IceTop Pulse Processing

WG Tech Lead: Katherine Rawlins (krawlins@alaska.edu)

Executive Summary

Before the IceTop filters are applied, there is a number of pulse-processing steps unique to IceTop. There are two different forms of “calibration” of IceTop tank signals. One is “VEMCal”, which converts pulse charges from “raw units” to units of Vertical Equivalent Muons (VEM). The other is “SLCCal”, which makes an adjustment to the charge measurements of IceTop SLC (single-tank) hits only.

../../_images/slide_in_the_north.png

The graphic above is one of the slides from a talk given to the ICC on 2/28/2023: [1], which has more detail about the “old” way of doing all of this, and why it was bad.

All of the calibration constants should be in the GCD file before this processing begins. In particular, the VEMCal constants should live in the “I3Calibration” object in the C-frame, and the SLCCal constants should live in a separate container (called an “I3IceTopSLCCalibrationCollection”) which is also in the C-frame.

The Individual Steps

  1. Split the IceTop “DST Pulses” into HLC and SLC pulses separately. All these pulses are in “raw units”.

  2. Apply the “SLCCal” calibration to the SLC pulses only.

  3. Apply “VEMCal” calibration to both sets of pulses: SLC and HLC. Now the pulses are in units of “VEM”.

  4. Apply the “TankPulseMerger” to both sets of pulses. This combines the high-gain and low-gain pulses (if both exist) into one set of pulses which represents the light seen in the tank overall.

  5. Perform “Cluster Cleaning”. The module that does this is also a “Splitter”, which produces P-frames named “IceTopSplit”.

The IceTop filters (see IceTop and Cosmic Ray Filters) are now ready to be run. They will run on each “IceTopSplit” P-frame. Most of the filters look at the HLC pulse series in that split, called the “CleanedIceTopHLCTankPulses”.

The SLC pulses are not used for any filters, at least, not at the time of this writing. However, it is convenient to the CR-WG to perform these calibration steps for the SLC’s alongside when they are run for the HLC’s. In particular, the “SLCCal” constants are measured in raw charge units by pfmonitoring, so it makes sense to apply that calibration first, while the pulses are still in raw charge units.

Frame Objects Produced

In the Q-frame, Steps 1-4 will add the following objects:

  • IceTopHLCTankPulses

  • IceTopSLCTankPulses

  • TankPulseMergerExcludedTanks

  • TankPulseMergerExcludedSLCTanks

In the IceTopSplit P-frame, Step 5 will add the following objects:

  • CleanedIceTopHLCTankPulses

  • ClusterCleaningExcludedTanks

References