Transcript Seminario LHCf Perugia - Istituto Nazionale di Fisica Nucleare

Perugia, 17 Dicembre 2009
LHCf:
un esperimento per la fisica
dei raggi cosmici ad LHC
Oscar Adriani
Università degli Studi di Firenze
INFN Sezione di Firenze
The LHCf Collaboration
USA
LBNL Berkeley:
W. Turner
CERN
D.Macina, A.L. Perrot
FRANCE
Ecole Politechnique Paris:
M. Haguenauer
SPAIN
IFIC Valencia:
A.Fauss, J.Velasco
ITALY
Firenze University and INFN:
O.Adriani,, L.Bonechi, M.Bongi,
G.Castellini, R.D’Alessandro,
P.Papini
Catania University and INFN:
A.Tricomi
JAPAN:
STE Laboratory Nagoya University:
Y.Itow, T.Mase, K.Masuda, Y.
Matsubara,H.Matsumoto,H.Menjo,
Y.Muraki,T.Sako,H. Watanabe
Shibaura University Saitama:
K.Kasahara
Kanagawa University Yokohama:
T.Tamura, K.Tanaka
Waseda University:Y.Shimizu,
Oscar Adriani Perugia,S.Torii
17/12/09
What is LHCf?
The Detectors
Oscar Adriani
Perugia, 17/12/09
LHCf: an Astroparticle Experiment at LHC
• LHCf is the smallest of the six
LHC experiments and is a fully
dedicated collider experiment
for HECR Physics
7TeV+ 7 TeV proton collisions at LHC
correspond to ELAB = 1017eV
• 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
Two independent electromagnetic calorimeters equipped with position
sensitive layers, on both sides of IP1 will measure energy and
position of g from p0 decays and neutrons produced in pp interaction
at LHC
Oscar Adriani Perugia, 17/12/09
Detector I
Tungsten
Scintillator
Scintillating fibers
Experimental set-up
INTERACTION POINT
IP1 (ATLAS)
140 m
Beam line
Detector II
Tungsten
Scintillator
Silicon mstrips
140 m
Detectors installed in the TAN region,
140 m away from the Interaction Point
1
Here the beam pipe splits in 2
separate tubes.
Charged particle are swept
away by magnets
 We cover up to y
Protons
Charged particles
Neutral particles
Beam pipe
Oscar Adriani
Perugia, 17/12/09
Absorber
22 tungsten layers
7mm – 14 mm thick
4 pairs of scintillating fiber
layers for tracking purpose
(6, 10, 32, 38 X0.)
(W: X0 = 3.5mm, RM = 9mm)
Arm1
16 scintillator layers
(3 mm thick)
Trigger and energy
profile measurements
2 towers 24 cm long stacked vertically with a 5 mm gap
Lower: 2 cm x 2 cm area
Upper: 4 cm x 4 cm area
Oscar Adriani
Perugia, 17/12/09
Arm2
Absorber
22 tungsten layers
7mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
4 pairs of silicon microstrip layers
(6, 10, 30, 42 X0) for tracking purpose
(X and Y directions)
16 scintillator layers
(3 mm thick)
Trigger and energy
profile measurements
2 towers 24 cm long stacked on their edges and offset from
one another
Lower: 2.5 cm x 2.5 cm
Upper: 3.2 cm x 3.2 cm
Oscar Adriani Perugia, 17/12/09
Transverse projection in TAN slot
ARM1: Maximization of the
acceptance for vertical beam
displacement (crossing
angle>0)
ARM2: Maximization of the
acceptance in R (distance
from beam center)
Oscar Adriani
Perugia, 17/12/09
The mechanics of the module
25 mm
Light Guides
+
Scintillators
Hybrid circuit
Pace Chips
Silicon sensor
SiliconX SiliconY
Kapton fanout
Tungsten
Oscar Adriani
Perugia, 17/12/09
Oscar Adriani
Perugia, 17/12/09
Silicon mstrips readout
Pace3 chips
(many thanks to CMS preshower!!!!)
•32 channels
•25 ns peaking time
•High dynamic range (> 400 MIP)
•192x32 analog pipeline
Oscar Adriani
Perugia, 17/12/09
Double ARM Detectors
Arm#1 Detector
Arm#2 Detector
Oscar Adriani
Perugia, 17/12/09
LHCf detectors in the LHC tunnel
Oscar Adriani
Perugia, 17/12/09
Why LHCf?
