LHCF S

TATU

S AND

RESULTS

OS C A R

A DR

I AN

I ON

B E HA L F O

F T HE L H

C F C OL L A B O

R A T I ON

CERN, 23 MARCH 2011

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

HECR OPEN ISSUES

Difference in the energy scale between different experiments???

The depth of the maximum of the shower Xmax depends on energy and type of the primary particle

AGASA x 0.9AUGER x 1.3

Different hadronic interaction models give different answers about the composition of HECR

M NaganoNew Journal of Physics 11 (2009) 065012

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

Detectors installed in the TAN region, 140 m away from ATLAS Interaction Point (IP1)

Charged particles

Neutral particles

Beam pipe

Protons

LHCF EXPERIMENTAL SET-UP

Here the beam pipe splits in 2 separate tubes. Charged particle are swept away by magnets We will cover |h|>8

Front Counters: thin scintillators with 8x8cm2 acceptance installed in front of each main detector

ARM1 & ARM2 DETECTORSARM1

2 towers 24 cm long

stacked vertically

with 5 mm gap

Lower: 2 cm x 2 cm

areaUpper: 4 cm x 4 cm

area

Arm#190mm

290mm

Arm#2

O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1

ARM22 towers 24 cm long stacked on their edges and offset from one anotherLower: 2.5 cm x 2.5 cmUpper: 3.2 cm x 3.2 cm

16 scintillator layers (3 mm thick)Trigger and energy profile measurements

Energy

Impact point (h)

4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 r.l.)

4 pairs of silicon microstrip layers (6, 12, 30, 42 r.l.) for tracking purpose (X and Y directions) Absorber

22 tungsten layers 7– 14 mm thick (2-4 r.l.) (W: X0 = 3.5mm, RM = 9mm)

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

INCLUSIVE P

HOTON

SPECTR

UM ANALYSIS

L H C F DA T A T

A K I NG

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

LHCF OPERATIONS @900 GEV & 7 TEV

With Stable Beam at 900 GeV Dec 6th – Dec 15th 2009With Stable Beam at 900 GeV May 2nd – May 27th 2010

With Stable Beam at 7 TeV March 30th - July 19th

We took data with and without 100 μrad crossing angle for different vertical detector positions

Shower Gamma Hadron π0

Arm1 172,263,255 56,846,874 111,971,115 344,526

Arm2 160,587,306 52,993,810 104,381,748 676,157

Shower Gamma Hadron

Arm1 46,800 4,100 11,527

Arm2 66,700 6,158 26,094

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

DATA SET FOR INCLUSIVE PHOTON SPECTRUM ANALYSIS• Data–Date : 15 May 2010 17:45-21:23 (Fill Number : 1104) except runs during the luminosity scan. –Luminosity : (6.5-6.3)x1028cm-2s-1,–DAQ Live Time : 85.7% for Arm1, 67.0% for Arm2–Integrated Luminosity : 0.68 nb-1 for Arm1, 0.53nb-1 for Arm2 –Number of triggers : 2,916,496 events for Arm1

3,072,691 events for Arm2 –Detectors in nominal positions and Normal Gain• Monte Carlo–QGSJET II-03, DPMJET 3.04, SYBILL 2.1, EPOS 1.99 and PYTHIA8.145: about 107 pp inelastic collisions each LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

1 TEV p0 CANDIDATE EVENT

A p0 candidate event599GeV gamma-ray and 419GeV gamma-ray in 25mm and 32mm tower respectively.

LHCf Status Report

Longitudinal profile

Transverse profile

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

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

VDM scan

BCNWG paperhttps://lpc-afs.web.cern.ch/lpc-afs/tmp/note1_v4_lines.pdf

Beam sizes sx and sy measured directly by LHCf

LHCf Status Report

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

PARTIC

LE

IDENTIF

ICATION

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

•QGSJET2-gamma and -hadron are normalized to data(/collision) independently• LPM effects are switched on

Particle IdentificationPID criteria based on transition curve

500 GeV <EREC<1 TeV

MC/Data comparison done in many energy bins

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

PID CORRECTIONEfficiency and purity for gamma-ray estimated from L90% fitting with MC template (QGSJET2).

