Misalignment studiesMisalignment studiesMS z misalignments MS z misalignments Barrel and EndcapBarrel and Endcap

Peter Kluit,

Muon week meeting 15 NovemberSummary of results 5/15 october

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Based on the v35 processing of the Z skimmed data

Focussing on MS misalignmentsFocussing on MS misalignments

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Study was initiated by so-called Afb effect- CB momentum suffered from systematic eta dependent effects- Traced down to misalignment in z of MS and ID- Here below it is pinned down to misalignments in the Muon system

Using muons from Z events in ZMUMU v35 (release 17) processing.

Will be done in three ways:A)Comparison of MS-MS parameters: z0-z0B) Comparison of MS-ID z0 parameter

- Z0 of ID is consistent and precise to better than 0.1 mm apart from ONE global z shift

C) comparing theta ID and SA

Try to understand and model the Endcap structure: Barrel is more simple.

Looking at z0 SA – z0 SALooking at z0 SA – z0 SAfor MS Barrel-Barrel eventsfor MS Barrel-Barrel events

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Select eta1<0 and eta2 >0 events and plot plot dz = z(eta>0) – z(eta<0)

So Barrel A and C are not consistent at 2 mm level

z0 SA – z0 SAz0 SA – z0 SAfor MS Barrel-Endcap eventsfor MS Barrel-Endcap events

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plot dz = z(EC) – z(Barrel) both in eta >0 or both in <0

So Barrel and Endcap are not consistent at a few mm level- It is known that B-E overlap are not consistent- See also slide 9 that demonstrate this wrt z0 of ID

Looking at z0 SA – z0 SALooking at z0 SA – z0 SAA simplified model for the A simplified model for the

EndcapEndcap

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A possible deformation would look like this- Keeps the z distance between A-C approx. constant- not only a z shift of endcap A or C: can be added- has feature that dz vs eta is linear for Endcap AA or CC eventsCan be tested and refined selecting Endcap-Endcap events:- Events A-C (z distance between AC) and AA or CC events

z

R (sign)

Inspired by the linear trend in slide 4

CSC region might be more complicated

Looking at z0 SA – z0 SALooking at z0 SA – z0 SAMS Endcap A-CMS Endcap A-C

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Plotted eta in EC A

Means that EC distance is correct at ~2 mm level

Recall slide MCP

z0 SA – z0 SAz0 SA – z0 SAMS Endcap AAMS Endcap AA

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Plotted delta eta of the two muons in EC A

So: dz/deta = -6 mm/ unit rapidityBy ‘definition’ through 0

Or 9 mm/1.5 rap Quite unexpected…

z0 SA – z0 SAz0 SA – z0 SAMS Endcap CCMS Endcap CC

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Plotted delta eta of the two muons in EC A

So: dz/deta = -4.4 mm/ unit rapidityBy ‘definition’ through 0

Or 6.6 mm/1.5 rap Quite unexpected…

A and C seem to behave similarly

A telescope model for the A telescope model for the EndcapEndcapBasically the same as the one on slide 5There are however NO z(R) shiftsThere are rotations + small shifts (~1 mm). theta’ = theta + dthetaThis generates a z0’: z0’ = z0 +/- 7000*dtheta/sin2(theta)Value of dtheta = 30 μrad (A side) and 50 μrad (C) This value is compatible with Survey and alignment

constraints

Interpretation: telescope effect in Endcap i.e. small rotations (dR/dz) that are phi sector dependent

This is consistent with the observed sector dependence

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z0 ID – z0 SA at primary vertex z0 ID – z0 SA at primary vertex

before/after correction for before/after correction for dthetadtheta

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Tighted MS track selection to three station tracks with NO EE chambers and NO Barrel-Endcap

Before After

Flattened:

z0 SA – z0 SA correctedz0 SA – z0 SA correctedMS Endcap AAMS Endcap AA

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Plotted delta eta of the two muons in EC A

Now flat!

z0 SA – z0 SA correctedz0 SA – z0 SA correctedMS Endcap CCMS Endcap CC

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Plotted delta eta of the two muons in EC C

Now flat!

