Overview

The main eDISK window consist of two parts. The large graphics display on the left and the Kinematics Window on the right. The latter is a dockable window meaning it can be detached and reattached to the main window. In it all the relevant DIS event kinematics is shown. When you changed one number all the others are re-calculated online. The schematic event display reflects the event kinematics. The status bar on the bottom of the main window reflects the validity of the current event kinematics.

Schematic Event Display:

The graphics window shows a schematic event display that reflects the parameters shown in the Kinematics Window. The red and blue arrows depict the incoming electron and proton beam directions, respectively. The red line shows the outgoing (scattered) electron, the dark blue line the outgoing quark. The length of the electron and quark line are scaled as follows: the higher energetic one of the two is scaled to full length, the smaller one is scaled to reflect the ratio of energies. For example, if the quark has an energy of 10 GeV and the electron of 5 GeV, the quark line is drawn at maximum length and the electron lines with half of the quark line length. The scattering angles are drawn following the convention explained in Units and Conventions. The circle around the vertex is divided in 5 degree bins. It's only purpose is to aid the eye.

There are two sets of parameters shown in the Kinematics Window: (i) beam parameters and (ii) DIS kinematics. At startup the kinematic parameters are set to some arbitrary values. Here are the details:

Beam Parameters:

You can enter the electron and proton beam energy at any time. The center-of-mass energy is updated instantaneously and with it all other parameters (DIS event parameters) that depend on it. You cannot change the center-of-mass energy directly.

DIS Kinematics:

The kinematics of an DIS event is fully determined when 2 parameters are defined. The combo box on top of this panel lets you select which ones you want to modify. The fields that can be edited turn blue. All the others remain black and are read-only that is they cannot be changed interactively. They are updated the moment you change one of the blue fields. An exception are v (nu) and W2 which are read-only all the time.

If the parameters you enter are out of bounds, i.e., the internal calculation of at least one of the fields fails, the event is not drawn and the status bar shows an error message. The variables shown in the text fields are meaningless at that point.

For details on the various kinematic variables see DIS Kinematics.

Alternative ways of changing parameters:

Alternatively one can use the mouse to alter the electron or quark scattering energy and or angle. Select the tip of the red (electron) or blue (quark) line with a left mouse click and move it around (holding the mouse button pressed). When selecting the quark or electron the combo box in the DIS Event Kinematics window does change to the referring mode.