Hatched : data Red : true-gamma Blue : true-hadron Green : Red+BlueBin by bin (energy) correction applied to take into account shape disagreement between Data/MC (see systematic error section)

LHCf Status Report

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

ENER

GY SCALE IS

SUE

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

p0 MASS Arm1 Data

Peak at 145.8 ± 0.1 MeV

• Disagreement in the peak position• No ‘hand made correction’ is applied for safety• Main source of systematic error see later

Arm2 Data

Arm2 MC(QGSJET2)

Peak at 140.0 ± 0.1 MeV

Peak at 135.0 ± 0.2 MeV3.8 % shift

Many systematic checks have been done to understand the energy scale difference

LHCf Status Report

7.8 % shift

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

p0 MASS VS p0 ENERGY

Arm2 DataNo strong energy dependence of reconstructed mass

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

h MASS Arm2 detector, all runs with zero crossing angleTrue h Mass: 547.9 MeVMC Reconstructed h Mass peak: 548.5 ± 1.0 MeVData Reconstructed h Mass peak: 562.2 ± 1.8 MeV (2.6% shift)

LHCf Status Report

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

MULTI HIT

REJECTIO

N

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

MULTI-HIT REJECTIONIn order to extract inclusive single gamma spectra, rejection of multi-hit events is mandatory especially at high energy (> 2.5 TeV)

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

MULTI-HIT REJECTIONMulti-hit events are identified thanks to position sensitive layers in ARM1 (SciFi) and Arm2 (Si-mstrip)

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

MULTI-HIT REJECTION

LHCf Status Report

Single gamma detection efficiency for various MC models

Multi gamma detection efficiency for various MC models

Please have a look to systematic error section!

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

RESULTS

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

ACCEPTANCE CUT

R1 = 5mmR2-1 = 35mmR2-2 = 42mmq = 20o

For Small Tower h > 10.94 For Large Tower8.81 < h < 8.99

We define in each tower a region common both to Arm1 and Arm2, to compare the Arm1 and Arm2 reconstructed spectra.

Our final results will be two spectra, one for each acceptance region, obtained by properly weighting the Arm1 and Arm2 spectra

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

ARM1 AND ARM2 COMPARISON

- Multi-hit rejection and PID correction applied- Energy scale systematic not considered due to strong correlation between Arm1 and Arm2

Deviation in small tower: still unclear, but within systematic errors

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

COMBINED SPECTRA AND COMPARISON WITH MODELS

Arm1 and Arm2 combined spectra including syst. errors

Gray hatched:stat.+syst. errorBlue hatched:QGSJET2 stat. error

LHCf Status Report

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

SYSTEMATIC

UNCERTA

INTIES

E N E R G Y S C A L E , M U L T I - H I T , B E A M C E N T E R , P I D , L U M I N O S I T Y

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

SYSTEMATIC UNCERTAINTIES

Uncorrelated uncertainties between ARM1 and ARM2- Energy scale (except p0 error)- Beam center position- PID- Multi-hit selection

Correlated uncertainty- Energy scale (p0 error)- Luminosity error

Estimated for Arm1 and Arm2 by same methods but independently

Estimated by Arm2, and apply it to the both Arm

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

SYSTEMATIC ERROR FROM ENERGY SCALE

Two components:- Relatively well known: Detector response, SPS => 3.5%- Unknown: p0 mass => 7.8%, 3.8% for Arm1 and Arm2.

Please note: - 3.5% is symmetric around measured energy

- 7.8% (3.8%) are asymmetric, because of the p0

mass shift- No ‘hand made’ correction is applied up to now for safety

Total uncertainty is -9.8% / +1.8% for Arm1 -6.6% / +2.2% for Arm2

Systematic Uncertainty on Spectra is estimated from difference between normal spectra and energy shifted spectra.

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

BEAM CENTER POSITIONError of beam center position is estimated to be 1 mm from comparison between our results and the BPM results The systematic errors on spectra were estimated from the difference between spectra with 1 mm shift of acceptance cut area. (Small tower, true single-gamma) (Large tower, true single-gamma)

Fluctuation in HE is probably statistical

100 GeV<E<3.5 TeV : 5%

100 GeV<E<2.5 TeV : 10%E>2.5 TeV : 20%

Arm1 Results

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

SYSTEMATIC ERROR FROM PID

Template fitting A: 1 degree of freedom: - Absolute normalization

Template fitting B: 3 degrees of freedom: - Absolute normalization - Shift of L90% distribution - Width of L90% distribution

