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Preliminary results on neutral particles in the forward region at - - PowerPoint PPT Presentation

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Workshop on Hadron-Hadron & Cosmic-Ray Interactions at multi-TeV Energies ECT* - Trento, Nov 29th - Dec 3rd, 2010 Preliminary results on neutral particles in the forward region at LHC with the LHCf experiment Massimo Bongi - INFN

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Preliminary results

  • n neutral particles in the

forward region at LHC with the LHCf experiment

Massimo Bongi - INFN (Florence, Italy) LHCf Collaboration

Workshop on Hadron-Hadron & Cosmic-Ray Interactions at multi-TeV Energies ECT* - Trento, Nov 29th - Dec 3rd, 2010

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Hadron-Hadron & Cosmic-Ray Interactions at multi-TeV Energies

  • Recent excellent observations (e.g. PAO, HiRes, TA) but the
  • rigin and composition of UHECR is still unclear
  • Uncertainty in hadron-hadron interactions affects:

– the prediction of Xmax – SD observations

  • Study of very forward

particle emission at as high as possible energy is indispensable

LHC forward (LHCf) experiment

  • AUGER
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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

CR <=> LHC connection

  • The dominant contribution to the energy flux in the atmospheric

shower development comes from the very forward produced particles

  • Precise measurement of , 0 and n spectra in the very forward

region at LHC

  • 7 TeV + 7 TeV in the CM frame  ~1017 eV in “fixed target” frame

LHC CR CR

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

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 and Universita’ di Firenze, Italy

A.Tricomi

INFN and Universita’ di Catania, Italy

J.Velasco, A.Faus

IFIC, Centro Mixto CSIC-UVEG, Spain

D.Macina, A-L.Perrot

CERN, Switzerland

The LHCf Collaboration

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

96mm ATLAS

140m

LHCf Detector (Arm1)

ATLAS LHCb CMS/TOTEM ALICE LHCf

Experimental set-up

Beam pipe Protons Charged particles (+) Charged particles (-) Neutral particles

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Particle and energy flow vs pseudorapidity

Multiplicity @ 14TeV Energy Flux @ 14TeV Low multiplicity High energy flux

simulated by DPMJET3

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm1 detector

Scintillating Fibers + MAPMT: 4 pairs of layers (at 6, 10, 30, 42 X0), tracking measurements (resolution < 200 μm) Plastic Scintillator: 16 layers, 3 mm thick, trigger and energy profile measurement 40mm 20mm Absorber: 22 tungsten layers, 44 X0, 1.7 

  • Sampling E.M. calorimeters:

each detector has two calorimeter towers, which allow to reconstruct 0

  • Front counters:

thin plastic scintillators, 80x80 mm2

  • monitor beam condition
  • rejection of background due to beam -

residual gas collisions by coincidence analysis

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

25mm 32mm

Arm2 detector

Plastic Scintillator: 16 layers, 3 mm thick, trigger and energy profile measurement Absorber: 22 tungsten layers, 44 X0, 1.7 

  • Sampling E.M. calorimeters:

each detector has two calorimeter towers, which allow to reconstruct 0

  • Front counters:

thin plastic scintillators, 80x80 mm2

  • monitor beam condition
  • rejection of background due to beam -

residual gas collisions by coincidence analysis

Silicon Microstrip: 4 pairs of layers (at 6, 12, 30, 42 X0), tracking measurements (resolution ~ 40 μm)

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

ATLAS & LHCf

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm1 detector Arm2 detector

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Expected results @ 14 TeV collisions

 n 0

Energy spectra and transverse momentum distribution of:

  • photons (E > 100 GeV): E/E < 5%
  • neutral pions (E > 500 GeV): E/E < 3%
  • neutrons (E > few 100 GeV): E/E ~ 30%

in the pseudo-rapidity range  > 8.4

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

With Stable Beam at 900 GeV

Total of 42 hours for physics ~ 105 showers events in Arm1+Arm2

With Stable Beam at 7 TeV

Total of 150 hours for physics with different setups

Different vertical position to increase the accessible kinematical range Runs with or without beam crossing angle

~ 4·108 shower events in Arm1+Arm2 ~ 106 0 events in Arm1+Arm2

Status

Completed program for 900 GeV and 7 TeV

Removed detectors from tunnel in July 2010 Post-calibration beam test in October 2010

Upgrade to more rad-hard detectors to operate at 14 TeV in 2013

Summary of operations in 2009 and 2010

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

TeV  rays not from Crab but… …underground!

X Transverse projection Y Transverse projection Longitudinal projections

A2 25mm A2 32mm A2 25mm A2 32mm

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

L90% @ 40 mm cal.

  • f Arm1
  • MC (QGSJET2)
  • data

Thick for E.M. interaction (44X0) Thin for hadronic interaction(1.7)

Definition

  • f L90%

-ray like hadron like

  • L90% is the longitudinal position containing 90%
  • f the shower energy
  • PID study is still ongoing (use of neural

networks is under investigation)

Particle identification

Typical transition curve for  rays Typical transition curve for hadrons

Selection of  rays: L90% < 16 X0 + 0.002 x ΣEr

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm1 Arm2

gamma-ray like hadron like

Acceptance is different for the two arms. Spectra are normalized by # of -ray and hadron like events. Response for hadrons and systematic errors are under study.

