1. Status report of the LHCf experiment: preparation for data taking
Commissione Nazionale Scientifica I
Pisa, Settembre 2008
Status report of the LHCf experiment: preparation for data taking
Oscar Adriani
INFN Sezione di Firenze - Dipartimento di Fisica dell’Università degli Studi di Firenze

2. LHCf: location and detector layout
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
IP1 (ATLAS)
140 m
140 m
Beam line
Detectors should measure energy and position of g
from p0 decays e.m. calorimeters with
position sensitive layers
Two independent detectors on both side of IP1
Redundancy
Background rejection (especially beam-gas)
18 Settembre 2008
CSN1 – Pisa O. Adriani

3. LHCf location
Detectors installed in the TAN region, 140 m away from the Interaction Point, in front of luminosity monitors
Here the beam pipe splits in 2 separate tubes.
Charged particle are swept away by magnets!!!
We will cover up to y
18 Settembre 2008
CSN1 – Pisa O. Adriani

4. Detector #1 Impact point (h) Energy
2 towers 24 cm long stacked vertically with 5 mm gap
Lower: 2 cm x 2 cm area
Upper: 4 cm x 4 cm area
4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 r.l.)
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
Energy
18 Settembre 2008
CSN1 – Pisa O. Adriani

5. Detector # 2 Impact point (h) Energy
We used LHC style
electronics and readout
Impact point (h)
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
4 pairs of silicon microstrip layers
(6, 12, 30, 42 r.l.) for tracking purpose (X and Y directions)
16 scintillator layers (3 mm thick)
Trigger and energy profile measurements
Absorber
22 tungsten layers mm – 14 mm thick (2-4 r.l.)
(W: X0 = 3.5mm, RM = 9mm)
Energy
18 Settembre 2008
CSN1 – Pisa O. Adriani

6. Double ARM Detectors 290mm 90mm Arm#2 Detector Arm#1 Detector
18 Settembre 2008
CSN1 – Pisa O. Adriani

7. Installation Final installation was completed in January 2008
No major problems have been found
Both Arm1 and Arm2 are working fine
No additional noise is found in the detectors, despite 200 m long power lines and signal cables (for the scintillators)
The only problem: quartz optical fiber for laser calibration (yet another fiber problem…..)
The quartz fiber for N2 laser calibration was broken last year during installation
The new fiber was installed in January … but….
Problems in the connectors installation…. After this…..
Unfortunately we discovered the fiber was the wrong one!!!!!!!!!!!!
New and final installation in the last week free for access (May)
Now is finally OK!
18 Settembre 2008
CSN1 – Pisa O. Adriani

8. Detectors in place Installation performed in two phases:
Pre-Installation (2007)
Baking out of the beam pipe (200 °C)
Final Installation (Jan 2008)
LHCf
Luminosity
Monitor (BRAN)
ATLAS ZDC
18 Settembre 2008
CSN1 – Pisa O. Adriani

9. Some problems of grounding have been solved….
18 Settembre 2008
CSN1 – Pisa O. Adriani

10. 18 Settembre 2008
CSN1 – Pisa O. Adriani

11. Counting room cables clean-up
18 Settembre 2008
CSN1 – Pisa O. Adriani

12. Front Counter
2 fixed Front Counters were installed in front of Arm1 and Arm2
They will not move with Arm1 and Arm2
They are segmented in 2 x and 2 y slices
Very useful to check the beam quality and hence decide to move Arm1 and Arm2 in the operating position from the ‘garage’ position
18 Settembre 2008
CSN1 – Pisa O. Adriani

13. After the installation….
After the installation was completed, a lot of work on:
DAQ
New VME board to increase DAQ rate up to > 1 KHz
Integration of all the subsystem (Using MIDAS frame)
Analyzer to check the data quality and online monitor
Slow control software to control and monitor:
Power supplies
Manipulator
Temperature monitor
LHC interface
New NIM style board (CIBU) to send ‘PERMIT’ to LHC (KILL the beam in case of high rate)
Handhshaking software signals (DIP standard) for Injection, Adjust and Beam Dump
LHCf Physics information (beam position, rate, background etc.)
18 Settembre 2008
CSN1 – Pisa O. Adriani

