-- Obsolete -- Polarizer Test, April 19 - 23, 2008

by Phil Levy

Unlike all previous Polarizer operations, we will be polarizing an ion beam directly, without the complications of neutralizer and reionizer cells.

The goal of the test is to polarize ¹¹Be⁺, transport it to the BNQR and BNMR facilities and optimize the observed beta decay asymmetry. The Polarizer has been modified from its usual alkali-beam running condition as follows:

1. The Na cell and its thermocouples, the He cell and deflector plate ILE2:DEF15C have been removed.

2. A drift tube 2.0 m in length has been placed along the Polarizer axis.

3. The deceleration electrodes at the entrance to the Polarizer are matched by a new set of acceleration electrodes at the exit.

4. The laser is frequency-doubled into the ultraviolet (313 nm).

5. Large rectangular magnetic field (~10 gauss) coils have been added downstream of the Polarizer.

The modifications enable us to tune the energy of a 28.00 keV ¹¹Be⁺ beam using the usual deceleration electrodes, to maintain that energy over the drift tube length while the beam is optically pumped, and to accelerate the beam back to its original energy at the exit of the Polarizer. The electrical layout is shown in Fig. 1.

Tuning procedure:

The usual methods of ion beam tuning are to be used. Before beginning, ensure that the following are OFF:

ILE2:BIAS15

ILE2:BIASTUBE

ILE2:SOL15B

ILE2:DEF15C

The following must be ON:

ILE2:SOL15A @ 5 amps (octagonal coils 1 – 8, see attached Fig. 2)

Rectangular coils 11 – 12 @ 170 amps (manually controlled power supplies near BNQR will be operated by experimenters)

Circular coils 14 – 16 @ 10 amps (manually controlled power supply near BNQR will be operated by experimenters)

A good tune will have more than 80% transmission through the Polarizer.