Massimo Bongi - RESMDD08 - 15 October 2008 - Florence Massimo Bongi - INFN Florence LHCf...

Massimo Bongi - RESMDD08 - 15 October 2008 - Florence

Massimo Bongi - INFN Florence

LHCf Collaboration

Astroparticle Physics at LHC: the LHCf experiment ready

for data taking

7th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices

(RESMDD)

15-17 October 2008Florence


Overview

• Cosmic-Ray Physics goals– Ultra-High-Energy CR spectrum– composition of High-Energy CR(Monte Carlo codes calibration)

• LHCf detectors and experimental set-up• Physics performance• Current status


Ultra-High-Energy Cosmic Rays

Experimental observations:(shower of secondary particles)•lateral distribution•longitudinal distribution•particle type•arrival direction

Extensive Air Showers

Astrophysical parameters:(primary particles)•spectrum•composition•source distribution•origin and propagation

Air shower development (particle

interaction in the atmosphere)


UHECR spectra and the GZK cutoff

AGASAx 0.9HiRes x 1.2Yakutsk

x 0.75Auger x 1.2


UHECR spectra and the GZK cutoff

GZK cutoff would limit energy to 1020eV (for protons, due to Cosmic Microwave Background):

p + γ(2.7K) Δ N + π

Different hadronic interaction models give different answers for the primary CR energy estimate.

(for instance, AGASA reports 18% as systematic uncertainty in energy determination, 10% being due to the interaction model)

Calibration of models with experimental data


HECR composition

Energy(eV)

Xm

ax(g

/cm

2)

PROTON

IRON

UA7

The depth of the maximum of the

shower Xmax in the

atmosphere depends on energy

and type of the primary particle.

Different hadronic

interaction models give

different answers about

the composition of HECR.

LHCf


HECR composition

Auger Xmax measurements

favors heavier composition as the energy increases

Anisotropy would favor proton

primaries (AGN correlation)


Development of atmospheric showers

1019 eV proton

The dominant contribution to the shower development comes from particles emitted at low angles in the interaction of the primary CR (forward region).

The knowledge of the π-production cross-section in the forward region is needed in order to correctly estimate the energy of the primary CR.

The highest-energy data currently available are at 1014 eV (UA7@SppS, 1990)


Astroparticle Physics at LHC• LHCf will use the highest

energy particle accelerator to provide useful data to calibrate the hadronic interaction models used in Monte Carlo simulations of atmospheric showers.

• 7 TeV + 7 TeV proton collisions at LHC (ECM = 14 TeV)

correspond to ELAB = 1017 eV (ELAB ≈ ECM2/(2mp))


The LHCf Collaboration

ITALYITALYFirenze University and INFN:Firenze University and INFN: O.Adriani, L.Bonechi, O.Adriani, L.Bonechi, M.Bongi, G.Castellini, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini, S. R.D’Alessandro, P.Papini, S. Ricciarini, A. VicianiRicciarini, A. VicianiCatania University and Catania University and INFN:INFN: A.Tricomi A.Tricomi

JAPAN:JAPAN:STE Laboratory Nagoya University:STE Laboratory Nagoya University:K.Fukui,Y.Itow, T.Mase, K.Fukui,Y.Itow, T.Mase, K.Masuda,Y.Matsubara, K.Masuda,Y.Matsubara, H.Menjo,T.Sako, K.Taki, H. H.Menjo,T.Sako, K.Taki, H. WatanabeWatanabeWaseda University:Waseda University: K. Kasahara, M. K. Kasahara, M. Mizuishi, Y.Shimizu, S.ToriiMizuishi, Y.Shimizu, S.ToriiKonan University:Konan University: Y.Muraki Y.MurakiKanagawa University Yokohama: Kanagawa University Yokohama: T.TamuraT.TamuraShibaura Institute of Technology:Shibaura Institute of Technology: K. YoshidaK. Yoshida

SPAINSPAINIFIC Valencia:IFIC Valencia: A.Fauss, A.Fauss, J.VelascoJ.Velasco

FRANCEFRANCEEcole Politechnique Paris:Ecole Politechnique Paris:M. HaguenauerM. Haguenauer

USAUSALBNL Berkeley:LBNL Berkeley:W. TurnerW. Turner

CERNCERND.Macina, A.L. PerrotD.Macina, A.L. Perrot


The LHC ring

ATLAS (IP1)


Experimental set-up

INTERACTION POINTINTERACTION POINT

IP1 (ATLAS)IP1 (ATLAS)

Beam lineBeam line

Arm#2Arm#2

TungstenTungsten

ScintillatorScintillator

Silicon Silicon microstripsmicrostrips

Arm#1Arm#1

TungstenTungsten

ScintillatorScintillator

Scintillating Scintillating fibersfibers

140 m140 m 140 m140 m

Two independent electromagnetic calorimeters equipped with position sensitive layers, on both sides of IP1 will measure energy and position of γ from π0 decays.


Experimental set-up

96 mm

Charged particlesCharged particles

Neutral particlesNeutral particles

Beam pipeBeam pipe

ProtonsProtons

LHCf

• The detectors are installed in the TAN region, where the beam pipe

splits into 2 separate tubes.

• Charged particles are deflected away, only neutral particles hit the

detectors.


