1 saw tooth and remedies - elena wildner saw tooth elenawildner and natalia emelianenko at/mas the...

1Saw Tooth and remedies - Elena Wildner

SAW TOOTH

ElenaWildner and Natalia Emelianenko AT/MAS

The saw tooth effect in the geometry measurements,possible remedies by data treatment


Outline

I. Description of problem

II. Reasons for the effect

III. Evaluation criteria

IV. Results of the evaluation

V. Conclusion


I. Description of the problem 1

Result from measurement after cold test.Questions: Why do the spools “move” by up to 0.5 mm from industry measurement to CERN measurement?Why are measurements varying up to 1 mm along the axis?

The two measurements from both sides of the magnet separated:

Red: connection side

Blue: lyra side

The analysis is made for the Dipole where the effect is significant

Magnet 2248



1 1 2 3 4ym

0.4

0.3

0.2

0.1

0.1

0.2

0.3

0.4

txt

Best fit of data taken from lyre side

Best fit of data taken from connection side

Reference line

Final result

The idea: Consider the point close to the Tracker more correct than points far from the Tracker.

By superposing the curves while keeping fix the points close to the tracker, we can reduce the saw tooth considerably and retrieve the shape

The questions: What do the effect(s) come from ?Where is the new GA ?Is the deviation linear ?Is the procedure applicable to different kinds of errors?Where exactly are the “fix points” ?What are the criteria for a good data treatment?What best fits to apply for the measurement curves to be rotated?Etc……



D.Missiaen, M, Dupont, P. Winkes: The Laser Tracker: a major tool for the metrology of the LHC, IWAA2004, CERN, Geneva, 4-7 October 2004



E. Ainardi, L.Bottura, and N.Smirnov, “Light beam deflection through a 10m long dipole model”, CERN LHC-MTA, Tech. Rep. May 1999.

N. Smirnov et al. “The methods of the LHC Magnets’ Magnetic Axis Location Measurement”. IWAA 1999.

P.Schnizer et al. “Experience from measuring the LHC Quadrupole axes”. IWAA 2004.Interesting reading! What we use for our presentation are the following facts from these articles:

1. We may have a longitudinal temperature difference along the magnet2. This may cause a convection cell at the ends of the magnet at ~ 0.2 m

from the cold bore ends 3. The convection cells deflect the light beam4. Act only in the vertical plane

0.2

error

tracker

lens



To sum up:

Bundle (best fit on network points of several measurements to have the measurements in the same reference system): 0.08 mm rms at any position (3 ~ 0.2 mm).

Calibration centring error: 0.07 mm. This is not visible in the vertical plane and considered = 0 for the treatment.

Leica errors with distance: 5 ppm (rms) which translates to 0.005*3 mm for close points and 0.075*3 mm for far points. This we take into account.

The temperature effect may contribute to more than 0.5 mm for quadrupole (shorter than dipole). For the present production conditions this seems to give a considerable contribution, that could be corrected.

For this effect we have a bias of the magnet positioning (magnets too low).

To have an idea of the errors for one measurement from one side we have taken the xxx??? (in this way we try to make sure that shape changes do not contribute)



1. Spool piece position calculation (industry data), evaluation of effect of saw tooth on positioning (CERN data)

2. Aperture: The degradation in the vertical plane of the so called geometry classes

is very sensitive. If the tolerances are tightened by only 0.15 mm all golden magnets degrade to silver!!! Where is really the magnet? Are the shifts in the correct direction?

5 10 15 20 25

0.2

0.4

0.6

0.8

1

h [0.01mm]h

v

fraction

0.01 mm

fraction

v [0.01 mm]

All degraded if 0.1 mm shift in GA in firm 2!!!



Dipoles of firm 1 tested during last 5 months of 2005, aperture 1



3290

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

0 5 10 15

Y [m]

dZ

[m

m]

DZ_CONN DZ_CONN_INT DZ_LYRE DZ_LYRE_INT

Saw Tooth Height

The “Y-mate” point should be

calculated for each point

measured from another side

by means of interpolation

3290

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

0 5 10 15

Y [m]

dZ

[m

m]

DZ_CONN DZ_LYRE

difference

Lj

Ci yy

Lj

Ci yy


I. Description of the problem 2Saw Tooth Height – Average

To calculate the average saw tooth height the area between the curves should be divided by the length on which the both points are known at each yi

yyS diffh

minmax

If the connection curve liesbelow the lyre one, the areais negative. We can sum upsigned or absolute values.

