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計測機器 EG&G ORTEC 463のPDF 操作・サービスマニュアルをオンラインで閲覧またはダウンロードできます。EG&G ORTEC 463 20 ページ。 Constant fraction discriminator

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rise time of <2 nsec and an amplitude of 10 V, the 463

walk should be tested for the range of 10 V to 100 mV.

Be careful when making this measurement to consider the

Tektronix Attenuator characteristics. It is not uncommon

for an insertion delay variation of +100 psec to exist

in the attenuator. Verify the delay consistency of the

attenuator before making the walk test, since 100 psec

is equivalent to <1/8-inch difference in signal path length

and is l ikely to exist for most attenuator units.

Na! Mode This test is identical to the procedure outlined

for Scint/SB mode except that the rise time of the signal

to the 463 should be about 5 nsec to simulate more

closely the signal from a Nal scintillator. The walk should

not exceed +0.5 nsec in this mode for a range of input pulse

heights from 10 V to 100 mV.

Walk Correction

If the unit fails to meet the walk test as

outlined above, a correction can be made. This adjustment

has been made at the factory and should not normally be

necessary unless some components have been replaced due

to failure. Use the following procedure:

1. Connect the 463 into the system shown in Fig. 6.2 and

set the Tektronix 50J2 Attenuator for XI. Move the cable

for the osci l loscope input signal to TPI on the top of the

463 and use a X10 attenuated probe.

2. Adjust R45 clockwise until the signal is similar to that

of Fig. 6.3a.

3. Adjust R45 counterclockwise until the signal is similar

to that of Fig. 6.3b.

4. Adjust R45 clockwise again until the signal at TPI is

correct as shown in Fig. 6.3c.

This provides a first-order adjustment and is usually

sufficient for proper walk characteristics. If a finer adjust

ment is necessary to minimize the walk, use the exact

system in Fig. 6.2. Set the attenuator to X50 and adjust

R45 (less than +1 turn) so that the time walk is zero.

After this adjustment the 463 should meet the walk test

suggested for al l three modes.

0 1 1 1

1 1 N

- /

1 1 1 1

-tHT

rt t r 11 1 1

1 1 1 1

1 M 1

1 1 1 1

(a) R45 Too Far Clockwise

(b) R45 Too Far Counterclockwise

1 1 1 1

1 1 1 r

M 41

1 1 1 1

4444-

4444

1 1 1 1

Vert.

0.5 V

/div

Horiz. 5 nsec/div

Fig. 6.3. Effect of Walk Adjustment In the ORTEC 463.