How to investigate helicity analysis issues
From SBS wiki
The helicity bit as presented in the T tree currently depends upon the helicity scalers in both the SBS and LHRS crates and the helicity bits read in the FADCs in both crates. If there is an inconsistency in the data, the reported helicity is set to zero. When this happens, the tree variable "scalhel.errcode" indicates the sort of inconsistency as described in the table below.
| Hexcode | Decimal value | Meaning |
|---|---|---|
| 0x4 | 4 | The scaler helicity bits don't match the prediction of the reported helicity; we need to regenerate the seed |
| 0x8 | 8 | Too many events were in the pattern |
| 0x10 | 16 | Not enough bits in the seed value yet to predict the reported helcity |
| 0x01000000 | 16777216 | The helicity scaler rings have a mismatch between the LHRS and SBS crates. |
| 0x10000000 | 268435456 | The FADC helicity bits are mismatched between the LHRS and SBS. |
| 0x20000000 | 536870912 | Mismatch between FADC helicity bit and value expected from predictor |
| 0x40000000 | 1073741824 | Mismatch between FADC pattern sync bit and value expected from predictor |
| 0x80000000 | 2147483648 | Event is in the Tsettle period |
