Track impact parameter resolution in the 2017 dataset with the CMS Phase-1 Pixel detector

Abstract

This note summarizes preliminary results on the measurement of the transverse impact parameter resolution of tracks using legacy data collected in proton-proton collisions in 2017 with the Phase-1 Pixel detector. The measurement is performed in unbiased collision events with respect to the beam-spot position. The resultant track impact parameter resolution is parameterized as a function of track transverse momentum and pseudorapidity.

Primary vertex position

Plots	Description
	Figure 1. Reconstructed position of primary vertices in the x-y projection as measured in unbiased collision data events. The measured beam width along the x and y coordinates is within [10, 16] μm.
	Figure 2. Reconstructed position of primary vertices in the x-z projection as measured in unbiased collision data events. The measured beam width and beam length are within [10, 16] μm and [30, 45] mm, respectively.
	Figure 3. Reconstructed position of primary vertices in the y-z projection as measured in unbiased collision data events. The measured beam width and beam length are within [10, 16] μm and [30, 45] mm, respectively.

Transverse impact parameter resolution

	Figure 4. The transverse impact parameter (IP) resolution measured as a function of track pT in unbiased collision events in data. The region of abs(η) < 1.4 corresponds to the coverage of the Phase-0 barrel Pixel detector [1, 2]. The measurement of the track impact parameter is performed with respect to the beam-spot position. The error bars on the measured points take into account the limited number of analyzed events and include the systematic uncertainty due to the finite bin width in the fitted distributions.
	Figure 5. Same as Fig. 4, but in log scale on y axis.
	Figure 6. The transverse impact parameter (IP) resolution measured as a function of track η in unbiased collision events in data. The indicated region of abs(η) < 1.4 corresponds to the coverage of the Phase-0 barrel Pixel detector [1, 2]. The measurement of the track impact parameter is performed with respect to the beam-spot position. The error bars on the measured points take into account the limited number of analyzed events and include the systematic uncertainty due to the finite bin width in the fitted resolution distributions.

References

[1] The CMS Collaboration, Tracking and primary vertex results in first 7 CMS.TeV collisions, CMS PAS TRK-10-005.

[2] The CMS Collaboration, Description and performance of track and primary-vertex reconstruction with the CMS tracker, JINST 9 (2014) P10009.

-- KirillSkovpen - 2020-06-28