Physics Motivations
Oscar Adriani
Perugia, 17/12/09
Ultra High Energy Cosmic Rays
Extensive Air Showers
Experimental observations: at
E>100 TeV only EAS
(shower of secondary
particles)
• lateral distribution
• longitudinal distribution
• particle type
• arrival direction
Astrophysical parameters:
(primary particles)
• spectrum
• composition
• source distribution
• origin and propagation
Oscar Adriani
Perugia, 17/12/09
The Cosmic Ray Spectra
GZK cutoff: 1020eV
GZK cutoff would limit energy
to 1020eV for protons, due to
Cosmic Microwave
Background
pg(2.7K)DNp
super GZK
events?!?
Based on data
presented at the 30th ICRC
Merida (Mexico)
Figure prepared by Y. Tokanatsu
Different results
between different
experiments
Oscar Adriani
Perugia, 17/12/09
The Cosmic Ray Spectra
Berezinsky 2007
AGASA x 0.9
HiResx 1.2
Yakutsk x 0.75
Auger
x 1.2
Difference in the energy scale
between different
experiments???
Oscar Adriani
Perugia, 17/12/09
HECR composition
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
LHC
Unger, ECRS 2008
Oscar Adriani
Perugia, 17/12/09
HECR composition
Auger
Xmax measurements
favors heavier
composition as the
energy increases
Anisotropy would
favor proton
primaries (AGN
correlation still
valid?)
Oscar Adriani
Perugia, 17/12/09
Modelling Cosmic Rays at LHC
LHC
Nuclear Interaction
Astrophysical parameters
Calibration with data of
- source type
Monte Carlo used in
- source distribution
Cosmic Ray Physics
- source spectrum
Forward Physics
- source composition
- cross section
- propagation
- particle spectra
(E, PT, q, h,Perugia,
XF) 17/12/09
Oscar Adriani
Development of atmospheric showers
Cosmic ray spectrum
Tevatron
LHC
Determination of E and mass of cosmic
rays depends on description of primary
UHE interaction
Hadronic MC’s need tuning with data
The dominant contribution to the energy
flux is in the very forward region (q 0)
In this forward region the highest energy
available measurements of p0 cross section
done by UA7 (E=1014eV, y= 5÷7)
A 100 PeV fixed-target
interaction with air has the cm
energy of a pp collision at the
LHC
AUGER
LHCf: use LHC
√s = 14 TeVElab=1017eV
AlessiaTricomi
to calibrate MCs
University and INFN
Oscar Adriani
Catania
Perugia, 17/12/09
How LHCf can calibrate MC?
Physics Perfomances
Oscar Adriani
Perugia, 17/12/09
LHCf: acceptance on PTg-Eg plane
140
Beam crossing
angle
A vertical beam crossing angle > 0 willAlessia Tricomi
University and INFN
Catania
Adriani Perugia, 17/12/09
increase the acceptance Oscar
of LHCf
EPS 09, Krakow 16-22 July 2009
LHCf single g geometrical acceptance
Some runs with LHCf vertically shifted few cm
will allow to cover the whole kinematical range
Oscar Adriani
Perugia, 17/12/09
Energy resolution for g
For 20mm
For 40mm
5%
5%
Oscar Adriani
Perugia, 17/12/09
ARM2 Position Resolution
σy=64 mm
σx=40 mm
Number of event
Number of event
200 GeV electrons
x-pos[mm]
y-pos[mm]
Oscar Adriani
Perugia, 17/12/09
LHCf : Monte Carlo discrimination
106 generated LHC interactions 
1 minute exposure@1029 cm-2s-1 luminosity
Discrimination between various models is feasible
Quantitative
discrimination with
the help of a properly
defined c2
discriminating
variable based on
the spectrum shape
5% Energy resolution
Oscar Adriani
Perugia, 17/12/09
LHCf: model dependence of
neutron energy distribution
Original n energy
30% energy resolution
Oscar Adriani
Perugia, 17/12/09
g and n spectra at different energies
20 min @ 1029 cm-2s-1
1 min @ 1029 cm-2s-1
450 GeV
1 TeV
g
5 TeV
g
20 min @ 1029 cm-2s-1
1 min @ 1029 cm-2s-1
450 GeV
n
1 min @ 1029 cm-2s-1
1 TeV
n
g
1 min @ 1029 cm-2s-1
5 TeV
n
No detector resolution taken into account
Oscar Adriani
DPMJET3
QGSJET2
QGSJET1
SIBYLL
Perugia,
17/12/09
New Models
PICCO
EPOS
Drescher, Physical Review D77,
056003 (2008)
p0
Neutron
Oscar Adriani
Perugia, 17/12/09
p0
produced at collision can be extracted by using
gamma pair events
Powerful tool to calibrate the energy scale and also
to eliminate beam-gas BG
Gamma2
Gamma1
Emin
~
700GeV
Peak :
134MeV
Sigma:
4.9MeV
E2
E1
Geometrical Acceptance
p0 spectra
10mm Lower
Cut:
125-145MeV
Oscar Adriani
Perugia, 17/12/09
p0 spectra and model discrimination
 Reconstructed spectrum in good agreement with the
original π0 production spectrum (DPMJETⅢ)
 Systematic errors mainly due to the uncertainty of
the absolute energy scale of the calorimeters. ±5%
uncertainty were conservatively assumed
Oscar Adriani
Perugia, 17/12/09
p0 reconstruction at the SPS beam test
350 GeV Proton beam
g
Not in scale!
