Alpha Scans

Gas:

Isobutane at a pressureof 20 torr.

Voltages:

Magnet:

Set the magnet to scanfrom 265 to 185 Amperes, at a scan rate setting of 0.2.This corresponds to approximately 5 Amps/minute. A scan takes about 15 minutes.

241 Am Properties:

• 5.443 MeV 13%
• 5.486 MeV 85%

Experiments

Detector Position

k is a kinematical factor that can be calculated for a particular reaction, beam energy and lab angle. It is defined as (1/p) * dp/dtheta.

z is position (roughly in cm, arbitrary origin) of the detector along the reaction product trajectory. The second motor control/display unit sets z. The limits for the current detector box in z are 33.6 and 57.2. The others control the up/down degree of freedom, and the angle in the horizontal plane of the detector. The angle degree of freedom is necessary, since k has a noticiable momentum dependence, largely of first order in p. Only z is usually adjusted.

The formula is z = 55.5 + 56.7 × k. You can calculate "z" below after inputting "k" and pressing the calculate button below.

Biasing the Detector

Cathode and Grids

A graph is drawn below which interpolates between our usual settings for 20 torr and 250 torr. This should to first order give the right field profiles, though judgement should always be used. Also biases should be raised so as to keep fields reasonable at all times, and keep currents low.

Wire Biases