[PWGCF] Fix FT0 gain correction indexing in longRangeDihadronCor#14489

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MartijnLaarhoven wants to merge 1 commit intoAliceO2Group:masterfrom

MartijnLaarhoven:fix-ft0-gain-indexing-v3

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MartijnLaarhoven commented Jan 14, 2026

Use channel ID instead of array index for gain correction
Fixes mismatched amplitude corrections for remapped dead channels


          Fix FT0 gain correction indexing in longRangeDihadronCor

bd2491f

- Use channel ID instead of array index for gain correction
- Fixes mismatched amplitude corrections for remapped dead channels

Copilot AI review requested due to automatic review settings

January 14, 2026 22:13

MartijnLaarhoven requested review from alibuild, ariedel-cern, glromane, lauraser, lgraczykCern, otonvd, prchakra, shouqiye, victor-gonzalez and zchochul as code owners

January 14, 2026 22:13

github-actions bot added the pwgcf label

github-actions bot commented Jan 14, 2026

O2 linter results: ❌ 0 errors, ⚠️ 4 warnings, 🔕 0 disabled

github-actions bot changed the title ~~Fix FT0 gain correction indexing in longRangeDihadronCor~~ [PWGCF] Fix FT0 gain correction indexing in longRangeDihadronCor

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January 14, 2026 22:14

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Pull request overview

This PR attempts to fix FT0 gain correction indexing by using channel IDs instead of array indices, which should correct mismatched amplitude corrections for remapped dead channels. However, the PR contains critical unresolved merge conflicts that prevent it from compiling.

Changes:

Adds duplicate code blocks with merge conflict markers visible in the diff
Introduces temporary variables for mirrored amplitudes in the conflicting sections
Adds channel rejection checks in fillCorrelationsTPCFT0 function

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PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

Comment on lines +708 to +717

+              <<<<<<< Updated upstream
                         registry.fill(HIST("FT0Amp"), dead_id, ampl);
                         ampl = ampl / cstFT0RelGain[iCh];
                         registry.fill(HIST("FT0AmpCorrect"), dead_id, ampl);
+              =======
+                        float mirroredAmpl = ampl;
+                        float mirroredAmplCorrected = mirroredAmpl / cstFT0RelGain[iCh];
+                        registry.fill(HIST("FT0Amp"), dead_id, mirroredAmpl);
+                        registry.fill(HIST("FT0AmpCorrect"), dead_id, mirroredAmplCorrected);
+              >>>>>>> Stashed changes

Copilot AI Jan 14, 2026

Unresolved merge conflict in FT0A dead channel remapping code. The file contains Git conflict markers and duplicate code blocks that will prevent compilation. Resolve the merge conflict by choosing the appropriate version or merging the changes properly.

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PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

                         int dead_id = id + kFT0CInnerMirror;
+              <<<<<<< Updated upstream
                         registry.fill(HIST("FT0Amp"), dead_id, ampl);
                         ampl = ampl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

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PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

		@@ -679,6 +680,18 @@ struct LongRangeDihadronCor {
		registry.fill(HIST("FT0Amp"), dead_id, ampl);
		ampl = ampl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

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PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

                         registry.fill(HIST("FT0AmpCorrect"), dead_id, ampl);
+              =======
+                        float mirroredAmpl = ampl;
+                        float mirroredAmplCorrected = mirroredAmpl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

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PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

+                      } else if (id >= kFT0CRemapChannelStart && id <= kFT0CRemapChannelEnd) {
+                        int dead_id = id + kFT0COuterMirror;
+                        float mirroredAmpl = ampl;
+                        float mirroredAmplCorrected = mirroredAmpl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

Copilot uses AI. Check for mistakes.

PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

                         int dead_id = id - kFT0AOuterMirror;
+              <<<<<<< Updated upstream
                         registry.fill(HIST("FT0Amp"), dead_id, ampl);
                         ampl = ampl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

Copilot uses AI. Check for mistakes.

PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx

                         registry.fill(HIST("FT0AmpCorrect"), dead_id, ampl);
+              =======
+                        float mirroredAmpl = ampl;
+                        float mirroredAmplCorrected = mirroredAmpl / cstFT0RelGain[iCh];

Copilot AI Jan 14, 2026

The gain correction still uses array index iCh instead of channel ID. According to the PR description, this should use the channel ID (id or dead_id) to fix mismatched amplitude corrections for remapped channels. The cstFT0RelGain array has 208 elements indexed by channel ID (0-207), not by array position. This should be cstFT0RelGain[dead_id] to correctly apply the gain correction for the remapped channel.

Copilot uses AI. Check for mistakes.

Collaborator

alibuild commented Jan 14, 2026

Error while checking build/O2Physics/o2 for bd2491f at 2026-01-14 23:26:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:674:1: error: version control conflict marker in file
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:675:25: error: expected primary-expression before ')' token
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:683:1: error: version control conflict marker in file
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:685:41: error: 'mirroredAmpl' was not declared in this scope
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:694:1: error: version control conflict marker in file
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:708:1: error: version control conflict marker in file
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:709:25: error: expected primary-expression before ')' token
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:712:1: error: version control conflict marker in file
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:714:41: error: 'mirroredAmpl' was not declared in this scope
/sw/SOURCES/O2Physics/14489-slc9_x86-64/0/PWGCF/TwoParticleCorrelations/Tasks/longRangeDihadronCor.cxx:717:1: error: version control conflict marker in file
ninja: build stopped: subcommand failed.

Full log here.

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