g
Carbon target (6 cm)
in the slot used for beam monitor
9.15 m
Arm1
>107 proton on target (special setting from the SPS people)
Dedicated trigger on both towers of the calorimeter
Calorimeters
Shower Profile @ First SciFi Layer
40mm
X
Egamma=18GeV
Y
20mm
Egamma=46GeV
X
Oscar Adriani
Y
Perugia, 17/12/09
p0 mass reconstruction
 250 p0 events triggered (in a quite big background)
 Main problems:
– low photon energy (≥20 GeV)
– Direct protons in the towers
The LHCf experiment at LHC
ISVHECRI08,
1-6in
September
– MultiParis
hits
the same tower
2008
(MeV)
Oscar Adriani
Perugia, 17/12/09
When LHCf?
NOW!!!!!!!!!!!
Oscar Adriani
Perugia, 17/12/09
2009 LHC Operation
• From End of October 2009 LHC restarted
operation
• 450 GeV + 450 GeV  1.2 TeV + 1.2 TeV
• Exceptional effort and success from LHC!!!
• Few weeks of ‘smooth’ running allowed LHCf
to collect some statistics at 450+450 GeV in
stable beam conditions (Moving from garage
to running position)    
• No stable beam at 1.2+1.2 TeV  No data at
this energy for this year 
Oscar Adriani
Perugia, 17/12/09
Run table for 2009 (Stable beam)
RUN
DATE
START
END
GAIN
#L2TA
Arm1
#L2TA
Arm2
BUNCH
02347
06/12/2009
23:17
00:25
Normal
65
86
4x4 (3*)
02349
08/12/2009
02:17
05:49
Normal
184
239
4x4 (3*)
02379
11/12/2009
02:06
02:43
Normal
102
103
5x5 (4*)
02380
11/12/2009
02:43
06:03
Normal
323
335
5x5 (4*)
02382
11/12/2009
07:34
10:34
Normal
335
411
5x5 (4*)
02387
11/12/2009
18:56
21:22
Normal
196
301
5x5 (3)
02391
12/12/2009
04:03
06:18
Normal
157
244
4x5? (2)
02393
12/12/2009
09:33
13:00
Normal
321
447
5x5 (3)
02395
12/12/2009
14:21
15:17
Normal
146
208
5x5 (3)
02396
12/12/2009
15:20
18:24
Normal
337
472
5x5 (3)
02399
12/12/2009
20:42
22:21
Normal
310
444
5x5 (3)
02412
15/12/2009
01:09
01:59
Normal
330
365
17x17?
(9+3*)
Number of detected showers > 6000!
Oscar Adriani
Perugia, 17/12/09
Arm1 g event
Oscar Adriani
Perugia, 17/12/09
Arm2 g event
Oscar Adriani
Perugia, 17/12/09
Arm2 neutron event
Transition curve in the calorimetric towers
is used to discriminate between g and n
L90%<20 X0
Oscar Adriani
Perugia, 17/12/09
PID
Neutrons
Photons
Oscar Adriani
Perugia, 17/12/09
Very preliminary first plots! Arm1
1. The Beam Pipe profile is clearly seen
2. Difference between Bunch Crossing
and single bunch clearly demonstrate
the evidence for collisions
Oscar Adriani
Perugia, 17/12/09
Arm2
Oscar Adriani
Perugia, 17/12/09
Which is the future of LHCf?
