LHC forward experiment : LHCf

LHC forward experiment : LHCf Hiroaki MENJO
(KMI, Nagoya University, Japan)
On behalf of the LHCf collaboration
HESZ2013, Nagoya Univ., Japan, 02 -04 March
Contents
Large Hadron Collider
q  Introduction
q  The
-The most powerful accelerator on the earth-
LHCf experiment
-An LHC forward experimentq  Recent
results
Ultra High Energy Cosmic Rays
What is the most powerful accelerator in the Universe ?
-  Forward photon energy spectra
at 900GeV and 7TeV p-p
-  Forward π0 spectra
q  Recent
& Future Operation
q  Summary
SppS
Tevatron
LHC
The LHCf collaboration
T.Iso, Y.Itow, K.Kawade, Y.Makino, K.Masuda, Y.Matsubara,
E.Matsubayashi, G.Mitsuka, Y.Muraki, T.Sako
Solar-Terrestrial Environment Laboratory, Nagoya
University, Japan
Kobayashi-Maskawa Institute, Nagoya University, Japan
Shibaura Institute of Technology, Japan
H.Menjo
K.Yoshida
K.Kasahara, Y.Shimizu, T.Suzuki, S.Torii
Waseda University, Japan
Kanagawa University, Japan
Ecole Polytechnique, France
LBNL, Berkeley, USA
T.Tamura
M.Haguenauer
W.C.Turner
O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini,
S.Ricciarini, G.Castellini
K.Noda, A.Tricomi
J.Velasco, A.Faus
A-L.Perrot
INFN, Univ. di Firenze, Italy
INFN, Univ. di Catania, Italy
IFIC, Centro Mixto CSIC-UVEG, Spain
CERN, Switzerland
Introduction
HECRs
Extensive air shower observation
•  longitudinal distribution
•  lateral distribution
•  Arrival direction
Air shower development
Astrophysical parameters
•  Spectrum
•  Composition
•  Source distribution
Xmax distribution measured by AUGER
Xmax
the depth of air shower maximum.
An indicator of CR composition
Uncertainty of hadron interaction models
>
Error of <Xmax> measurement
1018
4 1019
Auger Coll. ICRC2011
① Inelastic cross section
If large σ
rapid development
If small σ
deep penetrating
④ 2ndary interactions
nucleon, π
② Forward energy spectrum
If softer
shallow development
If harder
deep penetrating
③ Inelasticity k= 1-plead/pbeam
If large k
(π0s carry more energy)
rapid development
If small k
( baryons carry more energy)
deep penetrating
5 (relevant to Nµ )
The Large Hadron Collider (LHC)
pp 7TeV+7TeV
è Elab = 1017eV
pp　3.5TeV+3.5TeV è Elab = 2.6x1016eV
pp 450GeV+450GeV è Elab = 2x1014eV
2014-
Key parameters
for air shower developments
q 
CMS/TOTEM
q 
q 
Total cross section
↔ TOTEM, ATLAS, CMS
Multiplicity
↔ Central detectors
Inelasticity/Secondary spectra
↔ Forward calorimeters
LHCf, ZDCs
ALICE
LHCb/MoEDAL
ATLAS/LHCf
6 The LHCf experiment
LHCf Detector(Arm#1)
ATLAS
Two independent detectors at either side of IP1 ( Arm#1, Arm#2 ) 140m Beam pipe
Protons
Charged particles (+)
Neutral particles
Charged particles (-)
96mm TAN -­‐Neutral Par-cle Absorber-­‐ transi-on from one common beam pipe to two pipes
7 Slot : 100mm(w) x 607mm(H) x 1000mm(T) The LHCf Detectors
Sampling and Positioning Calorimeters
•  W (44 r.l , 1.7λI ) and Scintillator x 16 Layers
•  4 positioning layers
XY-SciFi(Arm1) and XY-Silicon strip(Arm#2)
•  Each detector has two calorimeter towers,
which allow to reconstruct π0
Expected Performance
Energy resolution (> 100GeV)
< 5%
for photons
30% for neutrons
Position resolution
< 200µm (Arm#1)
40µm (Arm#2)
Arm2
32mm
25mm
Front Counter
•  thin scintillators with 80x80mm2
•  To monitor beam condition.
