SVT Track-Based Alignment - “The Good”

Early results with sim-ulated, type-1, cosmicevents (see below) withideal geometry in sim-ulation show residualsclose to zero and widthsnear specifications.

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 1 / 9

SVT Track-Based Alignment - “The Not-So Good”

Simulated, Type-2,cosmic events (seebelow) with idealgeometry in simulationshow large residualswith large widths.

L1S1

L1S5

L1S9

L1S2

L1S6

L1S10

L1S7

L1S3 L1S4

L1S8

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 2 / 9

SVT Track-Based Alignment - “More Not-So Good”

Simulated, Type-3,events originating fromthe target (see below)with ideal geometry insimulation show largeresiduals and widths.

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 3 / 9

SVT Diagnostics: Shooting at Strips

Test consistency of gemc and the SVTreconstruction geometry.

1 Calculate θ and φ for stripmid-points and endpoints usingthe reconstruction code.

2 Run gemc with those values of θand φ.

3 Is the hit in the right place?

Layer=1, sector=1, strip=1upstream end

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 4 / 9

SVT Diagnostics: Shooting at Strips

Test consistency of gemc and the SVTreconstruction geometry.

1 Calculate θ and φ for stripmid-points and endpoints usingthe reconstruction code.

2 Run gemc with those values of θand φ.

3 Is the hit in the right place?

Layer=1, sector=1, strip=1upstream end

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 4 / 9

SVT Diagnostics: More Shooting at Strips

Layer=1, sector=2, strip=1midpoint

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 5 / 9

SVT Diagnostics: More Shooting at Strips

Layer=1, sector=2, strip=1midpoint

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 5 / 9

SVT Diagnostics: Single θ − φ Events

Use the gemc particle gun to repeatedly fire protons at the midpoint of aparticular strip (center of layer 5, sector 14, strip 128) and histogram thereconstruction results. The peaks are very narrow, but far from zero.

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 6 / 9

SVT Diagnostics: Test the fitting of cosmic-ray tracks

Compare the reconstruction results (three crosses in the SVT) for protons on theprevious slide (center of layer 5, sector 14, strip 128) with other fitting methods.

recon SVD root

myx 7.327 7.15063 7.093 ± 13.187byx -0.352 0.00749 0.083 ± 17.825

myz 1.269 1.50052 1.220 ± 2.9241byz 0.294 0.03846 0.407 ± 3.9526

Red - SVDGreen - ReconstructionBlue - Root

L1S08 L2S08 L2S08 L3S11 L3S11 L4S11 L5S14 L6S14 L6S140.0

0.1

0.2

0.3

0.4

Sensor

Resid

ual(m

m)

Compare CVTRecon, SVD, and Root Fit Residuals

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 7 / 9

SVT Diagnostics: Single Topology Events

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 8 / 9

SVT Track-Based Alignment - “First Data”

Type-3 events from thealignment run (2467) andrestricted to the horizon-tal sections (see below)with ideal+survey geom-etry show large widthsmostly centered on zero.

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 9 / 9

SVT Track-Based Alignment - “First Data”

Type-3 events from thealignment run (2467) andrestricted to the horizon-tal sections (see below)with ideal+survey geom-etry show large widthsmostly centered on zero.

Jerry Gilfoyle CLAS12 SVT Track-Based Alignment 9 / 9