1. The HADES RPC Cosmic Ray Telescope:
Preliminary Analysis
Pablo Cabanelas
Laboratorio Carmen Fernández, USC
Proyecto
2nd Workshop, Compostela, February 2010

2. OUTLINE:
● Overview of the HADES RPC ToF Wall
● The Cosmic Ray Commissioning
● Close to the first TRASGO
● Preliminary Analysis Results

3. RPC

4. The HADES RPC ToF Wall
Consist on 1122 shielded 4-gap timing RPC cells
(0.280mm/gap), covering about 8m2, distributed like this:
● 6 almost-identical sectors
● 2 RPC layers per sector
● 3 columns of RPC cells per layer
● 31 RPC cells per column

5. The RPC Commissioning
From April 2009 to nowadays
1. The 6 sectors were instrumented by pairs at the
GSI and placed at horizontal position.
2. Cosmic Ray test was performed with such a
setup.
3. At the end, they were mounted on their nominal
position in HADES.
4. Currently, they are just there, a bit bored,
waiting for a beam to take data.

13. Hit distribution of cosmic rays over the 6 RPC sectors

14. Cosmic ray commissioning summary:
● 6 RPC sectors fully instrumented, tested,
validated and mounted in HADES
● About 50 days of data taken at a rate of 200
Hz over a pair of sectors
● 895 Gb of data stored
● 1122 RPC cells operative as well as 2243
channels (all but one!)

15. Preliminary Cosmic Ray Analysis with TimTrack
Proyecto
timtrack
timtrack
timtrack timtrack
timtrack A Tracking Algorithm for
timtrack TRASGOS
timtrack Already introduced
timtrack
timtrack To be presented by
timtrack J.Garzón
ttrack
tim
imtrack

16. TimTrack: L
x
z
X’ V
X0 T0
Vz
z=0 Y’
Y0 y

17. Preliminary Cosmic Ray Analysis with TimTrack
Analyzed events crossing
one set of four RPC cells
~42cm
~5cm
33cm
Ref Plane
Z
X

18. Preliminary Cosmic Ray Analysis with TimTrack
Some Ultra-Preliminary Results!!!
Reconstructed X at the
reference plane
Reconstructed X vs X' (slope):
acceptance

19. Preliminary Cosmic Ray Analysis with TimTrack
Some Ultra-Preliminary Results!!!
~6-8 ns
Two-Peak
structure
Reconstructed T0 (Time at the reference
plane) in ps [Not calibrated]

20. Close to the first TRASGO ??
2 HADES RPC sectors:
TRASGO:
Four planes of shielded 4-
Several planes (4 at least)
gap RPCs
of ?-gap RPC strips
Different Geometry -- Same FEE, DAQ and Analysis