•  For background rejection of
beam-residual gas collisions
by coincidence analysis
40mm
20mm
8 Arm1
Arm1
Arm2
IP1,ATLAS
92mm
90mm
9 LHCf can measure
Front view of calorimeters
@ 100µrad crossing angle
Energy spectra and Transverse momentum distbu7on of •  Gamma-­‐rays (E>100GeV,dE/E<5%) •  Neutral Hadrons (E>a few 100 GeV, dE/E~30%) •  π0 (E>600GeV, dE/E<3%)
beam pipe shadow
8.5
∞
at pseudo-­‐rapidity range >8.4 Mul7plicity@14TeV η
Energy Flux @14TeV High energy flux !!
Low multiplicity !!
10 simulated by DPMJET3
Results from
√s = 900 GeV and
7 TeV p-p data
“ Measurement of zero degree single photon energy spectra
for √s = 7 TeV proton-proton collisions at LHC “
O. Adriani, et al., PLB, Vol.703-2, p.128-134 (09/2011)
“Measurement of zero degree inclusive photon energy spectra
for √s = 900 GeV proton-proton collisions at LHC“
O. Adriani, et al., Submitted to PLB.,CERN-PH-EP-2012-048
“Measurement of forward neutral pion transverse momentum spectra
for √s = 7TeV proton-proton collisions at LHC”
O. Adriani, et al., Submitted to PRD, arXiv:1205.4578
Operation in 2009-2010
At 450GeV+450GeV p-p
•  06 Dec. –15 Dec. in 2009
27.7 hours for physics, 2.6 hours for commissioning
~2,800 and ~3,700 shower events in Arm1 and Arm2
•  02 May – 27 May in 2010
~15 hours for physics
~44,000 and ~63,000 shower events in Arm1 and Arm2
At 3.5TeV+3.5TeV p-p
•  30 Mar. – 19 July in 2010
~ 150 hours for physics with several setup
With zero crossing angle and with 100µrad crossing angle.
~2x108 and ~2x108 shower events in Arm1 and Arm2
Operation at √s = 900GeV and 7TeV has been completed successfully.
The detectors has been removed from the LHC tunnels at July 2010,
and will be upgraded for the future operations.
12 Event sample
Longitudinal development measured by scintillator layers
25mm Tower
32mm Tower
è600GeV
è420GeV
photon
photon
Total Energy deposit
èEnergy
Shape
èPID
Lateral distribution measured by silicon detectors
X-view
Hit position,
Multi-hit search.
Y-view
π0 mass reconstruction from two photon.
M π 0 = Eγ 1Eγ 2 ⋅ θ
Systematic studies
Photon spectra at √s = 7 TeV p-p
LHCf Collaboration / Physics Letters B 703 (2011) 128–134
8.81<η<8.9
q 
q 
Pseudo-rapidity,
η>10.94 and 8.81<η<8.9
The spectra of two detectors are
consistent within the errors.
η>10.94
Arm1
Arm2
Fig. 1. Cross sections of the calorimeters seen from IP1, left for Arm1 and right for Arm2. The origin of the coordinates is defined as the zero degree collis
ideal case while the stars indicate the actual zero degree found in the experimental data. The shaded area over Y = 40 mm is behind the projection of th
case of 0 beam crossing angle where the calorimeters are insensitive to the collision products. Dashed lines in the calorimeters indicate the boarder of the
as described in Section 3.1 and the dark areas indicate common rapidity ranges of the two Arms selected to obtain the final spectra.
measure the neutral particle production cross sections at very forward collision angles of LHC proton–proton collisions, including
zero degrees. When the LHC reaches its designed goal of 14 TeV
collision energy, the energy in the equivalent laboratory frame will
be 1017 eV, a factor of one thousand increase compared to previous accelerator data in the very forward regions [8,9].
