1. News da LHCf Oscar Adriani Università degli Studi di Firenze
INFN Sezione di Firenze

2. LHCf: detector overview
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
IP1 (ATLAS)
140 m
140 m
Beam line
44X0,
1.6 lint
Arm#1 Detector
20mmx20mm+40mmx40mm
4 SciFi tracking layers
Arm#2 Detector
25mmx25mm+32mmx32mm
4 Silicon strip tracking layers
Oscar Adriani Torino, 17/05/10

3. Oscar Adriani Torino, 17/05/10
Calibrate cosmic ray interactions for very forward energy spectra at LHC energy
Single g
Discriminate a good model
Input data for model building p0
neutron
Model difference in very forward at 14TeV
Oscar Adriani Torino, 17/05/10

4. Oscar Adriani Torino, 17/05/10
LHCf 2010 runs
Successful data taking at 7TeV collisions is ongoing.
Integrated Luminosity ~ 5.0 nb-1 up to May 16, 2010
~60M showers and 200K p0s obtained ( arm1+arm2 ).
Detector shows good performance with stable quality.
Energy scale calibration with the p0 peak.
Good stability < ±1% level. Yet no radiation problem.
Oscar Adriani Torino, 17/05/10

5. Statistic plot up to 16 May 2010
Red = Shower Arm1
Blue = p0 Arm1 (x100)
Light red=Shower Arm2
Light Blue = p0 Arm2 (x100)
Shower Trigger
g-like p0
Live time(*)
Arm1
29,515,720
8.0e6
59,000
96%
Arm2
33,230,720
1.0e7
140,000
93%
Oscar Adriani Torino, 17/05/10

6. Oscar Adriani Torino, 17/05/10
Arm1
7 TeV collisions
1 TeV gamma-ray Arm2
Transition curve in towers
Particle Hit maps
X-view of silicon strip
Arm2
Y-view of silicon strip
Oscar Adriani Torino, 17/05/10

7. Oscar Adriani Torino, 17/05/10
p0 at 7 TeV
Arm2 event display
Silicon layers
25 mm
tower
32 mm
tower
Scintillator layers
Robust sample
Good energy calibrator
32mm 25mm
Tower
Oscar Adriani Torino, 17/05/10

8. Oscar Adriani Torino, 17/05/10
Please note the very
high energy!!!!
DM/M=5.0MeV/135MeV=3.7%
Oscar Adriani Torino, 17/05/10

9. Oscar Adriani Torino, 17/05/10
DM/M=3.1MeV/135MeV=2.3%
Oscar Adriani Torino, 17/05/10

10. Quick look at 7TeV collisions (Arm2)
Colliding bunch
Non-colliding
bunch
High statistics !!
Only <1% of total data are used
Very clean data!!
BKG due to beam-gas
collisions is ~ 1%
Oscar Adriani Torino, 17/05/10

11. Oscar Adriani Torino, 17/05/10
Gamma/Hadron at 7 TeV
Arm1 Data
Small+Large
Small+Large
Gamma+Hadron
Gamma+Hadron
Oscar Adriani Torino, 17/05/10

12. Detector gain stability in Apr 2010
7TeV run
Laser gain calibration for scintillator layers
±2%
±1% level stability !
01/04
15/04
±2%
p0 mass peak
cumulative
dose
0.045Gy
Oscar Adriani Torino, 17/05/10

13. FrontCounter as a good luminosity monitor
Stay all the time
Beam pipe
TAN
Neutral
particles FC
LHCf-CAL
BRAN-Sci
ZDC
BRAN-IC
Page1
LHCf page
FC is working very well for luminosity monitoring (Very useful monitor for the machine)
Continuous monitoring w/ independent DAQ now available. See Page1 “LHCf experiment”
Conversion to “luminosity” from FC rate is now under study by MC
Gaussian fit
Arm1
Arm2
Coincidence
lumiscan
Oscar Adriani Torino, 17/05/10

14. Next Step for the analysis (in progress)
Understand where LHCf is wrt Beam!!!!
Crucial for the Pt spectra measurements
We are using/planning to use:
Survey measurements
Internal LHCf alignment
Position of the vertical manipulator
Beam spot position from Atlas (Many thanks!!!)
Reconstructed center of the neutral particle flux from LHCf position sensitive detectors
Caution: Beam crossing is not stable
Fill/Fill difference
Inside-fill difference
Oscar Adriani Torino, 17/05/10

