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Latest LHCf physics results
Oscar AdrianiUniversity of Florence & INFN Firenze
ICHEP 2014Valencia, July 4th, 2014
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Extensive air shower observation • Longitudinal distribution • Lateral distribution • Arrival direction
Astrophysical parameters • Spectrum• Composition• Source distribution
Air shower development
HECRs
Xmax is the depth of air shower maximum inthe atmosphere. An indicator of CR composition.
Uncertainty of hadron interaction models
Uncertainty in the interpretation of <Xmax>
High Energy Cosmic Rays
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
④ secondary interactionsnucleon, p
① Inelastic cross section
If large : s rapid developmentIf small :s deep penetrating
② Forward energy spectrum
If softer shallow developmentIf harder deep penetrating
If large k (p0s carry more energy) rapid developmentIf small k (baryons carry more energy) deep penetrating
How accelerator experiments can contribute?
③ Inelasticity k=1-Elead/Eavail
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Models tuning after the first LHC data
Xmax as function of E and particle type
Significant reduction of differences btw different hadronic interaction models!!!
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
LHCf: location and detector layout
44X0, 1.6 lint
INTERACTION POINT
IP1 (ATLAS)
Detector IITungsten
ScintillatorSilicon
mstrips
Detector ITungsten
ScintillatorScintillating
fibers140 m 140 m
n π0
γ
γ8 cm 6 cm
Front Counter Front Counter
Arm#1 Detector20mmx20mm+40mmx40mm4 X-Y SciFi tracking layers
Arm#2 Detector25mmx25mm+32mmx32mm4 X-Y Silicon strip tracking layers
Energy resolution: < 5% for photons 30% for neutronsPosition resolution: < 200μm (Arm#1) 40μm (Arm#2)Pseudo-rapidity range:η > 8.7 @ zero Xing angleη > 8.4 @ 140urad
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
LHCf ‘analysis matrix’
Proton equivalent energy in
the LAB (eV)
g Neutrons p0
SPS Test beam
NIM A, 671, 129 (2012)
JINST 9 P03016 (2014)
p-p 900 GeV 4.3x1014
Phys. Lett. B 715, 298
(2012)
p-p 7 TeV2.6x1016 Phys. Lett.
B 703, 128 (2011)
In preparation
Phys. Rev. D 86, 092001
(2012)
p-p 2.76 TeV4.1x1015
Phys. Rev. C 89, 065209
(2014)p-Pb 5.02 TeV
1.3x1016
p-p 7 TeV9.0x1016 Waiting for LHC restart!
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
The challenge of neutron analysis
Performance for 1.5 TeV neutrons:
DE/E ~35%-40% Dx ~ 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
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Inclusive neutron spectra (7 TeV pp)Bef
ore
unfo
ldin
g
Aft
er u
nfol
ding
Very large high energy peak in the h>10.76 (predicted only by QGSJET) Small inelasticity in the very forward region!
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
3.5cm,4.0cm
The 2013 p-Pb run at sNN = 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 = 1x1029 – 0.5x1029cm-2s-1
– ~200.106 events– b* = 0.8 m, 290 mrad crossing angle– 338p+338Pb bunches (min.DT = 200 ns), 296 colliding at
IP1– 10-20 kHz trig rate downscaled to approximately 700 Hz– 20-40 Hz ATLAS common trig. Coincidence successful! – p-p collisions at 2.76 TeV have also been taken p
Pb
IP8IP2IP1
Arm2
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
proton
impactparameter : bproton Pb
Central collisions
(Soft) QCD :central and peripheral collisions Ultra peripheral collisions :
virtual photons from rel. Pb collides a proton
Dominant channel to forward p0 is
About half of the observed π0 originate from UPCAbout half is from soft-QCDNeed to subtract UPC component
Break downof UPC
Comparisonwith soft-
QCD
LHCf @ pPb 5.02 TeV: p0 analysis
Peripheral collisions
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 approximation2. photon-proton collisions are simulated by the SOPHIA model (Eγ > pion threshold)
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
p0 event reconstruction in p-Pb collisions
travel in beam pipe (140m)
1. Search for two photons 2. BG subtraction by sideband
4. Subtraction of the UPC component
LHCf data
UPC MC (x0.5)
3. Unfolding the smeared pT spectra andcorrection for geometrical inefficiency
π0 detection efficiencyp-Pb √s=5.02TeV
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Inclusive p0 pT 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.
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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 pT, as can be expected
by the pT spectrum that is softer in p-p 5 TeV than in p-Pb 5 TeV collisions
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Conclusions Very forward p0 production in p-Pb collision has been
measured by LHCf
Soft-QCD component of the measured p0 production overall agrees with DPMJET 3.04 and EPOS 1.99.