Two detectors, called Arm1 and Arm2, have been installed in
the instrumentation slots of the TANs (Target Neutral Absorbers)
located ±140 m from the ATLAS interaction point (IP1) and at
zero degree collision angle. Inside a TAN the beam vacuum chamber makes a Y shaped transition from a single common beam tube
facing the IP to two separate beam tubes joining to the arcs of
LHC. Charged particles from the IP are swept aside by the inner beam separation dipole D1 before reaching the TAN so only
neutral particles are incident on the LHCf detectors. This unique
location covers the pseudo-rapidity range from 8.7 (8.4 in case of
the operation with the maximum beam crossing angle) to infinity (zero degrees). Each detector has two sampling and imaging
calorimeters composed of 44 radiation lengths (1.55 hadron interaction lengths) of tungsten and 16 sampling layers of 3 mm
thick plastic scintillators. The transverse sizes of the calorimeters are 20 mm × 20 mm and 40 mm × 40 mm in Arm1, and
25 mm × 25 mm and 32 mm × 32 mm in Arm2. The smaller
calorimeters cover the zero degree collision angle. The cross sections of the calorimeters seen from IP1 are illustrated in Fig. 1.
Four X–Y layers of position sensitive detectors (scintillating fiber,
SciFi, belts in Arm1 and silicon micro-strip sensors in Arm2; 1 mm
and 0.16 mm readout pitches, respectively) are inserted in order
to provide transverse positions of the showers. The LHCf detec-
Arm1 detector
Arm2 detector
MC predictions of several hadron interaction models
and summarized in Section 6.
2. Data
Data used in this analysis was
√ obtained on 15 M
ing proton–proton collisions at s = 7 TeV with zero
crossing angle (LHC Fill 1104). The total luminosity
crossing bunches in this fill, L = (6.3–6.5) × 1028 cm
vided ideal operating conditions as discussed in Sectio
that were taken during a luminosity optimization scan
nated from the analysis. The trigger for LHCf events w
at three levels. The first level trigger (L1T) was gen
beam pickup signals (BPTX) when a bunch passed IP
trigger was generated when signals from any success
lation layers in any calorimeter exceeded a predefine
Then the second level trigger for shower events (L2TA
when the data acquisition system was armed. The th
chosen to achieve >99% efficiency for >100 GeV p
were recorded with the third level trigger (L3T) when
types of second level triggers (pedestal, laser calibratio
combined. Examples of the longitudinal and lateral de
electromagnetic showers observed in the Arm2 detect
in Fig. 2. In this case two electromagnetic showers fro
into two photons are shown, with each photon strik
ent calorimeter of the Arm2 detector. The generation
and L3T triggers, and hence the data recording, wer
independently for the Arm1 and Arm2 detectors. Dat
was carried out under 85.7% (Arm1) and 67.0% (Arm2)
Photon spectra at √s = 7 TeV p-p
Data
Sys.+Stat.
DPMJET 3.04
QGSJETII-03
SIBYLL 2.1
EPOS 1.99
PYTHIA 8.145
•  No model can reproduce the LHCf data perfectly.
•  DPMJET and PYTHIA are in good agreement Eγ<1.5TeV, but harder in E>1.5TeV.
•  QGSJET and SIBYLL shows reasonable agreement of shapes in high-η but not in low-η
•  EPOS has less η dependency against the LHCf data.
Photon spectra at √s = 900 GeV p-p
Data
Sys.+Stat.
MC/Data
DPMJET 3.04
QGSJETII-03
SIBYLL 2.1
EPOS 1.99
PYTHIA 8.145
•  Both of Data and MC show little η dependency.
•  The tendencies of MC against Data are very similar to one of 7 TeV in η > 10.94.
DATA : Comp. 900GeV/7TeV
Coverage of 900GeV and 7TeV
results in Feynman-X and PT
XF spectra : 900 GeV data vs. 7 TeV data
Preliminary
Arm1-Data
Preliminary
900GeV vs. 7TeV
with the same PT region
Data 2010 at √s=900GeV
(Normalized
number
Data 2010byatthe
√s=7TeV
of(η>10.94)
entries in XF > 0.1)
Data
2010
at √s=7TeV
(η>10.94)
Data
2010
at √s=900GeV
Small tower : 22.6%
Large tower : 77.4%
Scaling factor : 0.1
Good agreement of XF spectrum
shape between 900 GeV and 7TeV.
èweak dependence of <pT> on ECMS
Note : No systematic error is considered
in both collision energies. 21% of the luminosity
determination error allows vertical shift.