Efficiency and purity are estimated with two different approaches

Hatched : dataRed : true-gammaBlue : true-hadronGreen : Red+Blue

Systematic error from PID:100GeV<E<1.7TeV : 5%1.7TeV<E : 20%Both on small and large tower

Arm1

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

SYSTEMATIC ERROR FROM MHSystematic error is estimated from the deformation factor of original MC spectrum wrt reconstructed MC spectrum for various models

LHCf Status Report

True

/Rec

onst

ruct

ed

True

/Rec

onst

ruct

ed

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

CONCLUSIONS• LHCf Inclusive photon analysis has been completed

• Many detailed systematic checks were necessary!• ‘Very safe’ estimation of systematics• First comparison of variuos hadronic interaction models with

experimental data in the most challenging phase space region (8.81 < h < 8.99, h > 10.94)

• Other analysis are in progress (hadrons, PT distributions, different h coverage etc.)

• We are upgrading the detectors to improve their radiation hardness (GSO scintillators)

• Discussion are under way to come back in the TAN for the possible p-Pb run in 2013 (LHCC, Alice, LHC, Atlas etc.)

• We will anyway come back for the 14 TeV run with upgraded detector!!!!

LHCf Status Report

O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1

A SPECIAL THOUGHT FOR JAPAN

O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1

BACK-UP SLID

ES

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

⇔ΔXmax (DPMJETⅢ-QGSJETⅡ) = 36g/cm2

Transition curve for 1017eV proton

π0 reconstructed spectrum

Xmax = 696.6g/cm2 ± 2.3 +15.9, -7.8　 g/cm2

statisticalsystematic

IMPACT OF LHCF ON CR PHYSICS

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

LUMINOSITY DURING THE VDM SCANS

Fill 1059 (26th April)

Fill 1089 (09th May)

beam1 8.98±0.34 N(1)10.20±0.38 N(17851)

18.99±0.54 N(1)19.08±0.54 N(17851)

beam2 10.35±0.37 N(1)10.35±0.37 N(8911)

22.18±0.61 N(1)21.21±0.59 N(8911)

beam1*2 92.94 N(1) 421.20 N(1)

Luminosity (/cm2s)

FC1 2.01E+28FC2 2.00E+28FC1&2

2.09E+28

26th April 2010 9th May 2010Luminosity (/cm2s)

FC1 5.90E+27FC2 6.04E+27FC1&2

5.99E+27Intensity information

LHCf Status Report

O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1

LUMINOSITY ERRORS

contents errorIntensity2 5.0%Difference between April scan & May scan 2.1%Difference between arm1&2 2.7%Total 6.1%

Total systematic uncertainty due to luminosity was estimated to be 6.1%

LHCf Status Report

O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1

ESTIMATION OF PILE UPWhen the circulated bunch is 1x1, the probability of N collisions per Xing is

The ratio of the pile up event is

The maximum luminosity per bunch during runs used for the analysis is 2.3x1028cm-2s-1

So the probability of pile up is estimated to be 7.2% with σ of 71.5mbTaking into account the calorimeter acceptance (~0.03) only 0.2% of events have multi-hit due to pile-up. It does not affect our results

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

ENERGY RECONSTRUCTION AT SPSDifference of energy reconstruction at SPS between data and MC is < 1%.Systematic error for gain calibration factor layer by layer is 2%

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

COMPARISON OF EJ260 AND GSO-PULSE SHAPE-• Response for the N2 (Nitrogen) LASER• pulse width is ~300ps （ fast enough）• EJ260 : ~12ns decay time• GSO : 30~40ns decay time• Roughly similar decay time

EJ260

GSO

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

COMPARISON OF EJ260 AND GSO-RADIATION HARDNESS-

• EJ260 (HIMAC* Carbon beam)10% decrease of light yield after exposure of 100Gy

• GSO (HIMAC Carbon beam)No decrease of light yield even after 7*10^5Gy exposure,BUT increase of light yield is confirmed

• The increase depend on irradiation rate (~2.5%/[100Gy/hour])*HIMAC : Heavy Ion Medical Accelerator in Chiba

LHCf Status Report

O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1

LINEARITY OF PMT R7400• PMTs R7400 are used in current LHCf system• The test was held in HIMAC using Xe beam• PMT R7400 showed good linearity within 1% up to

signal level corresponding to 6TeV showerMAX in LHCf.

LHCf Status Report