-------- Original Message --------
Subject: Analysis of measurement data from Solenoid without iron box
Date: Thu, 17 May 2001 11:44:24 -0700
From: Michael Barnes 
Organization: TRIUMF
To: Nathan Rodning 
CC: John Macdonald , drgill@triumf.ca,Ewart
Blackmore , Doug Evans 

Hi Nate,

This email is to let you know the results of an analysis of data,
measured in November 1998 by Doug Evans, for the E614 solenoid (not in
an iron box). The analysis has been carried out for data taken on the
central axis of the solenoid (X=0 & Y=0).
The two measurement data files analyzed are:
1) 111098.2 (serial plate facing south): this corresponds to -Zmagnet on
the attached plots [Doug tells me that the serial plate was upstream
(i.e. -Ztwist) for the measurements taken in the iron box]
2) 111898.2 (serial plate facing north). The "polarity" of Z coordinates
in file 111898.2 are w.r.t. to the position of the magnet mapping
equipment; in order to obtain  Zmagnet  the Z coordinate in 111898.2 was
multiplied by -1. Similarly the flux density was multiplied by -1.

In the four attached PostScript files:
a) "BG 111098.2" is the measured Bz flux density versus Zmagnet;
b) "BG 111098.2. Data flattened between -25.4cm & -25.4cm" is the
measured Bz flux density after the slope has been mathematically
removed. To remove the slope, the gradient (kG/cm) has been calculated
between -25.4cm & 25.4cm: a correction to each measured field value is
calculated by multiplying this slope by the corresponding Zmagnet
coordinate.
c) "BG 111898.2 [solenoid turned around]" is the measured Bz flux
density (multiplied by -1) versus Zmagnet;
d) "BG 111898.2 [solenoid turned around]. Data flattened between -25.4cm
& -25.4cm" is the measured Bz flux density after the slope has been
mathematically removed (see "b" for details).
e) "(BG 111098.2 - BG 111898.2)/2" is the average of curves "a" and "c"
(i.e. the average of the field before the slope is corrected for).

The above five curves are shown in files:
FullData.ps (Zmagnet range from -75cm to +75cm);
LimitData.ps (Zmagnet range from -55cm to +55cm);
+Z.ps (Zmagnet range from +55cm to +75cm);
-Z.ps (Zmagnet range from -55cm to -75cm);

In order to determine whether the coils are centered, w.r.t. to the
outer shell of the solenoid, the values of Zmagnet where the flux
density crosses 1.82kG (arbitrarily chosen value) have been noted:

Curve "BG 111098.2. Data flattened between -25.4cm & -25.4cm" crosses
1.82kG at Zmagnet of -73.75cm (see -Z.ps) and 74.52cm (see +Z.ps); this
infers that the coils are off center by approx. +0.39cm
[(74.52-73.75)/2].

"BG 111898.2 [solenoid turned around]. Data flattened between -25.4cm &
-25.4cm" crosses 1.82kG at Zmagnet of -74.13cm (see -Z.ps) and 74.79cm
(see +Z.ps); this infers that the coils are off center by approx.
+0.33cm [(74.79-74.13)/2].

"(BG 111098.2 - BG 111898.2)/2" crosses 1.82kG at Zmagnet of -73.90cm
(see -Z.ps) and 74.66cm (see +Z.ps); this infers that the coils are off
center by approx. +0.38cm [(74.66-73.90)/2].

(Note: the measurement data was taken in Z increments of 1 inch
[2.54cm]).

>From the above it appears that the coil was off-centre, w.r.t. to the
outer vacuum vessel, by a distance of approx. +0.35cm (in the direction
of +Zmagnet). The direction of the coil being off centre is consistent
with the direction of displacement (+Ztwist) of the recent measurements
in the iron box. However the magnitude of the displacement of the coil
is very different in the magnet box (approx. 2cm to 3cm)

Cheers,
Mike Barnes

Filename: LimitData.ps

Filename: FullData.ps

Filename: +Z.ps

Filename: -Z.ps

Created for the The Center for Subatomic Research E614 Project Projects Page.

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