15. Reconstruction of the beam center
X View
Make use of the silicon infos
Alghoritm optimized for online monitor
270 mm resolution
Y View
240 mm resolution
Oscar Adriani Torino, 17/05/10

16. E-q distribution for g-like shower at 7TeV
Measurement distribution of Arm2
(not corrected by geometrical acceptance)
Geometrical acceptance
Preliminary
Data : only first collisions (30/03/2010) ,000 shower trigger
Assumed the beam center is at (X,Y)=(3.0mm, 0.0mm).
Oscar Adriani Torino, 17/05/10

17. p0 PT Distribution at 7 TeV
Data : #fill 1058 (24/04/2010)
Assumed the beam center is at (X,Y)=(3.0mm, 0.0mm).
Measurement distribution without correction of geometrical acceptance
Oscar Adriani Torino, 17/05/10

18. Oscar Adriani Torino, 17/05/10
Analysis of 900GeV runs in 2009
Stable beams at 900GeV, 06.Dec. – 15.Dec (27.7 hours)
2,800 and 3,700 showers in Arm1 and Arm2, for ~5e5 collisions at IP1
Progress in Analysis since last LHCC
Refine analysis tools and fix final data sets for Dec09 run.
Absolute energy calibration by p0 peak at 7TeV
Expected spectra with each hadron interaction model
Gamma-ray Arm2
Hadron Arm2
with 107 col.
Oscar Adriani Torino, 17/05/10

19. Particle Identification
Clear discrimination between g and hadron showers based on shower transition curves.
Basic agreement in the PID parameter (L90) distribution
Checking systematics for SPS calibration data (50-200GeV for electrons, 150, 350 GeV for protons)
20mm cal.
MC (QGSJET2)
Data
hadron-like
g-like
Oscar Adriani Torino, 17/05/10

20. Preliminary spectra from 900GeV runs in 2009
Normalized by gamma-like entry
MC(QGSJET2)
Data
Hadron response
under study
Sys.+Sta.
Reasonable agreement with MC
Conservative systematic error for energy scale +10% -4% assigned
Checking detector response for hadron showers by SPS 350,150GeV p data
Adding May 900GeV runs, 100K showers now (Dec09 x15) !
Oscar Adriani Torino, 17/05/10

21. Oscar Adriani Torino, 17/05/10
Plan for coming months
Nominal data taking at 7TeV
Vertically shift Arm1&Arm2
Few runs for checking systematics with a few different configuration (HV, trig threshold, etc..)
High statistic with 1 or 2 settings (for h meson, etc. )
Possible beam crossing angle run (140mrad) at 7 TeV
Enhance rapidity coverage; h >8.7 g h>8.4
Important to check flux center moving downward w.r.t. crossing angle
Finally, LHCf de-installation
When luminosity becomes too high ( >1031cm-2s-1, or 2pb-1)
Typical unit 10K p0 w/ ~1nb-1
Oscar Adriani Torino, 17/05/10

22. Study of h in a high statistics sample
QGSJET2 h
Next milestone: h meson
h/p0 ratio or h production spectra vary a lot among different interaction models. A good handle to probe the models, though irrelevant to air shower development.
Another calibration point for more robust energy scale
Typical h/p0 =10-3~10-4 at 7TeV. Good to collect ~1M p0 (~100nb-1)
Strangeness production (K0, L) is under study
Oscar Adriani Torino, 17/05/10

23. Crossing angle for LHCf 7 TeV run
Shown in 99th LHCC, Sep2009
a=140mrad
Distance from neutral center
Aperture of
Beam pipe
TeV
All g from IP
2cm
No crossing
With 140mrad crossing angle,
neutral flux center is lowered by 2cm.
Rapidity coverage: >8.7 g >8.4.
w/o crossing : = 0.22
w mrad : = 0.22
If possible, it is nice to have a crossing angle during LHCf run.
LHCf can measure crossing angle by fitting shower center
(DY~ 1mm for to be distributed by DIP.
Oscar Adriani Torino, 17/05/10