1
d
inel dXF
⇥<limited
/
i
• Good agreement of each XF scali
dependence of <pT> on ECMS.
π0 analysis
140m
θ
γ2(E2)
Eπ 0 = Eγ 1 + Eγ 2 ,
I.P.1
PT π 0 = PT γ 1 + PT γ 2
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
300
T
0.4
0.4
-4
10-4
0.3
0.3
100
0
80
10
E=E=
0.2
0.2 1T1eTe
VV
0.1
0.1
100
120
140
160
180
Reconstructed mγ γ [MeV/c2]
00
99
-3
eVV
2TTe
EE==2
0.4
0.4
-2
-3
-3
eV
2TTeV
E=2
E=
0.5
0.5
200
-2
-2
eV
3T eV
EE==3T
400 9.0 < y < 9.2
∫
Ldt=2.53nb
1
T
LHCf-Arm1 s=7TeV,
-1
p [GeV/c]
p T[GeV/c]
500
Acceptance
- PTfound. A chi-sq
tically
significantRapidity
difference was
1
1
of the corrected spectra
based on the default
10
0.9
LHCf
Arm1
LHCfensures
Arm2 the 10ch
function
true spectra
LHCf
Arm1against10 the 0.9
LHCf
Arm2
0.8than 60 %. Thus it is co
probability is greater
0.8
0.7 used in this analysis the
that with the method
0.7
10
significant bias and
the
0.6 statistical uncertainty is
10
10
0.6
quoted.
0.5
0.5
eV
3TeV
E=3T
E=
Events / (1 MeV/c2)
Mass reconstructed from photon pairs
pp [GeV/c]
T [GeV/c]
R
R
140 m
θ=
γ1(E1)
Mass, energy and transverse momentum are
reconstructed from the energies and impact
positions of photon pairs measured by each
calorimeter
M π 0 = Eγ 1 Eγ 2θ 2 ,
0.3
0.3
-4
10
-5
0.1
0.1
E.1010 Acceptance
correction
00
-5
-5
9.5
9.5
10
EE=
0.2 =1T1Te
0.2
eVV
10
10
10.5
11
10.5
11
Rapidity
Rapidity
99
9.5
9.5
1010
10.5
10.5 1111
Rapidity
Rapidity
Rapidity
10
Data 2010
10-2
-2
LHCf s=7TeV π0
9.2 < y < 9.4
1
∫ Ldt=2.53+1.90nb
-1
3
-1
3
10
∫ Ldt=2.53+1.90nb
-1
11
-1
10
3
-1
3
∫ Ldt=2.53+1.90nb
-1
LHCf s=7TeV π0
9.0 < y < 9.2
1
1/ σinel Ed σ/dp [GeV c3]
-2
LHCf s=7TeV π0
8.9 < y < 9.0
1
1/ σinel Ed σ/dp [GeV c3]
1/ σinel Ed3σ/dp3 [GeV-2c3]
π0 spectra at √s = 7 TeV p-p
10-2
10-2
DPMJET 3.04
QGSJET II-03
-3
-3
SIBYLL 2.1
10
-3
10
10
EPOS 1.99
PYTHIA 8.145
0.2
0.3
0.4
0.5
10-40
0.6
0.1
0.2
0.3
0.4
-1
∫ Ldt=2.53+1.90nb
-1
10-1
3
10-2
10-3
10-4
10-2
10-3
0
0.1
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
0.1
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
LHCf s=7TeV π0
10.0 < y < 11.0
1
∫ Ldt=2.53+1.90nb
-1
10-1
3
∫ Ldt=2.53+1.90nb
10-1
LHCf s=7TeV π0
9.6 < y < 10.0
1
3
-2
LHCf s=7TeV π0
9.4 < y < 9.6
1
10-40
0.6
pT [GeV/c]
1/ σinel Ed σ/dp [GeV c3]
1/ σinel Ed3σ/dp3 [GeV-2c3]
pT [GeV/c]
0.5
-2
0.1
3
10 0
1/ σinel Ed σ/dp [GeV c3]
-4
10-4
0
10-2
10-3
0.1
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
10-4
0
0.1
•  EPOS1.99 show the best agreement with data in the models.
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
FIG.• 7:DPMJET
(color online).
