- High magnetic field strength in order to achieve a high cyclotron frequency of the stored ions. Most systems presently employed for mass measurements have a 6-7 Tesla field. Going to higher fields increases the achievable precision and reduces the measurement time.
- Good field homogeneity and field stability. This is the prerequisite for reducing systematic errors in the mass determination.
- Room temperature bore. This eases ion transfer into and extraction from the trap. It also makes the trap alignment easier.
The LEBIT magnet is a persistent-mode 9.4 T super-conducting system with horizontal room-temperature bore. The system has an active shield for the reduction of the effect of external field changes.
The system has been built by Cryomagnetics, Inc 1006 Alvin Weinberg Drive Oak Ridge, TN 37830 http://www.cryomagnetics.com (see specifications below)
|
Magnet: |
Central
magnetic field |
9.4
Tesla |
|
|
Homogeneity
|
<
1 ppm in cylinder volume 2cm diameter and 4 cm long (estimated <10 ppb
over volume 2 mm diameter 4 mm long) |
|
|
|
|
|
|
Stability |
<
20 ppb/h |
|
|
10
Gauss line from center |
»1
m radially and on axis |
| External field shielding factor | >250 | |
|
|
|
|
|
Cryostat: |
Length
of bore |
1092
mm |
|
|
Clear
bore diameter |
128
mm |
|
|
Liquid
Helium consumption |
<
100 ml/h |
|
|
Liquid
Helium refill every |
>
80 days |
|
|
Liquid
Nitrogen consumption |
<
300 ml/h |
|
|
Liquid
Nitrogen refill every |
>
27 days |