An apparatus and a method for detecting particle beam characteristics are disclosed. In one embodiment, the apparatus may have a body including a first end and second end and at least one detector between the first and second ends. The apparatus may have a transparent state where a portion of the particles entering the apparatus may pass through the apparatus. The apparatus may also have a minimum transparency state where substantially all of the particles entering the apparatus may be prevented from passing through the apparatus and detected. Different transparency state may be achieved by rotating the apparatus or the detector contained therein. With the apparatus, it is possible to detect the beam properties such as the beam intensity, angle, parallelism, and a distribution of the particles in a particle beam.