Combined
pT spectra
of harder
the Arm1 spectra
and Arm2 detectors
(black
dots) and themodel”)
total uncertainties (shaded
and
PYTHIA
have
than
data
(“popcorn
triangles) compared with the predicted spectra by hadronic interaction models.
•  QGSJET has softer spectrum than data. (only one quark exchange is allowed)
MC/Data
MC/Data
LHCf π0 PT spectra at 7TeV (data/MC)
DPMJET 3.04 QGSJETII-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145
EPOS gives the best agreement both for shape and yield.
0
PT[GeV]
0.6
0
0
PT[GeV]
0.6
0
PT[GeV]
20 PT[GeV]
0.6
0
PT[GeV]
0.6
0.6
0
PT[GeV]
0.6
<PT> of π0 at √s = 7 TeV p-p
pT spectra vs best-fit function
Average pT vs ylab
PLB 242 531 (1990)
YBeam=6.5 for SPS
YBeam=8.92 for7 TeV LHC
ylab = ybeam - y
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
Neutron analysis on-going
Big discrepancy
between models.
10000
9000
8000
7000
Small tower
true energy
MC
4000
PYTHIA
EPOS
QGSJET2
DPMJET3
SYBILL
(0% smeared)
@ 1.5TeV n
Detector performance
is also interaction
model dependent.
QGSJET2
DPMJET3
SYBILL
3000
true energy
Entries
Entries
5000
2000
4000
(0% smeared)
1500
3000
1000
2000
500
1000
0
0
10000
1000
2000
3000
4000
5000
6000
Energy[GeV]
Small tower
9000
PYTHIA
EPOS
8000
QGSJET2
DPMJET3
SYBILL
7000
35% smeared
6000
Entries
Performance
for neutrons
o  70% Efficiency
o  35% Eres
o  1mm Position Res.
PYTHIA
EPOS
3500
2500
6000
q 
Large tower
5000
4000
0
0
1000
2000
3000
4000
5000
6000
Energy[GeV]
Detector performance
Large tower
4000
PYTHIA
EPOS
3500
QGSJET2
DPMJET3
SYBILL
3000
2500
35% smeared
Entries
q 
2000
1500
3000
1000
2000
500
1000
0
0
1000
2000
3000
4000
5000
6000
Energy[GeV]
0
0
1000
2000
3000
4000
5000
6000
Energy[GeV]
Operation in 2013 and
future prospects.
Resent and Future operations
p-Pb operation (Jan-Feb. 2013)
Install the one of the LHCf detector.
Nuclear effect at the proton remnant side.
LOI, O.Adriani, et al.CERN-LHCC-2011-2015
p-p at 13TeV (2015)
Done
Future
Measurement at the LHC design energy.
Energy scaling by comparison with √s = 900 GeV and 7 TeV data
TDR, O.Adriani, et al. CERN-LHCC-2006-004
p-light ions (O, N) (2019?)
Collisions as high energy cosmic-rays and atmospheric nuclei.
Operations at RHIC ( Sako’s talk tomorrow)
Lower collision energy, ion collisions.
Starting discussion with RHIC people.
LHCf p – Pb runs at √sNN= 5 TeV
IP2
Pb
IP1
Arm2
p
IP8
l 2013 Jan-Feb for p-Pb/Pb-p collisions.
¡ Install only Arm2 at one side (Si good for multiplicity)
¡ Data both at p-side (20Jan-1Feb) and Pb-side (1fill, 4Feb)
One of the LHCf detector
(Arm2) has been installed
into the LHC tunnel again
in Dec. 2012.
Arm2 detector
25 LHCf p-Pb runs
L = 1x1029 – 0.5x1029cm-2s-1
q  β* =0.8m, 145µrad crossig angle
q  338p+338Pb bunches (min.ΔT=200ns), 296 colliding at IP1
q  10-20kHz trig rate downscaled to ~700Hz
q  20-40Hz ATLAS common trig. Coincidence seems successful
#Events (Millions) q 
Statistic in Operation 2013
p-­‐remnant side Pb-­‐remnant side Beam reversal 20 Jan 27 Jan. 01 Feb. 26 Operation at Pb-remnant side
Pb-remnant side
IP2
p
IP1
Arm2
Pb
IP8
+4.0MC
cm (Pb-remnant)
shift from beam spo
3.5cm,
4.0cm
A high multiplicity event (Pb-side)
27 Operations in 2013
Proton-Proton Collision at √s = 2.76 TeV.
o  4 hours operation on 14 Feb. 2013 successfully done.
