Bern 13 Feb 2006 G. Sirri – INFN BO1 Scan back with dry objective G. Sirri for Bologna group Dry objective with correction collar: ZEISS LD Achroplan (code ) magnification: 40x (nominal) numerical aperture: 0.60 working distance: 1.8 mm correction range: 0-2 mm The collar has been motorized with a DC motor and a drive belt. The motor controller are connected through a serial line. Efficiency, angular residuals, position residuals, base-track density on the non-exposed plate were already shown (behavior similar to the oil). Working conditions: two collar position c.c. 0 for the TOP scanning c.c. 0.3 for the BOTTOM scanning Analysis of the reference brick: efficiency : >90% angular residuals: 1.0 mrad [at 0 mrad], 4.5 mrad [at 400 mrad] position residuals: 1 µm [at 0 mrad], 3 µm [at 400 mrad] base-track density on the non-exposed plate = 4.0 tr/mm2/||<0.4 rad

Bern 13 Feb 2006 G. Sirri – INFN BO2 Software implementation  The acq. software has been modified in order to move the collar during the ACQ and to minimize the time to switch from Top to Bottom positions. Main points:  Interface to the controller implemented inside VertigoScan.  Switch the collar position during focusing, scan and “single view” scan  Fiducial marks finding with an intermediate correction (c.c. 0.15)  different magnification Top/Bottom µm/pixel (c.c. 0, top) µm/pixel (c.c. 0.3, bottom)  Focal plane shifts due to the correction (~ 10 µm)

Bern 13 Feb 2006 G. Sirri – INFN BO3 DB scan back setup  Same brick and predictions of the oil scan back in order to compare the results. 325 predictions (coming from a general scan of the first 10 plates up to 0.4 rad,  see Michela talk) same DB intercalibration performed with oil  Minor changes in the acquisition parameters: cluster size >= 3 n° of grains per microtrack >= 6 CIMG2063.AVI

Bern 13 Feb 2006 G. Sirri – INFN BO4 Angular residuals (pred – found) Black = dry Red = oil

Bern 13 Feb 2006 G. Sirri – INFN BO5 Position residuals (pred – found) Black = dry Red = oil

Bern 13 Feb 2006 G. Sirri – INFN BO6 Out of 325 predictions: 248 passing through (last found plate >53) 77 stopping points entries Scanning efficiency (on passing tracks) Stop plate

Bern 13 Feb 2006 G. Sirri – INFN BO7 Comparison with two oil scan backs  Scan back preformed on 2 oil microscopes (MIC2, MIC3) and on the dry microscope (MIC1)  Out of 325 predictions … (P = passing through, X = stopping) MIC1 (dry)MIC2MIC3 PPP223 PPX11 PXP12 XPP14 PXX2 XPX6 XXP2 XXX55 35 identified by all microscopes

Bern 13 Feb 2006 G. Sirri – INFN BO8 Efficiency (passing tracks) Green = DRY Blue = OIL (mic3)

Bern 13 Feb 2006 G. Sirri – INFN BO9 Segments of stopping tracks Green

Bern 13 Feb 2006 G. Sirri – INFN BO10 Conclusions  Also in the scan back procedure, the dry objective with correction collar results are very similar to the oil case.  The total scan (with this objective) and the vertex confirmation are in progress.  A Nikon dry objective with correction collar is under test and will be motorized soon.