Strong suppression of p0 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: LHC@13 TeV in 2015 510 GeV polarized p-p RHIC run in 2016 has been proposed to
RHIC PAC. We are waiting for official answer
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
O.Adriania,b, L.Bonechib, E.Bertia,b, M.Bongia,b, G.Castellinic,b,
R.D’Alessandroa,b, M.Del Pretea,b,M.Haguenauere, Y.Itowf,g,
K.Kasaharah, K. Kawadeg, Y.Makinog, K.Masudag, Y.Matsubarag,
E.Matsubayashig, H.Menjoi, G.Mitsukag, Y.Murakig, P.Papinib, A.-
L.Perrotj, D.Pfeifferj, S.Ricciarinic,b, T.Sakog, Y.Shimitsuh,
Y.Sugiurag, T.Suzukih, T.Tamurak, A.Tiberioa,b, S.Toriih, A.Tricomil,m,
W.C.Turnern, K.Yoshidao, Q.Zhoug
a) University of Florence, Italyb) INFN Section of Florence, Italy c) IFAC-CNR, Florence, Italyd) IFIC, Centro Mixto CSIC-UVEG, Spaine) Ecole Polytechnique, Palaiseau, Francef) KMI, Nagoya University, Nagoya, Japang) STELAB, Nagoya University, Japanh) RISE, Waseda University, Japani) School of Science, Nagoya University, Japanj) CERN, Switzerlandk) Kanagawa University, Japanl) University of Catania, Italym) INFN Section of Catania, Italyn) LBNL, Berkeley, California, USAo) Shibaura Institute of Technology, Japan
The LHCf Collaboration
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Muon excess at Pierre Auger Obs.
Pierre Auger Collaboration, ICRC 2011 (arXiv:1107.4804)
Pierog and Werner, PRL 101 (2008) 171101
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 MCEPOS predicts more muon due to larger baryon production => importance of baryon measurement
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Derivation of p0 pT spectra in p-p at 5.02 TeV
1. Thermodynamics (Hagedorn model)
2. Gauss distribution
The pT spectra in “p-p at 5.02TeV” are obtained by the Gauss distribution with the above <pT> and absolute normalization.
22
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
The importance of neutrons in the very forward region
Motivations:• Inelasticity measurement: k=1-pleading/pbeam
• Muon excess at Pierre Auger Observatory• cosmic rays experiment measure HECR
energy from muon number at ground and florescence light
• 20-100% more muons than expected have been observed
Number of muons depends on the energy fraction of produced hadronMuon excess in data even for Fe primary MCEPOS predicts more muon due to larger baryon production
R. Engel importance of baryon measurement
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
PRELIMINARY
PRELIMINAR
Y
p-Pb run: p0
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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 8.145 QGSJET II-03
Gray hatch : Systematic Errors
Magenta hatch: MC Statistical errors
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
DATA vs MC : comp. 900GeV/7TeV9
00
GeV
7Te
V
η>10.94 8.81<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
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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 XF > 0.1)Data 2010 at √s=7TeV (η>10.94)
900GeV vs. 7TeVwith the same PT region
Normalized by the number of entries in XF > 0.1 No systematic error is considered in both collision
energies.
XF spectra : 900GeV data vs. 7TeV data
small-η
Coverage of 900GeV and 7TeV results in Feynman-X and PT
Good agreement of XF spectrum shape between 900 GeV and 7 TeV.weak dependence of <pT> on ECMS
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
p0 PT 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 8.145
0 0.6PT[GeV]
0 0.6PT[GeV] 0 0.6PT[GeV] 0 0.6PT[GeV]
0 0.6PT[GeV] 0 0.6PT[GeV]
MC
/Data
MC
/Data
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
p0 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 <pT> on ECMS.
• Smallest dependence on ECMS is found in EPOS and it is consistent with LHCf and UA7.
• Large ECMS dependence is found in SIBYLL
PLB 242 531 (1990)
ylab = ybeam - y
Submitted to PRD (arXiv:1205.4578).
pT spectra vs best-fit function Average pT vs ylab
YBeam=6.5 for SPSYBeam=8.92 for7 TeV LHC
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
Determination of energy from total energy release
PID from shapeDetermination of the impact point
Measurement of the opening angle of gamma pairs
Identification of multiple hit
25mm Tower 32mm 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 p0 in Arm2
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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 RHICLower 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 – Air @ knee energy.
10cm
detector
LHCf: future plan
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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) √sNN=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) 152302
Nuclear modification factor at d-Au 200GeV
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
η
∞
8.5
What LHCf can measure
Energy spectra and Transverse momentum distribution of
Multiplicity@14TeV Energy Flux @14TeV
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%)• π0 (E>600GeV, dE/E<3%)
at pseudo-rapidity range >8.4
Front view of calorimeters @ 100μrad crossing angle
beam pipe shadow
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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
MCimpact parameter vs. # of particles in ATLAS LUCID
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O. Adriani Latest LHCf physics results Valencia, July 4th, 2014
L90%L20%
Layer[r.l.]
hadronphoton
projection along the sloped
line
L 90
%
L20%
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
• L20%(L90%): depth in X0 where 20% (90%) of the deposited energy is contained
• L2D=L90%-0.25 L20%
• Mean purity in the 0-10 TeV range: 95%
• Mean efficiency: ~90%
L2D