Oscar Adriani
Perugia, 17/12/09
Plans for the future
• At beginning of 2010, when LHC will restart,
we will take data
– 1.2+1.2 TeV
– 3.5+3.5 TeV
• When luminosity will become too high (>1031
cm-2s-1, 2 pb-1) we will go out from the TAN
(Radiation damage of the plastic scintillator
is significant, LHCf has been designed to run
at low luminosity/high energy!)
Oscar Adriani
Perugia, 17/12/09
Radiation Damage Studies
Scintillating fibers and scintillators
•Expected dose: 100 Gy/day at 1030 cm-2s-1
•Fewmonths @ 1030 cm-2s-1: 10 kGy
• 50% light output
•Continous monitor and calibrationwith
Laser system!!!
The LHCf experiment at LHC
ISVHECRI08, Paris 1-6 September
2008
Alessia Tricomi
30Catania
kGy
1 kGyUniversity & INFN
Oscar Adriani
Perugia, 17/12/09
Results on radiation damage
The dose approximately scale as E3
Energy
(TeV)
Dose rate
(Gy/hour at
1029cm-2s-1)
Dose rate
(Gy/nb-1)
Time to reach
1KGy at 1029cm-2s-1
(days)
Integrated
lumi to reach
1KGy (nb-1)
0.45+0.45
4.6•10-4
1.27•10-3
9140
7.9•105
3+3
1.3•10-1
0.35
330
2.9•103
5+5
6.1•10-1
1.7
68
590
7+7
1.6
4.3
27
230
Oscar Adriani
Perugia, 17/12/09
Energy flux in front of LHCf detector
Energy flux for 7TeV
3 orders of
magnitude
reduction in dose
from running to
garage positions
GeV/s/cm2
Oscar Adriani
Perugia, 17/12/09
Improve the radiation resistance of LHCf
Basic idea:
– Replace the plastic scintillator with more
RadHard scintillators
• GSO
– Rearrange the order of silicon sensors to improve
the silicon energy measurement
• Cross check for scintillator measurement
– Go back in the TAN for 5+5 TeV run at the end of
2010, after a beam test of the reassembled
detector to precisely calibrate it
• Removal when Luminosity will be too high
– Go back in the 20xx for 7+7 TeV run
Oscar Adriani
Perugia, 17/12/09
Energy Resolutions for g
Hit Position
Selection
4<x<20,
4<y<20
Good energy resolution of the silicon layers !!
Oscar Adriani
Perugia, 17/12/09
Conclusions
• LHCf is an interesting link between CR and
accelerators
• LHCf is ready for operation since 2007
• We got the first data just in these few weeks
• Detectors (and machine) are working very
fine
• Preliminary physics plots
• Increase statistics and c.m. energy in 2010
First spectra will be published soon!
Oscar Adriani
Perugia, 17/12/09
Emin
~
700GeV
p0 energy resolution
Geometrical Acceptance
Survival efficiency
3% @ 1TeV
10mm Lower
Oscar Adriani
Perugia, 17/12/09
Property of 2 candidates
• GSO
–
–
–
–
–
–
Emission; 440nm (peak)
Decay constant; 30-60ns
Rad hardness (definition to be checked); 106-7Gy
Laser; OK
Yield; 10,000 photons/MeV
Price; expensive! 700-800 CHF/piece
Advantage
Disadvantage
• PWO
–
–
–
–
–
–
–
–
Emission; 430nm (peak)
Decay constant; 2.1, 7.5, 26ns (3 components)
Rad hardness; 104-5Gy
Laser; to be tested
Yield; generally very small (to be tested)
Price; very cheap! 90CHF/piece
Limited <30mm (surveying other factory)
Temperature dependence?
• Some samples are already available in Nagoya and
being tested
Oscar Adriani
Perugia, 17/12/09
Uniformity of Sum(dE)
Map of sum(dE) of Scin.
Map of sum(dE) of Si
Y
X
Map(Si) / Map(Scin.)
The silicon layers have more dE than
scintillator layers due to additional dE by
particles leaking out from the calorimeters.
The difference increases near the top and
left edges.
Oscar Adriani
Perugia, 17/12/09