14. An Update on the 2007 SPS Beam Test
Test was very successful!!!!
Energy calibration of the calorimeters
Spatial resolution of the tracking systems
Results were partially published on JINST:
2008 JINST 3 S08006
CERN : SPS T2 H4
August/September 2007
Incident Particles
Proton　 150,350 GeV/c
Electron 50, 100, 150, 200 GeV/c
Muon GeV/c
Setup
LHCf
Detector
Silicon
Tracker
Moving Table
Trigger
Scintillator
18 Settembre 2008
CSN1 – Pisa O. Adriani

15. Energy Resolution Monte Carlo Test Beam
N Particles
Distance from Edge
Energy distribution is corrected for leakage
MC predicts that the
leakage is energy independent!
18 Settembre 2008
CSN1 – Pisa O. Adriani

16. Energy Resolution Energy resolution < 3% even
2 x 2 cm2 tower
2.5 x 2.5 cm2 tower
Energy resolution < 3% even
for the smallest tower!
18 Settembre 2008
CSN1 – Pisa O. Adriani

17. Simulation vs Data Simulation is very well understood!
150 GeV m
Energy released in the
4° scintillation layer
Simulation is very
well understood!
100 GeV e-
18 Settembre 2008
CSN1 – Pisa O. Adriani

18. in the slot used for beam monitor
p0 reconstruction g
350 GeV Proton beam
Not in scale! g
Carbon target (3 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 has been used
Egamma=18GeV
Shower First SciFi Layer
Calorimeters
20mm X
40mm Y
Egamma=46GeV
18 Settembre 2008
CSN1 – Pisa O. Adriani

19. p0 mass reconstruction Dm ~ 8 MeV Dm/m ~ 6% Preliminary!!!! (MeV)
 250 p0 events triggered (in a quite big background) and on disk
Preliminary!!!!
(MeV)
Main problems:
low photon energy (≥ 20 GeV)
Direct protons in the towers
Multi hits in the same tower
Dm ~ 8 MeV
Dm/m ~ 6%
18 Settembre 2008
CSN1 – Pisa O. Adriani

20. ARM1 Position resolution
200 GeV electrons
sx=172 mm
Number of event
σx[mm]
x-pos[mm]
E[GeV]
σy[mm]
sy=159 mm
Number of event
y-pos[mm]
E[GeV]
18 Settembre 2008
CSN1 – Pisa O. Adriani

21. ARM2 Position Resolution
200 GeV electrons
sx=40 mm
x-pos[mm]
sy=64 mm
y-pos[mm]
Alignment has been taken into account
18 Settembre 2008
CSN1 – Pisa O. Adriani

22. ARM2-Silicon Energy Resolution
200 GeV electrons
SPS beam test data
DE/E ~ 12%
Total energy measured in silicon (ADC)
By looking only at the silicon energy measured, we have an energy resolution ~ 10%!!!!!
We can use it as a check for the radiation damage of the scintillators
18 Settembre 2008
CSN1 – Pisa O. Adriani

23. Linearity in the Silicon Energy
Correction for energy
leakage is not applied
At least in the GeV energy range the
silicon energy measurement is linear
18 Settembre 2008
CSN1 – Pisa O. Adriani

24. Preparation for data taking
A ‘control room’ …. has been prepared since there was no space for us in the Atlas buildings ….
18 Settembre 2008
CSN1 – Pisa O. Adriani

25. But our Control Room is fully equipped!
Furnitures
Telephones
Air conditioner
Network
Computers
Printers ……
And also with Japanese students!!!!!
18 Settembre 2008
CSN1 – Pisa O. Adriani

26. Dummy event
18 Settembre 2008
CSN1 – Pisa O. Adriani

27. Communications with LHC
LHCf sends signals to LHC through the DIP system.
Link have been tested and it works fine!
Important for machine tuning!
We are in strict contact with them.
Experimental status (On/Off, Gain, etc.)
Detector position (Garage/Operating, position in mm, etc.)
Luminosity rate (Single and Double Arm)
Front Counter rate (single Arm, double Arm coincidence)
Small tower rate (single Arm)
Big tower rate (single Arm)
Double Arm coincidence rate (FC.AND.Towers in opposite sides)
Horizontal and Vertical position of the Beam (every events or in the whole RUN)
Injection Inhibit
Handshaking signals (Injection, Adjust, Beam Dump)
18 Settembre 2008
CSN1 – Pisa O. Adriani

