficiency) and P (purity)
17
γ had
Definition of L90%
18
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
Select rapidity regions
Consistency check btw Arm1 and Arm2
19
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
Arm1+Arm2 combined spectra
Normalized by number of inelastic pp collisions with assumption as total inelastic cross section of 71.5mb
20
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
Comparison with Models
DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145
21
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
Spectral deformation bias• Suppression due to multi-hit cut at medium energy• Overestimate due to multi-hit detection inefficiency
at high energy (mis-identify multi photons as single)• No correction applied, but same bias included in MC
to be compared
TRUEMEASURED
TRU
E/M
EASU
RED
True: photon energy spectrum at the entrance of calorimeter
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Systematic errors
Spectrum shapeE-scale Multi-shower rejection efficiency PID efficiency / purity subtractionNeutral flux center
Absolute Lumi measurement by FC (calibrated by VdM-scan)Normalized by number of inelastic pp collisions
with assumption as total inelastic cross section of 71.5mb
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
23syst
emat
ic e
rror
s on
sha
pe
23
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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On-going analyses
7TeV data900GeV data
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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2009-2010 900GeV analysis
900 GeV run (no crossing angle)06 Dec. –15 Dec. 2009 (27.7 hrs, 500K collisions)
2.8K / 3.7K single showers at Arm1 / Arm202 May – 27 May in 2010 (15hrs, 5.5M collisions)
44K / 63K single showers at Arm1 / Arm2
• Because LHCf can cover only small PT region at < 450GeV, PT distribution will not be provided.
• No possibility of detection of pi0, eta and etc
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Particle ID
L90% @ 40mm cal. of Arm1
MC (QGSJET2)Data
Prelim
inary
Thick for E.M. interaction (44X0) Thin for hadronic interaction(1.7λ)
A transition curve for Gamma-ray A transition curve for Hadron
Definition of L90%
Gamma-ray like
• ~ 90% efficiency with ~10% contamination
Hadron like
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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900GeV spectra Eff. uncorrected, stat.error onlyNormalized by total # of events.
GammaGamma--ray likeray like Hadron likeHadron like
GammaGamma--ray likeray like Hadron likeHadron like
Arm
1A
rm1
Arm
2A
rm2
Prelim
inary
Prelim
inary
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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On-going work for 7TeV dataFor Photons (>100GeV)
Energy spectrum in wider rapidity rangePT distribution as a function of photon energy
For Hadrons (> some hundreds GeV)Energy Spectrum and PT distribution with less precision.Energy resolution for hadrons is about 30%.
For Pi0's (>500GeV)Energy spectrum and PT distribution.
For Eta, K0S and Lambda
Maybe only some information can be provided, like production ratio of Eta/Pi0.
With double side coincidence,With Central information from ATLAS
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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PT distribution for photonspp 7TeV, EPOS
1TeV<Eg<1.1TeV
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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7TeV study: Reconstruction of η
π0 Candidate
η Candidate
Prelim
inary
Another good energy calibration point.Production yield of η much differs among the models.
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
31
LHCf future run plan
Jul
7TeV
2010 2013 2014
LHCf I
14TeV
LHCf II
Detector upgrade
LHC2011/2012
shutdown
Re-
inst
all
102010171014 eV
14TeV7 100.9TeV
KneeGZK
Ankle
AUGER, TATALE
2nd Knee?
Re-
inst
all?
LHCf-HI Replace with rad-hardGSO scintillator
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
32
Foreseen “corrected” π0 spectrum at 14TeV (MC)
Uncertainty of Multi Hit contamination Uncertainty of energy scale : assumed as ±5%Uncertainty of relative normalization btw 2 pos. <0.1%Uncertainty of neutral beam center <0.1%
Peak=134MeVσ=4.9MeV
Cut 125MeV- 145MeV
Based on ~104 π0 samples at 2 positions Mass cut
π0 energy resolution
H.Mejo,Astropart.Phys. 34 (2011) 513-520
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Coverage at 7TeV and 14TeV
All γ from IP
N
L
7TeV collisions
7 TeV 14 TeV
34
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011Measurement at several collisions energy
7 TeV10 TeV14 TeV (1017eV@lab.)
SIBYLL
7 TeV10 TeV14 TeV
QGSJET2
Secondary gamma-ray spectra in p-p collisions at different collision energies (normalized to the maximum energy)
SIBYLL predicts perfect scaling while QGSJET2 predicts softening at higher energy
Qualitatively consistent with Xmax prediction
Note: LHCf detector taken into account (biased)
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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LHCf-HI ?p-Pb relevant to CR physics?CR-Air interaction is not p-p, but A1-A2 (A1:p, He,…,Fe, A2:N,O)
LHC Nitrogen‐Nitrogen collisionsTop: energy flow at 140m from IPLeft : photon energy spectra at 0 degree
35
TotalNeutronPhoton
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Discussion
Impact on air shower development
Impact on very forward interaction
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
37
π0 spectrum and air shower
Artificial modification of meson spectra and its effect to air showerImportance of E/E0>0.1 mesonsIs this modification reasonable?
