Detector ID encoding

LEGEND detectors IDs are variable-length strings, so their string representation is not ideal as an in-memory representation, for storage as binary tabular data and GPU memory. Therefore, the following 32-bit unsigned integer encoding should be used when writing detector IDs to files, it can also serve as an efficient in-memory representation.

Binary encoding

Encoding length: 4-byte unsigned integer value, stored as a 32-bit or 64-bit integer.

Format (nibbles): RT XX XX XY

• Reserved (R): 1 Nibble, always zero

• Type (T), 1 Nibble:

  • 0x0: reserved
  • 0x1: C (Coax HPGe)
  • 0x2: B (BEGe HPGe)
  • 0x3: P (PPC HPGe)
  • 0x4: V (ICPC HPGe)
  • 0x5: reserved
  • 0x6: reserved
  • 0x7: reserved
  • 0x8: reserved

* 0x9: S (SiPM)
* 0xa: PMT (PMT)
* 0xb: PULS
* 0xc: AUX
* 0xd: DUMMY
* 0xe: BSLN
* 0xf: MUON

• Serial-Number (XXXXX), 5 Nibbles, unsigned integer in binary form (not BCD).

• Sub-Serial-Number (Y), 1 Nibble, unsigned integer in binary form (not BCD):

  • For HPGe: Detector slice, 0 = A, 1 = B, 2 = C, ...
  • For SiPM: always 0
  • For PMT: always 0
  • For Pulser: 0 = PULSnn, 1 = PULSnnANA
  • For Dummy: always 0

String representation

• [B|C|P|V]nnnnn[A|B|C|D|M]: represent serial number with five digits in string
• Snnn: represent serial number with three digits in string
• PMTnnn: represent serial number with three digits in string
• PULSnn, PULSnnANA: represent serial number with two digits in string
• AUXnn: represent serial number with two digits in string
• DUMMYnn: represent serial number with two digits in string. Special case: legacy data may contain DUMMY0 to DUMMY9, with a single digit, it should be possible to parse these as well, but when converting integer to string representation, two digits should be used.
• BSLNnn: represent serial number with two digits in string
• MUONnn: represent serial number with two digits in string

Special cases:

• C00ANGn: Encode as R[C][f100n][0]
• C000RGn: Encode as R[C][f200n][0]

Test cases:

"B00000C" <-> 0x02000002
"B59231A" <-> 0x020e75f0
"C00000A" <-> 0x01000000
"C83847I" <-> 0x01147878
"C000RG4" <-> 0x01f20040
"C00ANG7" <-> 0x01f10070
"P94752A" <-> 0x03172200
"P00000K" <-> 0x0300000a
"V99999J" <-> 0x041869f9
"V98237P" <-> 0x0417fbdf
"S000" <-> 0x09000000
"S632" <-> 0x09002780
"S999" <-> 0x09003e70
"PMT000" <-> 0x0a000000
"PMT183" <-> 0x0a000b70
"PMT999" <-> 0x0a003e70
"PULS00" <-> 0x0b000000
"PULS00ANA" <-> 0x0b000001
"PULS99" <-> 0x0b000630
"PULS99ANA" <-> 0x0b000631
"AUX00" <-> 0x0c000000
"AUX99" <-> 0x0c000630
"DUMMY0" <-> 0x0d000000
"DUMMY00" <-> 0x0d000000
"DUMMY9" <-> 0x0d000090
"DUMMY09" <-> 0x0d000090
"DUMMY10" <-> 0x0d0000a0
"DUMMY99" <-> 0x0d000630
"BSLN00" <-> 0x0e000000
"BSLN99" <-> 0x0e000630
"MUON00" <-> 0x0f000000
"MUON99" <-> 0x0f000630
"C000RG4" <-> 0x01f20040
"C00ANG7" <-> 0x01f10070