latest lhcf physics results

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Latest LHCf physics resultsOscar AdrianiUniversity of Florence & INFN Firenze

ICHEP 2014Valencia, July 4th, 2014

+Physics MotivationsImpact on HECR Physics

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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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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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Models tuning after the first LHC data

Xmax as function of E and particle type

Significant reduction of differences btw different hadronic interaction models!!!

+LHCf @ LHCThe experimental set-up

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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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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 4.3x1014Phys. Lett. B 715, 298

(2012)

p-p 7 TeV 2.6x1016 Phys. Lett. B 703, 128

(2011)In

preparationPhys. Rev. D 86, 092001

(2012)

p-p 2.76 TeV 4.1x1015

Phys. Rev. C 89, 065209

(2014)p-Pb 5.02 TeV

1.3x1016

p-p 7 TeV 9.0x1016 Waiting for LHC restart!

+Latest analysisNeutrons in 7 TeV pp collisions p0 in 5.02 TeV p-Pb collisions

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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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Inclusive neutron spectra (7 TeV pp)Be

fore

unf

olding

Afte

r unf

olding

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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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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protonimpactparameter : 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 p0 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 (E γ > pion threshold)

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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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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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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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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

+Backup slides


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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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UPC subtraction

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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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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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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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PRELIMINARY

PRELIMINAR

Y

p-Pb run: p0

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Comparison wrt MC Models at 7 TeVDPMJET 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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DATA vs MC : comp. 900GeV/7TeV90

0GeV

7TeV

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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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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p0 PT spectra for various y bin: MC/dataEPOS 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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p0 Data vs MC at 7 TeV cm

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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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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 Tower600GeV 　　 photon

420GeV 　　 photon

Longitudinal development measured by scintillator layers

Transverse profile measured by silicon m–strip layers

`

X-view

Y-view

`

Reconstruction of p0 mass:

A very clear p0 in Arm2

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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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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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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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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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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

latest lhcf physics results

Documents

3x1016 pp

p collisionsinstallation

physics motivationsimpact

lhcf status

tev ppb collisions

latest analysisneutrons

lhcf analysis matrixo

p inelastic cross section