{'fraction_non_alphanumeric': 0.03212576896787423, 'fraction_numerical': 0.012987012987012988, 'mean_word_length': 4.343065693430657, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
5. Measurement and Control of Beam Characteristics

In accelerators the extraction of the charged particles and further beam handling is done by means of magnetic or electric fields. The overall operation and its constancy in time has to be checked periodically about twice a year and at least after each repair of the accelerator or after changes in important parts. A more frequent (monthly) control is recommended if electronic equipment is used which may change with time. All the recommended test measurements can be done with the simple but standardized equipment shown in Figure 5.1 (Pohlit, 1965). A holder, H, for absorber plates, P, ( 30 cm X 30 cm) is constructed of angle iron. This holder rests on and is fastened to a plate. On one side, in front of this holder, a flat transmission ionization chamber can be installed as an accurate monitor, M. If this monitor is not required for a particular measurement, the whole device can be rotated through an angle of 90 degrees on a suitable support. The holder plate is fixed with two screws, S1, and S2, on a table, T. One screw, S1, is in the center of the holder plate so that the point is fixed during rotation of the holder. The second screw, S2, is eccentrically located on the plate and, when in place, provides one of two orientations of the holder. If, as described in section 5.2, other directions have to be used, an indication of the angle between the holder, H, and the table, T, is provided.