è Energy Scaling by comparing with 7TeV and 900GeV data
q  CommonJoint
operation
with ATLAS in 2013
Data Taking
LHCf won't be in ATLAS readout (no ROD/ROB for LHCf)
o  ATLAS was triggered by prescaled LHCf triggers ( 20-40 Hz)
Strategy is to record events independently events and then merge them at
q 
offline level (cf https://edms.cern.ch/document/930829/1)
→ Write ATLAS LVL1ID in LHCf
event
よって生じているかを推定するのは容易ではない。
L1
Common analysis with ATLAS
LHCf検出器が設置されている衝突点（IP1）に
can help to study the mechanisms
は、ATLAS検出器が設置されている。ATLASと
of forward particle production.
LHCfによって広いラピディティ（η）領域をカバー
èCentral information.
L1ID etc...
した測定を行うことにより、陽子衝突事象の分類が
èZDC
可能になる。図３は、ATLASとLHCf検出器のラピ
ティティ範囲と特徴的な事象での生成粒子の分布を
示した。Diffractive事象では、中心領域には粒子生
L1_LHCf
Raw
Raw
成がなく、ATLAS検出器を使うことでNonDiffractive事象と明瞭に区別することができる。図
Merging
Reco
Reco
４には、ハドロン相互作用モデルEPOS1.99LHC4)を
用いて計算した14TeV陽子衝突での最前方中性子ス
Merged D3PD (?)
ペクトルを示す。中心領域 (¦η¦<5)に粒子生成がゼ
To have a substantial overlap between ATLAS and LHCf, ATLAS should
ロであり、高エネルギー陽子の有無により、Single/
record events when LHCf trigger
fires
Not clear at which level of data
format
will be merged
→ Useful to discuss 3
Double
Diffractive
事象選別したものを破線で示す。
with physics group and Data Preparation
Data list of LHCf
γ, n
π0
With ATLAS
p-­‐p, √s=900GeV, 2010 ✔ (event flags) p-­‐p, √s=2.76TeV, 2013 ✔ LHCf triggers è p-­‐p, √s=7TeV, 2010 ✔ ✔ (event flags) p-­‐p, √s=13 TeV, (2015) ✔ ✔ LHCf triggers è p-­‐N,O, (>2019) ✔ ✔ p-­‐Pb, √sNN=5TeV, 2013 ✔ ✔ LHCf triggers è p-­‐p 400GeV, p-­‐A at RHICH (???) ✔ ✔ è PHENIX, STAR Future
operations
LHCf triggers è Data list of LHCf
γ, n
p-­‐p, √s=900GeV, 2010 p-­‐p, √s=2.76TeV, 2013 p-­‐p, √s=7TeV, 2010 π0
With ATLAS
(event flags) Energy
- Energy Scaling
LHCf triggers è ✔ - Larger PT Coverage
✔ Higher
flags) ✔ PT = (√s/2)
✔ XF (event θ
p-­‐p, √s=13 TeV, (2015) ✔ p-­‐N,O, (>2019) ✔ p-­‐Pb, √sNN=5TeV, 2013 ✔ p-­‐p 400GeV, p-­‐A at RHICH (???) ✔ LHCf triggers è ✔ Heavier
Ion
- Nuclear effect
✔ LHCf triggers è ✔ LHCf triggers è Extend our Physics
-  Diffraction
✔ è PHENIX, STAR Summary
q 
q 
q 
q 
q 
LHCf has measured the energy and transverse momentum spectra
at the very forward region of √s = 900GeV and √s =7TeV p-p collisions
in 2010.
We showed the spectra of very forward photons at √s = 900 GeV and 7
TeV p-p collisions and π0s at √s = 7 TeV p-p collisions. No model can
produce data perfectly but the data are located in the middle of the
model predictions.