z0 SA – z0 SA correctedz0 SA – z0 SA correctedMS Endcap A-CMS Endcap A-C

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Plotted eta in EC A

Means that EC distance is correct at ~2 mm level

After correction results more compatible with 0

Conclusion: Model in slide 9 seems to do the job

z0 ID –z0 SA correctedz0 ID –z0 SA correctedEndcap: Endcap: eta Sector projectionseta Sector projections

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Interpretation: dtheta is sector dependent and small misalignments cause q splitting

z0 ID –z0 SA correctedz0 ID –z0 SA correctedEndcap: Endcap: eta Sector projectionseta Sector projections

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z0 ID –z0 SAz0 ID –z0 SABarrel: Barrel: eta Sector projectionseta Sector projections

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Different interpretation for the Barrel: Here we have z shifts that are sector dependentThe charge splitting could be due to misalignment in position and/or angle

z0 ID –z0 SAz0 ID –z0 SABarrel: Barrel: eta Sector projectionseta Sector projections

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Endcap: q* (z0 ID –z0 SA) and Endcap: q* (z0 ID –z0 SA) and q*(theta ID- theta SA) correctedq*(theta ID- theta SA) corrected

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Very similar shapes in dz and dtheta plots: implies that structure comes from dtheta MS endcap misalignments: in agreement with the model

Endcap: q* (z0 ID –z0 SA) and Endcap: q* (z0 ID –z0 SA) and q*(theta ID- theta SA) correctedq*(theta ID- theta SA) corrected

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Very similar shapes in dz and dtheta plots: implies that structure comes from dtheta MS endcap misalignments: in agreement with the model

Barrel: q* (z0 ID –z0 SA) and Barrel: q* (z0 ID –z0 SA) and q*(theta ID- theta SA) correctedq*(theta ID- theta SA) corrected

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Very similar shapes in dz and dtheta plots: implies that structure comes from MS Barrel z/theta misalignments.

Barrel: q* (z0 ID –z0 SA) and Barrel: q* (z0 ID –z0 SA) and q*(theta ID- theta SA) correctedq*(theta ID- theta SA) corrected

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Very similar shapes in dz and dtheta plots: implies that structure comes from MS Barrel z/theta misalignments.

ConclusionsConclusions

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- An Interpretation for the Endcap is proposed: telescope effect in Endcap i.e. small rotations (dR/dz) that are phi sector dependent. Plus small shifts of the Endcap (~1 mm).- Correcting for the Endcap Model gives dtheta values of 30 and 50 microrad- These values are in agreement with constraints from Survey and the optical alignment.- The distributions in Endcap A and C are after correction flat- Detailed study of the sector dependent effects show that:

- Endcap dtheta correction is sector dependent - Endcap q*misalignments in MS are observed in z0 and theta (wrt ID) -> misalignment within one sector- Everything compatible with dtheta << 50 microrad

ConclusionsConclusions

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- The results in the Barrel can be interpreted as a set of sector dependent z shifts- This is in agreement with constraints from Survey and the optical alignment.

- Looking into more detail at q*dz and q*dtheta (appended) plots structures are observed indicating misalignments in z/theta inside a sector. - Note that also clear MS effects within one sector are observed.- This is further confirmed by very high statistics studies performed by Phillipp Fleischmann.

- What we learned from this:- can improve the alignment- using a z0 constraint might help a lot- Pierre-Francois Giraud is implementing this for the Barrel- For the Endcap Christoph and Ben and I look into this

theta ID –theta SA correctedtheta ID –theta SA correctedEndcap: Endcap: eta Sector projectionseta Sector projections

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Interpretation: the observed structures are probably too big to come from the MS

theta ID –theta SA correctedtheta ID –theta SA correctedEndcap: Endcap: eta Sector projectionseta Sector projections

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Interpretation: the observed structures are too big to come from the MS

theta ID – theta SAtheta ID – theta SABarrel: Barrel: eta Sector projectionseta Sector projections

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Interpretation for the Barrel?Looks like a global dtheta vs phi structure

theta ID – theta SAtheta ID – theta SABarrel: Barrel: eta Sector projectionseta Sector projections

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Interpretation for the Barrel?Statistics?