Energy spectra at 900 GeV

Only statistical errors are shown

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm1 Arm2

gamma-ray like hadron like

Very high statistics: only 2% of data is shown here. Comparison with MC is under development

Energy spectra at 7 TeV

Only statistical errors are shown

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Energy spectrum (Arm2) An example of event (Arm2)

  • 0s 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 calibration

25mm 32mm

Silicon strip - X view

M/M = 2.3%

Reconstructed mass (Arm2)

m 140 = R 

I.P.1

 1(E1)

2(E2) 140m R

Neutral pions

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

2 invariant mass spectrum @ 7 TeV

0 candidates  candidates

  • The search for  particles is an important tool for discriminating hadronic

interaction models, because their spectra differ from model to model

  • Important tool also for energy scale calibration
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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

7 TeV 10 TeV 14 TeV

SIBYLL

7 TeV 10 TeV 14 TeV

  • 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

14 TeV in 2013: not only the highest energy, but energy dependence too!

QGSJET2

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Schedule and future plan

2010, Oct Beam test at SPS to confirm the radiation damage and the performance end of 2010 Finalize analysis at 900 GeV (almost completed) and at 7 TeV 2011 - 2012 Upgrade the detector for radiation hardness: replacement of scintillators and SciFi with GSO 2013 Re-installation of detectors in the tunnel for

  • peration at 14 TeV

Then we are thinking about:

  • Operation at LHC light ion collisions (not Pb-Pb).
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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

  • LHCf is a forward experiment at LHC; its aim is to measure energy

spectra and transverse momentum distributions of very energetic neutral secondaries from p-p interactions in the very forward region

  • f IP1 (at  > 8.4)
  • Results will help calibrating the hadronic interaction models; one

important field where this measurements are mostly important is the study of atmospheric showers induced by HECR

  • LHCf successfully completed operations at 900 GeV and at 7 TeV;

the detectors have been removed from the LHC tunnel on 21st July 2010

  • Analysis of data at 900 GeV is almost completed; we will finalize

analysis at 7 TeV before the end of this year

  • Detectors will be upgraded in 2011-2012 for

radiation hardness and will be re-installed for data taking at 7 TeV + 7 TeV in 2013

Conclusions

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Backup

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

AGASA Systematics Total ±18% Hadr Model ~10% (Takeda et al., 2003)

Open Issues on UHECR spectrum

M Nagano

New Journal of Physics 11 (2009) 065012

Depth of the max of the shower Xmax in the atmosphere

AUGER HiRes

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η ∞

8.7

Shadow of beam pipes between IP and TAN

IP1,ATLAS

Arm1 Arm2

Transverse projection of Arm#1

∞

8.4

@ zero crossing angle @ 140mrad crossing angle

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Detector vertical position and acceptance

Remotely changed by a manipulator( with accuracy of 50 mm)

Distance from neutral center Beam pipe aperture Data taking mode with different position to cover PT 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 thus enlarging Pt acceptance

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

LHCf single  geometrical acceptance

Mechanical manipulators allows to remotely move LHCf: some runs with the detectors vertically shifted few cm allow to cover the whole kinematical range

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

140

Beam crossing angle

LHCf acceptance on PT-E  plane

A vertical beam crossing angle > 0 increases the acceptance of LHCf

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Front counters

  • Thin scintillators with 8x8cm2 acceptance,

which have been installed in front of each main detector.

  • To monitor beam condition.
  • For background rejection of

beam-residual gas collisions by coincidence analysis

Schematic view of Front counter

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Beam-gas backgroud @ 900 GeV

2009 2010

Very big reduction in the Beam Gas contribution!!! Beam gas  I, while interactions  I2

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Comparison of Arm1 and Arm2 @ 7 TeV

Red : Arm1 Blue : Arm2 Same runs, same conditions, common rapidity region selected. Spectra corrected for the live time of detectors.

preliminary preliminary

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Selection of rapidity region (comparison Arm1/2)

R1=5mm R2-1 = 35mm R2-2 = 42mm theta = 20˚ Both Arm1 and Arm2 cover the same rapidity area in small and large tower. Here the beam center is determined by our measurements.

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

LHCf energy resolution

2.5 x 2.5 cm2 tower 2.0 x 2.0 cm2 tower

Energy resolution < 5% at high energy, even for the smallest tower

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm1 position resolution

Number of event Number of event x-pos[mm] y-pos[mm]

200 GeV electrons

E[GeV] E[GeV]

σX=172µm σY=159µm

σX[mm] σY[mm]

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Arm2 position resolution

Position Resolution X Side

20 40 60 80 100 120 50 100 150 200 250 Energy (GeV) Resolution (microns) Data Simulation Spread Out

Position Resolution Y Side

20 40 60 80 100 120 140 160 50 100 150 200 250 Energy (GeV) Resolution (microns) Data Simulation Spread Out

x-pos[mm] y-pos[mm]

Alignment has been taken into account

200 GeV electrons

E[GeV] E[GeV]

σX=40µm σY=64µm

σX[µm] σY[µm]

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

(Arm1 prototype) correction

2 mm

Leakage Correction

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

Radiation damage studies

30 kGy

  • Dose evaluation on the basis
  • f LHC reports on radiation

environment at IP1

  • ~ 100 Gy/day @ 1030 cm-2s-1

luminosity are expected

  • ~ 10 kGy during few months
  • peration lead to ~ 50% light
  • utput decrease
  • continuous laser calibration

to monitor scintillators and correct for the decrease of light output

  • test of Scintillating fibers and scintillators
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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

108 events! LHCf removal

Accumulated Events in 2010

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

LHCf Arm1 – installation

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Massimo Bongi – CRLHC Workshop – 29th November 2010 – ECT* Trento

LHCf Arm2 – installation

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LHCf data taking

The LHCf control room in the ATLAS area