G. Sirri – INFN BO 1Bern 13 Feb 2006

Scan back with dry objectiveG. Sirri for Bologna group

Dry objective with correction collar: ZEISS LD Achroplan (code 440864)

magnification: 40x (nominal)numerical aperture: 0.60working distance: 1.8 mmcorrection 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

G. Sirri – INFN BO 2Bern 13 Feb 2006

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 anintermediate correction (c.c. 0.15)

different magnification Top/Bottom0.310 µm/pixel (c.c. 0, top)0.305 µm/pixel (c.c. 0.3, bottom)

Focal plane shifts due to the correction (~ 10 µm)

G. Sirri – INFN BO 3Bern 13 Feb 2006

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

G. Sirri – INFN BO 4Bern 13 Feb 2006

Angular residuals (pred – found)

Black = dryRed = oil

G. Sirri – INFN BO 5Bern 13 Feb 2006

Position residuals (pred – found)

Black = dryRed = oil

G. Sirri – INFN BO 6Bern 13 Feb 2006

Out of 325 predictions:

248 passing through (last found plate >53)

77 stopping points

entr

ies

Scanning efficiency (on passing tracks)

Stop plate

G. Sirri – INFN BO 7Bern 13 Feb 2006

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) MIC2 MIC3

P P P 223

P P X 11

P X P 12

X P P 14

P X X 2

X P X 6

X X P 2

X X X 55

35 identified by all microscopes

G. Sirri – INFN BO 8Bern 13 Feb 2006

Efficiency (passing tracks)

Green = DRYBlue = OIL (mic3)

G. Sirri – INFN BO 9Bern 13 Feb 2006

Segments of stopping tracks

Green

G. Sirri – INFN BO 10Bern 13 Feb 2006

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.