diff --git a/CMakeLists.txt b/CMakeLists.txt
index fa51196..60071c6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -202,9 +202,11 @@ set(BxDecay0_HEADERS
   bxdecay0/Sb125.h
   bxdecay0/Sb126.h
   bxdecay0/Sb133.h
-  # bxdecay0/Sc44.h # Added from 2025-12-XX
+  bxdecay0/Sc44.h # Added Sc44 and Sc44m from 2025-12-16
+  bxdecay0/Sc44m.h
   bxdecay0/Sc48.h
   bxdecay0/Se76low.h
+  bxdecay0/Se83.h # Added from 2025-12-16
   bxdecay0/Sm148low.h
   bxdecay0/Sm150low.h
   bxdecay0/Sn114low.h
@@ -392,9 +394,11 @@ set(BxDecay0_SOURCES
   bxdecay0/Sb125.cc
   bxdecay0/Sb126.cc
   bxdecay0/Sb133.cc
-  # bxdecay0/Sc44.cc # Added from 2025-12-XX
+  bxdecay0/Sc44.cc # Added Sc44 and Sc44m from 2025-12-10
+  bxdecay0/Sc44m.cc
   bxdecay0/Sc48.cc
   bxdecay0/Se76low.cc
+  bxdecay0/Se83.cc # Added from 2025-12-16
   bxdecay0/Sm148low.cc
   bxdecay0/Sm150low.cc
   bxdecay0/Sn114low.cc
@@ -563,8 +567,10 @@ if(BUILD_TESTING)
     bxdecay0/testing/test_bb_utils.cxx
     bxdecay0/testing/test_bb.cxx
     bxdecay0/testing/test_genbbsub.cxx
-    # bxdecay0/testing/test_Sc44.cxx # Added from 2025-12-XX
+    bxdecay0/testing/test_Sc44.cxx # Added Sc44 and Sc44m from 2025-12-16
+    bxdecay0/testing/test_Sc44m.cxx
     bxdecay0/testing/test_Ga68.cxx # Added from 2025-12-05
+    bxdecay0/testing/test_Se83.cxx # Added from 2025-12-16
     bxdecay0/testing/test_decay0_generator.cxx
     bxdecay0/testing/test_event_reader.cxx
     )
diff --git a/bxdecay0/Ga68.cc b/bxdecay0/Ga68.cc
index 4940c30..2dd36a9 100644
--- a/bxdecay0/Ga68.cc
+++ b/bxdecay0/Ga68.cc
@@ -66,7 +66,7 @@ namespace bxdecay0 {
     
     // Three possible β⁺ decay modes
     if (pbeta <= 0.000285) {
-      decay0_beta(prng_, event_, 1.8991, -30, 0., 0., t);
+      decay0_beta(prng_, event_, 0.2432, -30, 0., 0., t);
       goto label_1656;
     }
     if (pbeta <= 1.190) {
@@ -74,7 +74,7 @@ namespace bxdecay0 {
       goto label_1077;
     }
     if (pbeta <= 88.9103) {
-      decay0_beta(prng_, event_, 0.2432, -30, 0., 0., t);
+      decay0_beta(prng_, event_, 1.8991, -30, 0., 0., t);
       goto label_10000;
     }
     // Six electron-capture processes
@@ -98,6 +98,7 @@ namespace bxdecay0 {
       decay0_gamma(prng_, event_, 0.01, 0., 0., t);
       goto label_1077;
     }
+    decay0_gamma(prng_, event_, 0.01, 0., 0., t);
     goto label_10000;
 
     label_2822:
diff --git a/bxdecay0/Sc44.cc b/bxdecay0/Sc44.cc
new file mode 100644
index 0000000..8d093c9
--- /dev/null
+++ b/bxdecay0/Sc44.cc
@@ -0,0 +1,119 @@
+// Copyright 1995-2016 V.I. Tretyak
+// Copyright 2011-2017 F. Mauger
+//
+// This program is free software: you  can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free  Software Foundation, either  version 3 of the  License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+// Ourselves:
+#include <bxdecay0/Sc44.h>
+
+// Standard library:
+#include <cmath>
+#include <sstream>
+#include <stdexcept>
+
+// This project:
+#include <bxdecay0/PbAtShell.h>
+#include <bxdecay0/alpha.h>
+#include <bxdecay0/beta.h>
+#include <bxdecay0/beta1.h>
+#include <bxdecay0/beta2.h>
+#include <bxdecay0/beta_1fu.h>
+#include <bxdecay0/electron.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/gamma.h>
+#include <bxdecay0/i_random.h>
+#include <bxdecay0/nucltransK.h>
+#include <bxdecay0/nucltransKL.h>
+#include <bxdecay0/nucltransKLM.h>
+#include <bxdecay0/nucltransKLM_Pb.h>
+#include <bxdecay0/pair.h>
+#include <bxdecay0/particle.h>
+#include <bxdecay0/positron.h>
+
+namespace bxdecay0 {
+
+  void Sc44(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_)
+  {
+    double t;
+    double tdlev;
+    double p;
+    double pbeta;
+    double tclev;
+    double thlev;
+    double thnuc;
+    // Scheme of Sc44 decay (National Nuclear Data Center (NNDC), Brookhaven National Laboratory).