28. We are ready for data taking
On September 10 we observed some signals on Front Counters, with Arm1 and Arm2 in garage position for safety reasons
That day the Atlas BPTX signal was still not available (no info on the real bunches in the Atlas zone)
On September 11 Atlas gave us the synchronized BPTX signals, and we could take Front Counter data by using this signal (still in garage position)
We are measuring Beam-Gas from the Beam2 on Arm1 side
18 Settembre 2008
CSN1 – Pisa O. Adriani

29. 18 Settembre 2008
CSN1 – Pisa O. Adriani

30. ‘Analysis’ of Beam Gas events
We got 116 FC triggers in BPTX: Nt=116
2.109 protons/bunch
Total # of protons: Np=1.7 x 1016
We try to estimate the gas density r from this rate:
Nt=Np* L * s * r
L=effective lenght ~ 100 m
s=Cross section ~ 80 mbarn = 80 x m2
We find: r = 8.5 x 1012 H/m3 = 4.2 x 1012 H2/m3
From the LHC Project Report #783: r = 1012 H2/m3
From the pressure measurement in April 2008: r ~ 1012 H2/m3
~ CONSISTENT!!!!!!!!!!!!!
18 Settembre 2008
CSN1 – Pisa O. Adriani

31. While waiting for collisions….
Proton
A short comment on new models: PICCO, EPOS Very big interest in LHCf data and in this physics field
Drescher, Physical Review D77,
(2008) p0
Neutron
18 Settembre 2008
CSN1 – Pisa O. Adriani

32. LHCf : Monte Carlo discrimination
106 generated LHC interactions 
1 Minute cm-2s-1 luminosity
Discrimination between various models
is feasible in a very short time
Quantitative discrimination with the help of a properly defined c2 discriminating variable based on the spectrum shape
(see TDR for details)
5% Energy resolution
18 Settembre 2008
CSN1 – Pisa O. Adriani

33. Conclusions A lot of work has been done in 2008 Installation completed
Preparation for running completed
First beam gas events acquired
Will we get collisions today???
We are ready to send our info to LHC for beam tuning
18 Settembre 2008
CSN1 – Pisa O. Adriani

34. Spare slides

35. Radiation Damage Studies
Scintillating fibers and scintillators
Expected dose: 100 Gy/day at 1030 cm-2s-1
Few 1030 cm-2s-1: 10 kGy
50% light output
Continous monitor and calibration with Laser system!!!
30 kGy
18 Settembre 2008
CSN1 – Pisa O. Adriani

36. Estimate of the background
beam-beam pipe
 E γ(signal) > 200 GeV, OK
background < 1%
beam-gas
 It depends on the beam condition
background < 1% (under Torr)
beam halo-beam pipe
 It has been newly estimated from the beam loss rate
Background < 10% (conservative value)
18 Settembre 2008
CSN1 – Pisa O. Adriani

37. Effect of LHCf on BRAN measurement
LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar)
IP1
Cu Bar / ZDC
LHCf
LHCf
Cu Bar / ZDC
Lumi
Lumi
The effect of LHCf on BRAN measurements has been studied in the last months by simulation
Reduction of shower particles at BRAN
Position dependence on beam displacement
(question from machine peoples: if we shift by 1 mm the real beam, does the center of the measured neutral energy shifts by 1 mm?)
18 Settembre 2008
CSN1 – Pisa O. Adriani

38. LHCf performances: p0 geometrical acceptance
Arm #1
Arm #2
18 Settembre 2008
CSN1 – Pisa O. Adriani

39. LHCf performances: energy spectrum of p0
Typical energy resolution of g is 3 % at 1 TeV
18 Settembre 2008
CSN1 – Pisa O. Adriani

40. 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)
18 Settembre 2008
CSN1 – Pisa O. Adriani

41. LHCf: model dependence of neutron energy distribution
Original n energy
30% energy resolution
18 Settembre 2008
CSN1 – Pisa O. Adriani