Bose 2.2 User Manual download pdf (Page 58)

The precise determination of the function

(

) is the main goal of the calibration

procedure. However, to display the results in real physical parameters, we have to convert

the Feshbach current into a magnetic ﬁeld strength. Therefore, we have performed spec-

troscopy measurements on a thermal cloud for diﬀerent values

. For our settings of

the PI controller

, we obtain the scaling

dB/dI

= (2

429

004)

, where the value

= 0

−

20 is given in arbitrary units used in the Labview control program. Since the

measured center of the Feshbach resonance

FB,0

corresponds to the magnetic ﬁeld value

= 589.1 G [95], the magnetic ﬁeld is fully determined

Width of the Feshbach resonance

To evaluate the width of the Feshbach resonance at

= 589

, we have collected

the data of 14 calibrations of the scattering length. When calculating the mean value

and the standard deviation of the single measured widths, we obtain the width ∆

09)

for the FR. This value is slightly lower than the theoretical prediction

∆B

0,theo

= 1.7 G [95].

Analog output voltages of National Instruments cards:

(

= 0) = 0

(

= 20) = 10

Converted voltages on PI controller: DVsum(I

= 0) = 9.23 V and DVsum(I

= 20) = 9.96 V.

The minimum ﬁeld strength that we can reach is

min

(

= 0) = (577

, while the

maximum ﬁeld strength is B

max

= B(I

= 20) = (626.0 ± 0.2) G.

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Bose 2.2 User Manual Page 58

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