Since the points are evenly spread this differs from simple average by max 0.02 mm

— +


I. Description of the problem 2Average Tooth Height over Time

ITP20-GEO

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Jan-04 Apr-04 Aug-04 Nov-04 Feb-05 May-05 Sep-05 Dec-05 Mar-06

Measurement date at ITP20-GEO

[mm

]

ITP20-GEO

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5


[mm

]

Absolute

“With sign” WP08-FID

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5


[mm

]l

WP08-FID

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45


Measurement date at WP08-FID

[mm

]


I. Description of the problem 2Average Absolute Height: Firms

Step ITP15

ITP15 Firm 3

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

01-2004 08-2004 02-2005 09-2005 03-2006

ITP15 Firm 2

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

01-2004 08-2004 02-2005 09-2005 03-2006

ITP15 Firm 1

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

01-2004 08-2004 02-2005 09-2005 03-2006


I. Description of the problem 2Average Absolute Height: Firms

ITP20-GEO Firm 3

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Jan-04 Apr-04 Aug-04 Nov-04 Feb-05 May-05 Sep-05 Dec-05


[mm

]

ITP20-GEO Firm 2

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5


Measurement date at ITP20-GEO[m

m]

ITP20-GEO Firm 1

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5



[mm

] Step ITP20-GEO


I. Description of the problem 2Difference is not always Linear: Example 1

y = 0.0435x - 0.124

R2 = 0.7658

R2 = 0.9242

-0.4

-0.2

0

0.2

0.4

0.6

0.8

0 2 4 6 8 10 12 14 16

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0 2 4 6 8 10 12 14 16

DZ_CONN_INT DZ_LYRE_INT

For many magnets the difference in the middle is constant or decreasing when the global slope is positive.

Example: 3428 A1 WP08-FID

Diff > 0


I. Description of the problem 2Difference is not Linear: Example 3

Example: 1045 A2 Step WP08-FID

Unusual pattern

y = 0.049x - 0.4657

R2 = 0.7408

R2 = 0.9146

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0 2 4 6 8 10 12 14 16

-0.8-0.6

-0.4-0.2

00.20.4

0.60.8

11.2

0 2 4 6 8 10 12 14 16

DZ_CONN_INT DZ_LYRE_INT



Horizontal Plane

Whole production statisticsis very close to the simulation results*(G.Gubello et al. 2004)

Here p - slope, q – shift, h – tooth

* Vertical plane similar from recent modeling by Marco

STEP Height* average Height std Slope avg Slope std Shift avg Shift std

ITP15 0.083 0.050 -9.51E-08 7.04E-06 0.016 0.110

ITP20-GEO 0.085 0.048 9.33E-07 8.40E-06 0.011 0.112

WP08-FID 0.091 0.053 3.17E-06 6.91E-06 -0.016 0.112

Saw tooth criterion:


I. Description of the problem 2The Bundle

Arbitrary reference systems, chosen here to be the GA of one side

measurement


I. Description of the problem 2The BundleSaw tooth criterion:



Saw tooth criterion:



In industry: Where is mounted the spool piece? The best possible guess of the tube position is the “mean” of the point. GA is the best possible choice. We have to estimate the error on the spool piece position by the difference in the GA of the two measurements from the two sides.

“Best fit”At CERN: the spool piece is measured via an external point (end cover) so no problem with saw tooth. The effect is small for the aperture, impact has been evaluated by simulations by Marco la China.

GA on which the spool is mounted and measured, itp15bis. Itp20 just intermediate (for corrector)



0.2 m 0.2 m

Convection cell position

Linear interpolation from “knee” at 0.2 cm, from ends

Reference line for the correction

y

z 2D !!!

