diff --git a/Trigger/TrigValidation/TrigAnalysisTest/share/ref_RDOtoRDOTrig_mt1_build.ref b/Trigger/TrigValidation/TrigAnalysisTest/share/ref_RDOtoRDOTrig_mt1_build.ref
index a630bc33e2b354a576de77262758ae967ad99507..d4c3405d96c4b3c69c3273aab03fed48c77fb8d5 100644
--- a/Trigger/TrigValidation/TrigAnalysisTest/share/ref_RDOtoRDOTrig_mt1_build.ref
+++ b/Trigger/TrigValidation/TrigAnalysisTest/share/ref_RDOtoRDOTrig_mt1_build.ref
@@ -502,6 +502,9 @@ TrigSignatureMoniMT INFO -- #1651897827 Features
TrigSignatureMoniMT INFO HLT_noalg_L1J85 #166231461
TrigSignatureMoniMT INFO -- #166231461 Events 5 5 - - - - - - 5
TrigSignatureMoniMT INFO -- #166231461 Features - - - - - -
+TrigSignatureMoniMT INFO HLT_noalg_L1MBTS_1_EMPTY #4174355886
+TrigSignatureMoniMT INFO -- #4174355886 Events 0 0 - - - - - - 0
+TrigSignatureMoniMT INFO -- #4174355886 Features - - - - - -
TrigSignatureMoniMT INFO HLT_noalg_L1RD0_EMPTY #914660695
TrigSignatureMoniMT INFO -- #914660695 Events 0 0 - - - - - - 0
TrigSignatureMoniMT INFO -- #914660695 Features - - - - - -
diff --git a/Trigger/TrigValidation/TriggerTest/share/ref_data_v1Dev_build.ref b/Trigger/TrigValidation/TriggerTest/share/ref_data_v1Dev_build.ref
index 2cee756238739274c3cdba9d2991d19b153cfb29..001326b44345672c922cc06e5c77b91cb13268cf 100644
--- a/Trigger/TrigValidation/TriggerTest/share/ref_data_v1Dev_build.ref
+++ b/Trigger/TrigValidation/TriggerTest/share/ref_data_v1Dev_build.ref
@@ -502,6 +502,9 @@ TrigSignatureMoniMT INFO -- #1651897827 Features
TrigSignatureMoniMT INFO HLT_noalg_L1J85 #166231461
TrigSignatureMoniMT INFO -- #166231461 Events 20 20 - - - - - - 20
TrigSignatureMoniMT INFO -- #166231461 Features - - - - - -
+TrigSignatureMoniMT INFO HLT_noalg_L1MBTS_1_EMPTY #4174355886
+TrigSignatureMoniMT INFO -- #4174355886 Events 20 20 - - - - - - 20
+TrigSignatureMoniMT INFO -- #4174355886 Features - - - - - -
TrigSignatureMoniMT INFO HLT_noalg_L1RD0_EMPTY #914660695
TrigSignatureMoniMT INFO -- #914660695 Events 20 20 - - - - - - 20
TrigSignatureMoniMT INFO -- #914660695 Features - - - - - -
diff --git a/Trigger/TriggerCommon/TriggerMenuMT/python/HLTMenuConfig/Menu/LS2_v1.py b/Trigger/TriggerCommon/TriggerMenuMT/python/HLTMenuConfig/Menu/LS2_v1.py
index 1fb99d65fe69142098d718183742c7c431a8ea17..152b2bd1d76bf1b0ef72c8cb4c74d86e410f8f37 100644
--- a/Trigger/TriggerCommon/TriggerMenuMT/python/HLTMenuConfig/Menu/LS2_v1.py
+++ b/Trigger/TriggerCommon/TriggerMenuMT/python/HLTMenuConfig/Menu/LS2_v1.py
@@ -270,7 +270,9 @@ def setupMenu():
TriggerFlags.StreamingSlice.signatures = TriggerFlags.StreamingSlice.signatures() + [
ChainProp(name='HLT_noalg_mb_L1RD2_EMPTY', l1SeedThresholds=['FSNOSEED'], stream=['MinBias'], groups=MinBiasGroup),
ChainProp(name='HLT_noalg_zb_L1ZB', l1SeedThresholds=['FSNOSEED'], stream=['ZeroBias'], groups=ZeroBiasGroup),
+ ChainProp(name='HLT_noalg_L1MBTS_1_EMPTY', l1SeedThresholds=['FSNOSEED'], stream=['MinBias'], groups=MinBiasGroup), #ATR-21740
]
+
TriggerFlags.MonitorSlice.signatures = TriggerFlags.MonitorSlice.signatures() + [
]
diff --git a/Trigger/TriggerCommon/TriggerMenuMT/python/L1/Menu/Menu_MC_pp_v8.py b/Trigger/TriggerCommon/TriggerMenuMT/python/L1/Menu/Menu_MC_pp_v8.py
index 3989732ab3bd87a3ca45fe43d573652f2d4e0406..4aadf7d0802bba1bbe8e1c6d492be369f2b77ddd 100644
--- a/Trigger/TriggerCommon/TriggerMenuMT/python/L1/Menu/Menu_MC_pp_v8.py
+++ b/Trigger/TriggerCommon/TriggerMenuMT/python/L1/Menu/Menu_MC_pp_v8.py
@@ -240,7 +240,7 @@ def defineMenu():
# AFP
# MBTS
-
+ 'L1_MBTS_1_EMPTY',
#--------------------------------
# TOPO items
@@ -580,6 +580,8 @@ def defineMenu():
'L1_BCM_Wide_UNPAIRED_NONISO' : 161,
'L1_BCM_AC_UNPAIRED_ISO' : 163,
+ 'L1_MBTS_1_EMPTY' : 164,
+
'L1_EM20VH_3J20' : 26,
'L1_MU10_3J20' : 173,