1. Experimental Method: 2 independent detectors on both sides of IP
The direct measurement of the p production cross section as function of pT is essential to correctly estimate the energy of the primary cosmic rays
(LHC: 1017 eV)
Simulation of an atmospheric shower due to a 1019 eV proton.
Experimental Method: 2 independent detectors on both sides of IP
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
140 m
140 m
Beam line

2. ARM #1 detector scintillating fibers tungsten layers
2 towers (2.02.0cm2 and 4.04.0 cm2)
~47 r.l. (22  2.1 r.l. tungsten layers)
16 scintillator layers (3 mm thick)
4 pairs of scintillating fiber layers for tracking purpose (two orthogonal directions)
scintillators
Energy
Impact point (h)

3. ARM #2 detector See TDR for details…
We used LHC style
electronics and readout
2 towers (2.52.5cm2 and 3.53.5 cm2)
44 r.l. (22  2 r.l. tungsten layers)
16 scintillator layers (3 mm thick)
4 pairs of silicon microstrip layers for tracking purpose (X and Y directions)
Energy
silicon layers
Impact point (h)
See TDR for details…
scintillators
tungsten layers

4. Monte Carlo g ray energy spectrum
(5% Energy resolution is taken into account)
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
(see TDR for details)

5. Where we are with Arm1?
Arm1 was fully assembled in Japan in July 2006 (scintillators + fibers + Tungsten) and brought to CERN for the Beam Test
Arm1 was pre-installed in the real TAN last week!!!

6. Where we are with Arm2?
Plastic scintillators + Light guides + Tungsten:
Production in Japan finished in July 2006
They were brought in Florence end of July
First Silicon module (Milestone INFN):
Production in Florence finished in July 2006
Assembly of Arm2:
It was done in Florence in August 1-15
Arm1 was brought at CERN for the beam test on August 16, 2006
To complete Arm2 3 more silicon moudules are needed
They are now in production
Arm2 will be pre-installed in the TAN end of April

7. Plastic scintillators + Light guides + Tungsten
Florence clean room (thanks to CMS!!!!!)

8. The mechanics of the module
25 mm
Light Guides +
Scintillators
Hybrid circuit
Pace Chips
Silicon sensor
Kapton fanout
Tungsten
SiliconX SiliconY

11. The hybrid and the cables
PACE3

12. The readout and ADC boards
CCUM
QPLL
PLL

13. Beam test @ SPS Arm1 & Arm2 were delivered to Cern on August 16, 2006
They were set up for the beam test
Beam period: August 28, September 4
H4 Test Area
Electrons up to 200 GeV
Protons up to 350 GeV
Muons
Goal of the test beam:
Energy calibration of the calorimeter
Measurement of the spatial resolution of silicon system
Florence telescope (ADAMO) is used to precisely reconstruct tracks

15. Few plots of the beam test results…
A high energy electron shower seen on x and y silicon X Y
<Noise> ~ 5 ADC counts

16. Y
Beam profile
200 GeV electrons X

17. Y
Energy measured
200 GeV electrons
Low Gain X

18. Y
Energy measured
100 GeV electrons
High Gain X

19. Y
Energy measured
350 GeV protons
High Gain X

20. SPARES

21. Transverse projection of detector #2 in the TAN slot
Maximization of the acceptance in R (distance from beam center)

22. Position resolution of Arm #2 calorimeter
7 mm for 1.8 TeV photons

23. p0 geometrical acceptance
Arm #2
Arm #1

24. p0 mass resolution
Arm #1
DE/E=5%
200 mm spatial resolution
Dm/m = 5%