1. LHCf: un esperimento per la fisica dei raggi cosmici ad LHC
Oscar Adriani
Università degli Studi di Firenze
INFN Sezione di Firenze

2. The LHCf Collaboration
CERN
D.Macina, A.L. Perrot
USA
LBNL Berkeley:
W. Turner
FRANCE
Ecole Politechnique Paris:
M. Haguenauer
SPAIN
IFIC Valencia:
A.Fauss, J.Velasco
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, S.Torii
ITALY
Firenze University and INFN: O.Adriani,, L.Bonechi, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini
Catania University and INFN: A.Tricomi
Oscar Adriani Perugia, 17/12/09

3. Oscar Adriani Perugia, 17/12/09
What is LHCf?
The Detectors
Oscar Adriani Perugia, 17/12/09

4. 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
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
7TeV+ 7 TeV proton collisions at LHC correspond to ELAB = 1017eV
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

5. Oscar Adriani Perugia, 17/12/09
Experimental set-up
INTERACTION POINT
IP1 (ATLAS)
Beam line
Detector II
Tungsten
Scintillator
Silicon mstrips
Detector I
Scintillating fibers
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
Charged particles
Neutral particles
Beam pipe
Protons
Oscar Adriani Perugia, 17/12/09

6. Arm1 2 towers 24 cm long stacked vertically with a 5 mm gap
4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 X0.)
Absorber
22 tungsten layers mm – 14 mm thick
(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

7. Arm2
4 pairs of silicon microstrip layers
(6, 10, 30, 42 X0) for tracking purpose (X and Y directions)
Absorber
22 tungsten layers mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
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

8. 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

9. The mechanics of the module
25 mm
Light Guides +
Scintillators
Hybrid circuit
Pace Chips
Silicon sensor
Kapton fanout
Tungsten
SiliconX SiliconY
Oscar Adriani Perugia, 17/12/09

10. Oscar Adriani Perugia, 17/12/09

11. 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

12. Oscar Adriani Perugia, 17/12/09
Double ARM Detectors
Arm#1 Detector
Arm#2 Detector
290mm
90mm
Oscar Adriani Perugia, 17/12/09

13. LHCf detectors in the LHC tunnel
Oscar Adriani Perugia, 17/12/09

14. Oscar Adriani Perugia, 17/12/09
Why LHCf?
Physics Motivations
Oscar Adriani Perugia, 17/12/09

15. Ultra High Energy Cosmic Rays
Experimental observations: at E>100 TeV only EAS
(shower of secondary particles)
lateral distribution
longitudinal distribution
particle type
arrival direction
Extensive Air Showers
Air shower development (particle interaction in the atmosphere)
Astrophysical parameters:
(primary particles)
spectrum
composition
source distribution
origin and propagation
Oscar Adriani Perugia, 17/12/09

16. 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?!?
Different results
between different
experiments
Based on data
presented at the 30th ICRC
Merida (Mexico)
Figure prepared by Y. Tokanatsu
Oscar Adriani Perugia, 17/12/09

17. Difference in the energy scale between different experiments???
The Cosmic Ray Spectra
AGASA x 0.9
HiResx 1.2
Yakutsk x 0.75
Auger x 1.2
Berezinsky 2007
AGASA Systematics
Total ±18%
Hadron interaction
(QGSJET, SIBYLL) ~10%
(Takeda et al., 2003)
Difference in the energy scale between different experiments???
Oscar Adriani Perugia, 17/12/09

18. 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
IRON
PROTON
Unger, ECRS 2008
IRON
LHC
Oscar Adriani Perugia, 17/12/09

19. 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

20. Modelling Cosmic Rays at LHC
Nuclear Interaction
Calibration with data of Monte Carlo used in Cosmic Ray Physics
Astrophysical parameters
- source type
- source distribution
- source spectrum
- source composition
- propagation
Forward Physics
- cross section
- particle spectra
(E, PT, q, h, XF)
Oscar Adriani Perugia, 17/12/09

21. Development of atmospheric showers
LHC
Tevatron
A 100 PeV fixed-target interaction with air has the cm energy of a pp collision at the LHC
AUGER
Cosmic ray spectrum
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 ( 0)
In this forward region the highest energy available measurements of p0 cross section done by UA7 (E=1014eV, y= 5÷7)
LHCf: use LHC
√s = 14 TeVElab=1017eV
to calibrate MCs
AlessiaTricomi University and INFN Catania
Oscar Adriani Perugia, 17/12/09

22. How LHCf can calibrate MC?
Physics Perfomances
Oscar Adriani Perugia, 17/12/09

23. LHCf: acceptance on PTg-Eg plane
140
Beam crossing
angle
Detectable events
A vertical beam crossing angle > 0 will
increase the acceptance of LHCf
EPS 09, Krakow July 2009
Alessia Tricomi University and INFN Catania
Oscar Adriani Perugia, 17/12/09

24. 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

25. Energy resolution for g
For 20mm
For 40mm 5% 5%
Oscar Adriani Perugia, 17/12/09

26. ARM2 Position Resolution
200 GeV electrons
Number of event
σy=64 mm
σx=40 mm
Number of event
x-pos[mm]
y-pos[mm]
Oscar Adriani Perugia, 17/12/09