Crossover straight line from best fit and the 0.2 m boundary (rotation point)

Measurement from Connection Side Measurement from Non Connection

Side



))()((,, irefifitconnectioniorigicorr yzyzzz

Procedure proposed for the correction:

y

z

Connection side

))()((,, irefiionfitnonconnectiorigicorr yzyzzz Non Connection side

)(yzGA

)(yz fitconnection

)(yz ionfitnonconnect



)( ifitconnection yz

)( iref yz

y

z

iz correction



GA Shift

-0.4

-0.3

-0.2

-0.1

0

Shif t 10 Shif t 100

1. Why do we choose 0.2 m from the ends?

The position of the convection cell is difficult to estimate by analysis (very few measurement points). The value is chosen from MTM reports. We have made and extensive analysis of the impact of moving the position of the convection cell and the change in saw tooth between 0.1 and is less than for the largest saw tooth

GA Slope

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

Slope 10 Slope 100



2. Why do we make a linear interpolation of the measurement?

The measurement is not linear and often different from the nominal vertical shape due to gravity.

The linear interpolation is chosen due to the similarity with the GA construction which is a best fit of a plane (however 3D).

3. Why is the reference line taken between the two knee points?

We estimate that the two knee-points are the two last points where the data is not affected by the light deflection. So from these points onward we should superpose the two curves best fitted with straight lines.



We believe that we can treat the data so as to get a better idea of the magnet shape by compensating for the temperature effects

How to proceed to check this assumption?

1. Check the corrected value of the saw tooth (using the criteria described above). It should be small (comparable to the measurement errors for one measurement, from one side).

2. Compare shape at WP08 with shape at itp20, including position of end cover. If we can recover the shape at ITP20 by this method we believe the idea makes sense. Checks are made also for one case in industry where two measurements were made for magnet 2279.

3. A set of magnets have been chosen where the saw tooth is significant and where outliers (peaks in the measurements) have been excluded.



Stdev = 0.07 mm

MAGNET_NU,STEP 1105,WP08B-FID 1123,WP08C-FID 1135,WP08B-FID 1153,WP08B-FID 1154,WP08B-FID 1178,WP08B-FID 1211,WP08B-FID 1213,WP08B-FID 1221,WP08B-FID 1246,WP08C-FID 2056,WP08B-FID 2086,WP08B-FID 2096,WP08B-FID 2118,WP08B-FID

2133,WP08B-FID 2152,WP08B-FID 2195,WP08B-FID 2216,WP08B-FID 3035,WP08B-FID 3102,WP08B-FID 3152,WP08B-FID 3158,WP08B-FID 3203,WP08B-FID 3209,WP08B-FID 3238,WP08B-FID 3348,WP08B-FID 3392,WP08B-FID3395,WP08B-FID

Stable distance is chosen between Y = 1.4 m and Y = 13.8 m.

Outlier if > 6 sigma



Check the value of the saw tooth



Magnet shift1153 01154 02096 02152 03152 .13203 03209 03395 01178 .21221 01246 02133 -.253158 03392 02056 03348 01123 01213 01211 02216 03238 .152086 -.152118 0

The magnet should be shifted by 0.3 positive!!!

The magnet should be shifted by 0.2 positive!!!


)( ifitconnection yz

)( iref yz

y

z

iz correction


shifts


II. ANTIMATTER AND THE UNIVERSE

1933 Dirac’s Vision

“If we accept the view of complete symmetry between positive and negative electric charge so far as concerns the fundamental laws of Nature, we must regard it rather as an accident that the Earth (and presumably the whole solar system), contains a preponderance of negative electrons and positive protons. It is quite possible that for some of the stars it is the other way about, these stars being built up mainly of positrons and negative protons. In fact, there may be half the stars of each kind. The two kind of stars would both show exactly the same spectra, and there would be no way of distinguishing them by present astronomical methods.”

From his Nobel lecture (12 December 1933)

1) Symmetric Universe?

2) Where is the antimatter?

3) Antihydrogen spectrum?


I. History - Overview

1905Special relativity

1925Quantum Mechanics

1927Dirac Equation

1955Antiproton

1956-1980s: Scattering, annihilation,

Meson spectroscopy

1983-1996LEAR

1970sAccumulation + Cooling

2000-nowAntiproton Decelerator

1956Antineutron

1965Antideuteron

1978Anti-Tritium

1980s-now: W,Z, b,t physics

PrimordialAntimatter?Anti-Stars?

1932Positron

1948Positronium

Trapping

1970Anti-Helium-3

Technical developments

1996: Hot (v~c)Antihydrogen

1980s-nowColliders (SppS, Tevatron)

ColdAntihydrogen

1 saw tooth and remedies - elena wildner saw tooth elenawildner and natalia emelianenko at/mas the...

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