Arm#1 detector

Plastic Scintillator

16 layers 3 mm thick

trigger and energy profile measurements

Absorber

22 tungsten layers 7mm – 14 mm thick

(W: X0 = 3.5mm, RM = 9mm)

Scintillating Fibers

4 pairs of layers (6, 10, 32, 38 r.l.)

tracking measurements 2 towers stacked

vertically with 5 mm gap

24 cm long

upper: 4.0 cm x 4.0 cm

area

lower: 2.0 cm x 2.0 cm

area


Arm#2 detector

Plastic Scintillator

16 layers 3 mm thick

trigger and energy profile measurements

Silicon Microstrip (from ATLAS SCT)

4 pairs of layers (6, 12, 30, 42 r.l.)

tracking measurements 2 towers stacked on their

edges and offset from one

another

24 cm long

upper: 3.2 cm x 3.2 cm

area

lower: 2.5 cm x 2.5 cm

area

Absorber

22 tungsten layers 7mm – 14 mm thick

(W: X0 = 3.5mm, RM = 9mm)


Arm#1 detector Arm#2 detector

The detectors are ready since 2007


Front Counter• 2 Scintillator Counters

• installed in front of

Arm#1 and Arm#2

• segmented in 2 X and 2

Y slices

• check the beam quality,

reduce background

events and decide

whether to move Arm#1

and Arm#2 in the

operating position from

the “garage” position


LHCf Physics Single photon spectrum 0 mass reconstrucion (1 photon in each tower)

0 reconstruction is an important tool for energy calibration (0 invariant mass constraint)

Basic concept: • 2 towers for 0 reconstruction• Smallest tower on the beam (to reduce multiple hits)• Dimension of the tower Moliere radius• Maximum acceptance (given the LHC and TAN constraints)

Simulation has been used to understand the physics performances

Beam tests in 2004, 2006 and 2007, to evaluate: • energy resolution• spatial resolution of the tracking part


Detec

table

eve

nts

141400

Beam crossing angle

LHCf acceptance on PT-E plane

A vertical beam crossing angle > 0 will increase the acceptance of LHCf


LHCf single geometrical acceptance

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


LHCf : Monte Carlo discrimination

• 106 generated LHC interactions

• ~ min exposure @1029 cm-2s-1 luminosity

• already allows discrimination between various models (5% energy resolution included)


Neutron spectra at detector front 30% energy resolution included

LHCf: model dependence of neutron energy distribution


LHCf energy resolution

2.5 x 2.5 cm2 tower 2.0 x 2.0 cm2 tower

Energy resolution ~ 3% at high energy, even for the smallest tower


Pion reconstruction

9.15 m9.15 m

350 GeV Proton beam350 GeV Proton beam

Carbon target (3 cm)in the slot used for beam monitor Arm#1Arm#1

(not in scale)(not in scale)

Egamma=18GeV

Shower Profile @ First SciFi Layer Shower Profile @ First SciFi Layer Calorimeters Calorimeters

20mm

X

40mm

X Y

YEgamma=46GeV

>107 proton on target (special setting from the SPS people)


Pion mass reconstruction

(MeV)

Prelim

inary

250 pion events triggered (in a quite big background)

Δm ~ 8 MeVΔm/m ~ 6%


Arm#1 position resolutionN

um

ber

of

even

tN

um

ber

of

even

t

x-pos[mm]

y-pos[mm]

200 GeV electrons

E[GeV]

E[GeV]

σX=172µm

σY=159µmσ X

[mm

]σ Y

[mm

]


Arm#2 position resolutionPosition Resolution X Side

0

20

40

60

80

100

120

0 50 100 150 200 250

Energy (GeV)

Re

so

luti

on

(m

icro

ns

)

Data

Simulation Spread Out

x-pos[mm]

y-pos[mm]

Position Resolution Y Side

0

20

40

60

80

100

120

140

160

0 50 100 150 200 250

Energy (GeV)

Re

so

luti

on

(m

icro

ns

)

Data

Simulation Spread Out

Alignment has been taken into account

200 GeV electrons

E[GeV]

E[GeV]

σX=40µm

σY=64µmσ X

[µm

]σ Y

[µm

]


Radiation damage studies

30 kGy

Dose evaluation on the

basis of LHC reports on

radiation environment at

IP1

<10 Gy/day @ 1029 cm-2s-1

luminosity are expected

some tens Gy during 1

week operation lead to

~10% light output decrease

scintillators will be

monitored and decrease of

light output will be

corrected by laser

calibration

Silicon detectors from ATLAS SCT (see next

talk!) test of Scintillating fibers and scintillators


LHCf Arm#1 – Installation completed


LHCf Arm#2 – Installation completed


LHCf ready for data taking

The LHCf control room in the ATLAS area


Dummy event


LHCf ready for data taking• On September 10 we observed some signals on Front Counters, with

Arm#1 and Arm#2 in garage position for safety reasons

That day the Atlas BPTX signal was still not available (no info on

the real bunches in the Atlas zone)

• On September 11 Atlas gave us the synchronized BPTX signals, and

we could take Front Counter data by using this signal (still in garage

position)

• We are measuring beam-gas interactions from beam2 on Arm#1 side


LHCf ready for data taking


Detectors construction and installation completed in 2008

Preparation for running completed First beam gas events acquired We are ready for LHC data

Conclusions

Massimo Bongi - RESMDD08 - 15 October 2008 - Florence Massimo Bongi - INFN Florence LHCf...

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