27. LHCf : Monte Carlo discrimination
106 generated LHC interactions 
1 minute 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

28. LHCf: model dependence of neutron energy distribution
Original n energy
30% energy resolution
Oscar Adriani Perugia, 17/12/09

29. g and n spectra at different energies
cm-2s-1
cm-2s-1
cm-2s-1
450 GeV
1 TeV
5 TeV g g g
cm-2s-1
cm-2s-1
cm-2s-1
450 GeV
1 TeV
5 TeV n n n
DPMJET3
QGSJET2
QGSJET1
SIBYLL
No detector resolution taken into account
Oscar Adriani Perugia, 17/12/09

30. Oscar Adriani Perugia, 17/12/09
New Models
PICCO EPOS
Drescher, Physical Review D77,
(2008) p0
Neutron
Oscar Adriani Perugia, 17/12/09

31. Oscar Adriani Perugia, 17/12/09
p0 spectra E2 E1
Gamma2
Gamma1
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
Emin ~ 700GeV
Geometrical Acceptance
Peak :
134MeV
Sigma:
4.9MeV
Cut:
MeV
10mm Lower
Oscar Adriani Perugia, 17/12/09

32. 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
cm-2s-1
Oscar Adriani Perugia, 17/12/09

33. p0 reconstruction at the SPS beam testg
350 GeV Proton beam
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
Egamma=18GeV
Shower First SciFi Layer
Calorimeters
20mm X
40mm Y
Egamma=46GeV
Oscar Adriani Perugia, 17/12/09

34. Oscar Adriani Perugia, 17/12/09
p0 mass reconstruction
 250 p0 events triggered (in a quite big background)
(MeV)
Main problems:
low photon energy (≥20 GeV)
Direct protons in the towers
Multi hits in the same tower
The LHCf experiment at LHC ISVHECRI08, Paris 1-6 September 2008
Oscar Adriani Perugia, 17/12/09

35. Oscar Adriani Perugia, 17/12/09
When LHCf?
NOW!!!!!!!!!!!
Oscar Adriani Perugia, 17/12/09

36. Oscar Adriani Perugia, 17/12/09
2009 LHC Operation
From End of October 2009 LHC restarted operation
450 GeV GeV  1.2 TeV TeV
Exceptional effort and success from LHC!!!
Few weeks of ‘smooth’ running allowed LHCf to collect some statistics at GeV in stable beam conditions (Moving from garage to running position)    
No stable beam at TeV  No data at this energy for this year 
Oscar Adriani Perugia, 17/12/09

37. Run table for 2009 (Stable beam)
Number of detected showers > 6000!
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
184
239
02379
11/12/2009
02:06
02:43
102
103
5x5 (4*)
02380
06:03
323
335
02382
07:34
10:34
411
02387
18:56
21:22
196
301
5x5 (3)
02391
12/12/2009
04:03
06:18
157
244
4x5? (2)
02393
09:33
13:00
321
447
02395
14:21
15:17
146
208
02396
15:20
18:24
337
472
02399
20:42
22:21
310
444
02412
15/12/2009
01:09
01:59
330
365
17x17? (9+3*)
Oscar Adriani Perugia, 17/12/09

38. Oscar Adriani Perugia, 17/12/09
Arm1 g event
Oscar Adriani Perugia, 17/12/09

39. Oscar Adriani Perugia, 17/12/09
Arm2 g event
Oscar Adriani Perugia, 17/12/09

40. 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

41. Oscar Adriani Perugia, 17/12/09
PID
Photons
Neutrons
Oscar Adriani Perugia, 17/12/09

42. Very preliminary first plots! Arm1
The Beam Pipe profile is clearly seen
Difference between Bunch Crossing and single bunch clearly demonstrate the evidence for collisions
Oscar Adriani Perugia, 17/12/09

43. Oscar Adriani Perugia, 17/12/09
Arm2
--D: l’ombra e’ limitata alla parte in alto a destra (molto meno importante che per Arm1)
Oscar Adriani Perugia, 17/12/09

44. Which is the future of LHCf?
Oscar Adriani Perugia, 17/12/09

45. Oscar Adriani Perugia, 17/12/09
Plans for the future
At beginning of 2010, when LHC will restart, we will take data
TeV
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

46. Radiation Damage Studies
Scintillating fibers and scintillators
Expected dose: 100 Gy/day at 1030 cm-2s-1
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
1 kGy
Alessia Tricomi University & INFN Catania
30 kGy
Oscar Adriani Perugia, 17/12/09

47. 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)
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

48. 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

49. 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

50. 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

51. 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

52. Oscar Adriani Perugia, 17/12/09
Survival efficiency
p0 energy resolution
Emin ~ 700GeV
Geometrical Acceptance
1TeV
10mm Lower
Oscar Adriani Perugia, 17/12/09

53. 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! CHF/piece
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
Advantage
Disadvantage
Oscar Adriani Perugia, 17/12/09

54. Oscar Adriani Perugia, 17/12/09
Uniformity of Sum(dE)
Map of sum(dE) of Scin.
Map of sum(dE) of Si X Y
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