Cosmic ray test stand setup

Setup

The cosmic ray test stand consists of two planes of scintillator paddles separated vertically by about 150cm. Each plane has 6 paddles. Each paddle is about 150cm long and about 20cm wide with a thickness of about 12mm. Both ends are equipped with a trapezoidal light guide and read out using a PMT XP2261. The HV is supplied by a CAEN 1527 main frame. The analog signals from the PMT are connected to a discriminator CAMAC LeCroy 4416. The 16 channel discriminator output is connected to a CAMAC LeCroy 4516 three fold logic unit to form the left-right coincidence for each paddle. The paddles from the TOP plane are the OR of the first 8 channels and the paddles from the BOTTOM plane are the OR of the second 8 channels as provided by two Lemo rear pannel outputs of the 4516. The coincidence between the TOP and BOTTOM paddles forms the trigger for the DAQ. As example the time difference between left and right of the first paddle in the TOP plane is shown here:

Note: the mean of the histogram is not exactly zero because there is no relative timing calibration done. Also, the edges of the histrogram are not very sharp because only leading edge discriminators are used and no walk correction has been applied. Using an average light speed of 16cm/ns to calculated the hit position along the paddle from the time difference yields the position historgram as follows: