STAR/ALICE Group
SSD beamtest

Experimental Set-up for SSD beamtest (September 2003)

The first four prototype SSD modules corresponding to the final design were tested using a secondary 7 GeV/c pion beam produced at the CERN PS accelerator.

Schematic layout of the beam test set-up. The four modules under test were surrounded by the trigger scintillators A,B and C. On the right, view of the tested modules.

Noise and signal to noise ratio

Charge in clusters for one module. For the calibration, we assumed that the maximum of the distribution corresponds to a charge of 22000 electrons (charge deposited by a MIP particle in a 300µm Si layer).

Noise and signal to noise ratio for the modules.
Module Number	Median strip noise, electrons		S/N ratio
Module Number	P-side	N-side	P-side	N-side
1	435	1487	57	18
2	435	1415	56	18
3	354	559	70	45
4	331	575	75	43

The low S/N ratio for module 1 and 2 is due to higher noise on the N-side of these modules (the problem has been solved by the manufacturer).

Charge matching

Correlation between P-side and N-side cluster charge. The deviation from perfect matching is about 6% for module 3 and 4 and 8% for module 1 and 2.

Spatial resolution

After modules alignment, 3 modules are taken as reference and the dispersion of the track residuals on the fourth module gives the spatial resolution. As there is no additional reference detector, resolutions found are higher than the nominal ones (20um in rphi direction and 820um along z) and are worse for outer modules (1 and 4).

	resolution in rphi(µm)	resolution in z(µm)
Module 1	32.8±0.8	1471±8
Module 2	19.9±0.1	987±5
Module 3	20.5±0.1	975±6
Module 4	31.7±0.2	1478±9

Publications

For more details about these results see ALICE note ALICE-INT-2005-028 (Approved-Collab.) or contact Stephane Plumeri.
A more complete analysis will be available soon in a NIM paper.