Many analyses are ongoing,
o  Hadron analysis
o  PT spectrum of photons
Recent and Future operations will provide many data.
o  p-Pb collisions (Successfully done in 2013)
o  p-p collisions at √s = 7TeV (2015)
o  p-Light ion (O,N) (>2019)
o  operations at RHIC
Analysis with the central data (ATLAS)
o  Trigger exchange between LHCf and ATLAS
Backup slides
ATLAS
Photos
620mm
η
8.7
∞
ne
is
x
a
m
a
e
utral b
Shadow of beam pipes
between IP and TAN
280mm 90mm
Pseudo-rapidity range.
η > 8.7 @ zero crossing angle
η > 8.4 @ 140urad
7TeV π0 analysis
7TeV photon spectra by LHCf
PT threshold
PT threshold
PT threshold
PT threshold
(Phys. Lett. B 703 128-134 (2011))
• 
Photon analysis and π0 analysis compensate each missing information.
- High energy photon originates from large PT π0 events.
- Photon spectrum includes a contribution from other hadrons/baryons.
Photon PT analysis can
connect each measuremen
Photons on the p-remnant side
Photon energy distrib. in different η intervals at √sNN = 7
TeV
q  Comparison of p-p / p-N / p-Pb
q  Enhancement of suppression for heavier nuclei case
q 
QGSJET II-04
SIBYLL 2.1
p-p
p-N
p-Pb
All ηs
8.81<η<8.99
η>10.94
Courtesy of S. Ostapchenk
35 Event sample
Longitudinal development measured by scintillator layers
25mm Tower
32mm Tower
è600GeV
è420GeV
photon
photon
Total Energy deposit
èEnergy
Shape
èPID
Lateral distribution measured by silicon detectors
X-view
Hit position,
Multi-hit search.
Y-view
π0 mass reconstruction from two photon.
M π 0 = Eγ 1Eγ 2 ⋅ θ
Systematic studies
900GeV photon analysis
Cross section of LHCf detectors
Beam pipe shadow
Arm1
Beam pipe shadow
Arm2
Two pseudo-rapidity ranges
•  - η>10.15
- 8.77<η<9.46
Arm1 and Arm2 data show
an overall good agreement
within their systematic uncertainties.
Arm1 data vs Arm2 data
4.5
4
3.5
3
LHCf s=7TeV π
0
DPMJET 3.04
QGSJET II-03
8.9 < y < 9.0
SIBYLL 2.1
∫ Ldt=2.53+1.90nb
-1
EPOS 1.99
5
4.5
4
3.5
PYTHIA 8.145
3
LHCf s=7TeV π
MC/Data
5
MC/Data
0
9.0 < y < 9.2
4.5
4
-1
3
2.5
2.5
2.5
2
2
2
1.5
1.5
1.5
1
1
1
0.5
0.5
0.5
0
0
0.1
0.2
0.3
0.4
0.5
0
0
0.6
0.1
0.2
0.3
0.4
pT [GeV/c]
5
4.5
4
3.5
3
LHCf s=7TeV π0
9.4 < y < 9.6
-1
0
0
0.6
5
LHCf s=7TeV π0
4.5
9.6 < y < 10.0
4
3.5
∫ Ldt=2.53+1.90nb
0.5
-1
2
1.5
1.5
1.5
1
1
1
0.5
0.5
0.5
0.6
pT [GeV/c]
0.3
0.4
0
0
0.1
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
0.5
0.6
LHCf s=7TeV π0
10.0 < y < 11.0
∫ Ldt=2.53+1.90nb
-1
3
2
0.5
0.2
4
2
0.4
0.1
3.5
∫ Ldt=2.53+1.90nb
3
0.3
-1
4.5
2.5
0.2
∫ Ldt=2.53+1.90nb
5
2.5
0.1
9.2 < y < 9.4
pT [GeV/c]
2.5
0
0
LHCf s=7TeV π0
pT [GeV/c]
MC/Data
MC/Data
5
3.5
∫ Ldt=2.53+1.90nb
MC/Data
MC/Data
12
0
0
0.1
0.2
0.3
0.4
0.5
0.6
pT [GeV/c]
G. 8: (color online). Ratio of the combined pT spectra of the Arm1 and Arm2 detectors to the predicted pT spectra by
dronic interaction models. Shaded areas indicate the range of total uncertainties of the combined pT spectra.