NKS Vertical Tracking( and etc)written at 2007/08/15

Tohoku Univ.

Kyo Tsukada

Method

• More than three hits of four stereo wires are required.

• Two z candidates, z1 and z2, are found by the horizontal trajectory.

• The relation, z=a+bx, is assumed in local coordinate.

• From the least 2 method, most probably track is selected in 2^(numofstereohits) tracks.

Analyzer (1)

• DCAnalysis::TrackSearch()– Horizontal tracking– SDC1,2,3, CDC4,5,8,9,12,13 are used.

• DCAnalysis::VerticalTrackSearch()– Vertical tracking– CDC6,7,10,11 are used.– Z information of vertical wires are calculated from vertical track

ing.

• PTrack::calcObservables()– Calculating the Time of flight, flight length, , mass, and so on.– The vertical angle of the track is estimated. The priority is as fo

llows,1. Result of PTrack::calcVerticalTrack().2. Z-information of OH as outer-side and the origin as other side.

Analyzer (2)

• PTrack::calcVerticalTrack()– Vertical tracking

– CDC6,7,10,11, IH and OH are used.

– z1 and z2 are already found in DCTrack::VerticalTrackSearch().

– dz of IH and OHH ~ zlen/sqrt(12), OHV ~ 2cm

– Z information of vertical wires are estimated from vertical tracking.

• ParticleAnalysis::SetTimeZeroCorrection(…)– Correcting the Time of DC by

• Time of IH associated a track

• Time difference between slow particle and electron.

• Tracking and vertical tracking again.

• PVertex3D::ConstructVertex()– Constructing a vertex from 3D tracjectories.

Search Nearest Hit

• For the killed layer method, DCTrack::SearchNearestHit is important.

• Now, it can work even for stereo layers.• We can also get the drift length calculated from trajectory

position.

We can derive the X-T curve of stereo layers.

X-T curves (before adjusting)

Stereo Layers

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X-T curves (after adjusting)

Stereo Layers

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Resolutions of January data

• 915.param : run915

• 908-925.param : run917

• 929-952.param : run940

• 956-968.param : run960

• 972-991.param : run981

• 992-1017.param : run 1006

• 1022-147.param : run1036

• 1051-1071.param : run1065

• 1075-1097.param : run1085

• 1101-1122.param : run1112

• Right figures show the mean and sigma of gaussian fits for the run used to adjust parameters.

Resolutions of all run

• Bottom figures show the mean and sigma of gaussian fits for all run.

• The time dependence of sigmas are reasonable because of the lack of the chamber gas at the beginning of the experiment.

• The mean of the residual is good only for the run used to adjust parameters.

• At least, the offset parameters should be corrected run by run.

Plane efficiencies of January data

• Bottom figures show the efficiencies for the run used to adjust parameters.

• The efficiencies are estimated in the range, 20degree<| angle |.

• Right bottom figures are the efficiencies with the distance cut, distance < 1.5*cellsize.

Vertical angular resolution (1)

z@OHVL2 from OHz@OHVL2 from OH w/EV

z@OHVL6 from OHz@OHVL6 from OH w/EV

z@OHVL2 from DCz@OHVL2 from DC w/EV

z@OHVL6 from DCz@OHVL6 from DC w/EV

z@OHVL2 from OHz@OHVL2 from OH w/EV

z@OHVL6 from OHz@OHVL6 from OH w/EV

z@OHVL2 from DCz@OHVL2 from DC w/EV

z@OHVL6 from DCz@OHVL6 from DC w/EV

-0.9 < cosOA < 0.8

The bump due to EV is clearly seen.

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Vertical angular resolution (2)

-0.9 < cosOA < 0.8Run1128-1157

Vertical angular resolution (3)

• Vertical distribution for each OH w/ EV.• For OHVL4 and OHVR4, the correspondence between OH and EV

are wrong.

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Vertical angular resolution (4)

• By taking the difference of adjacent bins, the resolutions are estimated.

• The shadow of EV and the edges of OH are used.

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Vertical angular resolution (5)

• The positions of the edges of EV and the vertex resolutions are estimated.

• The width of EV is 5 cm.• From tracking, the widths seems to be little narrow (?).• The sigma is less than 1 cm.

Left Right

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Vertical angular resolution (6)

• The positions of the edges of OH and the vertex resolutions are estimated.

• The height of OHV is 74.8 cm.• From tracking, the heights seems to be little small (?).• The sigma is about 1 cm.

Left Right

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Vertical angular resolution (7)

• The positions of the edges of OH and the vertex resolutions are estimated.

• Because the distribution is not flat, the fittings are done for one side of each OH.

• From tracking, the heights seems to be little low (?).

• The sigma is about 1-2 cm.

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Vertex resolutions in 3D

• Vertex resolution– The dx is estimated by the difference of the distribution.

– I could not find how to estimate the dy and dz.

– Right figures show the vertex distributions in target.

– If the beam size is negligible, this distributions give dy and dz.

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Resolution of Vertical angle

1. The vertical resolution at target is about 2 mm.

2. The vertical resolution at OH is about 10 mm.

3. The radius of OH from origin is typically 120 cm.

The angular resolution (d) is about 8.5 mrad.

Summary

• The vertical tracking works well.• For DC tracking, the time information of IH and OH are used.

• The plane resolutions are about 500 um for CDC and 300 um for SDC. These values include the tracking resolution.

• We should adjust the drift parameters run by run.• The plane efficiency are more than 98% in stable runs. But, in this st

udy, the efficiencies in the forward region are not estimated.

• The vertical position resolutions are about 10mm@OH and 2mm@target.

• The vertical angular resolution is about 8.5 mrad.• The z-position of the vertex point can be calculated.