24. Oscar Adriani Torino, 17/05/10

25. LHCf removal and toward the phase-2
When luminosity become too high (>1031 cm-2s-1, 2 pb-1), LHCf will go out from the TAN (Radiation damage at plastc scinitillator for 20% degradation)
De-installation work should be quickly done during monthly Technical Stop.
Not earlier than the next Technical Stop in June. We’d like to revisit the scheduling issue when LHC luminosity profile gets clearer in June.
After removal, beam calibration again by a SPS test beam.
Revisit LHC at the next energy upgrade. R&D and fabrication of rad-hard GSO scinitillator are on-going for the “phase-2” LHCf detector.
1mm thick
20mm
A new GSO scintillator layer
20mm
Oscar Adriani Torino, 17/05/10

26. Oscar Adriani Torino, 17/05/10
Summary
LHCf has started physics program very successfully.
100K showers at 900GeV
60M showers and 200K p0 at 7TeV
Detectors work beautifully without any serious trouble.
Very clean! Negligible beam-gas background
The p0 peak demonstrates good performance as expected.
As luminosity is growing up, high stat run and other optional runs are under discussion
High stat run for h mesons
Crossing angle commission f important step to “phase-2”
Rapid progress in analysis. Almost ready to publish physics !
900GeV results (2009&2010) and 7TeV results
Finalizing SPS test beam data to confirm energy scale, PID and hadron shower response at a few 100 GeV.
Oscar Adriani Torino, 17/05/10

27. Oscar Adriani Torino, 17/05/10
Backup slides
Oscar Adriani Torino, 17/05/10

28. Oscar Adriani Torino, 17/05/10

29. Both detectors working without any biases
Comparison between tower calorimeter towers of Arm2
Comparison of spectra
Gamma-ray like
Hadron like
Flat spectra in h>8.7
at 900GeV
Comparison between two Arms
Both detectors working without any biases
Oscar Adriani Torino, 17/05/10

30. Oscar Adriani Torino, 17/05/10
-Front Counter-
Thin scintillators with 8x8cm2 acceptance, which have been installed in front of each main detector.
Schematic view of
Front counter
We have a sub-detector with thin scintillator layers, we call Front Counter.
Front Counter has much larger acceptance than calorimeters.
It’s useful to monitor collisions and for background rejection of beam and residual gas collisions by coincidence analysis of both size.
To monitor beam condition.
For background rejection of beam-residual gas collisions by coincidence analysis
Oscar Adriani Torino, 17/05/10

31. Summary of Expected number of events
QGSJET2
SIBYLL
DPMJET3
Pythia h p0
h/ p0
Arm1
(Normal)
0.08
46.9
0.002
0.01
46.7
0.0002
75.5
0.0001
(-20mm)
7.35
238.4
0.031
0.21
191.9
0.0011
1.05
310.7
0.0034
Arm2
1.6
123.7
0.012
0.10
110.8
0.0009
0.24
177.5
0.0014
0.15
150
0.0010
(-10mm)
3.36
191.3
0.018
165.1
0.0013
0.47
268.5
0.0016
0.1
169
Oscar Adriani Torino, 17/05/10

32. LHCf can measure
Energy spectra and Transverse momentum distribution of
Gamma-rays (E>100GeV,dE/E<5%)
Neutral Hadrons (E>a few 100 GeV, dE/E~30%)
Neutral Pions (E>700GeV, dE/E<3%)
at psudo-rapidity range >8.4
The Aim is to calibrate hadron interaction models
for ultra high energy cosmic ray physics.
Next, I present what we can measure.
We can measure energy spectra and transverse momentum distribution of gamma-ray with more than 100GeV
and neutral hadrons it’s mainly neutrons with more than a few hundreds GeV, and neutral pions with more than 700GeV
at rapidity range from 8.4 to infinity.
because we don’t have own central detectors and LHCf trigger is completely independent on ATLAS trigger,
so LHCf can measure only inclusive spectra . However we are recording ATLAS event ID number event by event,
so it is possible to identify coincidence events with ATLAS event and to analyze with ATALS in future.
Energy
High energy flux !!
Low multiplicity !!
Oscar Adriani Torino, 17/05/10
simulated by DPMJET3

33. 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 Torino, 17/05/10

34. Comparing fill# 1031with ATLAS
ATLAS lumi
×1026
L*FC
1.7E+27
1.3E+27
L*FC is smaller than by 24%
Difference may come from interaction model
detector MC tuning
Oscar Adriani Torino, 17/05/10

35. Oscar Adriani Torino, 17/05/10