37
π0 spectrum at Elab = 1019eV
QGSJET II originalArtificial modification
Longitudinal AS development
Ignoring X>0.1 meson
X=E/E0
30g/cm2
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Very forward – connection to low-x physics
Very forward region : collision of a low-x parton with a large-x partonGluon become dominating in higher energy collision by self interaction.But they may be saturated (gluon satruration)
Increasing E
Low-x high-x
But LHCf sees much lower PT, soft interactions
soft hard semi-hard
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
39
SummaryLHCf : Dedicated measurements of neutral particles at 0 deg at LHC energy for the verification of cosmic rays interaction models at 1017eV.Phase-I run successfully completed. Analysis on-going.
900 GeV run : ~ 100K showers in both arms7 TeV runs : ~300M showers, ~1M π0 in both armsDetector worked as designed. We can say something about model discrimination soon.
Revisit LHC for next energy upgrade at ~2014 with a rad-hard detector. Possible future Light Ion runs? R&D in progress.
UHECR data may hint ultra high energy interactions at beyond-LHC energy. To approach, LHCf will give firm base of understanding at 1017eV.
41
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011
P-Pb collisionsWe are starting studies of measurement at p-Pb collisions with LHCf detectors.
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
42
Contribution from very forward production5×1019 eV proton showers( 60 deg zenith)
# of
ele
ctro
ns
No cut
low XF γ origin ( xF < 0.05 )
π,Κ origin ( xF < 0.1 )
Half of shower particles comes from large XF γ
Measurement at very forward region Is needed
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
43
Next stepRevisit LHC when next energy upgrade (i.e. @14 TeV in 2013).
Detector will be upgraded with rad-hard GCO scintillatorLight ion collisions to understand nuclear effects.
So far only heavy ions (Pb-Pb) collisions are forseen( in late 2010) at LHC, in which too much multiplicity for LHCf .Feasible study under going to cope with high multiplicity at 0 degree for light ions
0.5 particle/cm^23.5TeV/n N- N collisionsMulitiplicity in 0-1cm cone at 140m
DPMJET3QGSJET2
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
44
Energy reconstructionEphoton = f(Σ(dEi)) (i=2,3,…,13)
( dEi = AQi determined at SPS. f() determined by MC. E : EM equivalent energy)Shower incident positions by position sensitive layers.Position dependent corrections– Light collection non-uniformity– Shower leakage-out– Shower leakage-in (in case of two calorimeter event)
44Light collection nonuniformity Shower leakage‐out Shower leakage‐in
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
45
Multi-incident rejection Single event selection– Single-hit detection efficiency– Multi-hit identification efficiency (using superimposed
single photon-like events)– Effect of multi-hit ‘cut’ (next slide)
45
Double hit in a single calorimeter
Single hit detection efficiency
Small tower Large tower
Double hit detection efficiency
Arm1
Arm2
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
46
Uncertainty in Step.2Fraction of multi-hit and Δεmulti, data-MC
Effect of multi-hit ‘cut’ : difference between Arm1 and Arm2
46Single / (single+multi), Arm1 vs Arm2Effect ofΔεmulti to single photon spectra
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
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Uncertainty in Step.3Imperfection in L90%distribution
47
Template fitting A
Template fitting B
(Small tower, single & gamma‐like)
Artificial modification in peak position (<0.7 r.l.) and width (<20%)
Original method
ε/P from two methods
(ε/P)B/ (ε/P)A
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
48
Analysis Step.4π0 identification from two tower events to check absolute energyMass shift observed both in Arm1 (+7.8%) and Arm2 (+3.7%)No energy scaling applied, but assigned the shifts in the systematic error in energy
48
m 140=R
θ
I.P.1θ
γ1(E1)
γ2(E2)
140mR
Arm2 Measurement
Arm2 MC
M = θ√(E1xE2)
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
49
Beam Related Effects
Pile-up (7% pileup at collision)Beam-gas BGBeam pipe BGBeam position (next slide)
49
MC w/ pileup vs w/o pileup
Crossing vs non‐crossing bunches Direct vs beam‐pipe photons
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
50
Where is zero degree?
50Effect of 1mm shift in the final spectrum
Beam center LHCf vs BPMSW
LHCf online hit‐map monitor
Y.Itow, The first results of the the LHCf experiment and future LHCf Catania@ 6 Jul 2011
51
Luminosity EstimationLuminosity for the analysis is calculated from Front Counter rates:
The conversion factor CF is estimated from luminosity measured during Van der Meer scan
LVDM = nb f revI1I2
2πσ xσ yVDM scan
BCNWG paperhttps://lpc‐afs.web.cern.ch/lpc‐afs/tmp/note1_v4_lines.pdf
L = CF × RFC
Beam sizes σx and σy measured directly by LHCf
52
Y.Itow, The first results of the LHCf experiment and future LHCf Catania@ 6 Jul 2011Geometrical Efficiency for Pi0, Eta
Pi0
Eta