+    // levels in keV.
+    // Input : tcnuc_ - time of creation of nucleus (sec)
+    // Output: tdnuc_ - time of decay of nucleus (sec)
+    // // common/genevent/tevst,npfull,npgeant(100),pmoment(3,100),// ptime(100).
+    // VIT, 7.05.1998
+    thnuc  = 1.45512e+04;
+    tdnuc_ = tcnuc_ - thnuc / std::log(2.) * std::log(prng_());
+    tclev  = 0.;
+    pbeta  = 100. * prng_();
+    
+    // One possible β⁺ decay mode
+    if (pbeta <= 94.27) {
+      decay0_beta(prng_, event_, 1.4737, -20, 0., 0., t);
+      goto label_1157;
+    }
+    // Three electron-capture processes
+    if (pbeta <= 94.2744) {
+      decay0_gamma(prng_, event_, 0.04, 0., 0., t);
+      goto label_3302;
+    }
+    if (pbeta <= 95,293) {
+      decay0_gamma(prng_, event_, 0.04, 0., 0., t);
+      goto label_2657;
+    }
+    decay0_gamma(prng_, event_, 0.04, 0., 0., t);
+    goto label_1157;
+
+    label_3302:
+      thlev = 35e-15;
+      p  = 100. * prng_();
+      if (p <= 72.55) {
+        decay0_nucltransK(prng_, event_, 2.14442, 0.00404, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1157;
+      }
+      decay0_nucltransK(prng_, event_, 3.30133, 0.00404, 9.3e-6, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+      
+
+    label_2657:
+      thlev = 30e-15;
+      p  = 100. * prng_();
+      if (p <= 89.0) {
+        decay0_nucltransK(prng_, event_, 1.4995, 0.00404, 3.1e-5, 0.0, tclev, thlev, tdlev);
+        goto label_1157;
+      }
+      decay0_nucltransK(prng_, event_, 2.6564, 0.00404, 1.34e-5, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_1157:
+      thlev = 2.95e-12;
+      decay0_nucltransK(prng_, event_, 1.157, 0.00404, 6.0e-5, 0.0, tclev, thlev, tdlev);
+
+    label_10000:
+      return;
+  
+}
+  // end of Sc44.f
+
+} // end of namespace bxdecay0
+
+// end of Sc44.cc
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/Sc44.h b/bxdecay0/Sc44.h
new file mode 100644
index 0000000..814847a
--- /dev/null
+++ b/bxdecay0/Sc44.h
@@ -0,0 +1,17 @@
+#ifndef BXDECAY0_SC44_H
+#define BXDECAY0_SC44_H
+
+namespace bxdecay0 {
+
+  class i_random;
+  class event;
+
+  void Sc44(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_);
+
+} // end of namespace bxdecay0
+
+#endif // BXDECAY0_SC44_H
+
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/Sc44m.cc b/bxdecay0/Sc44m.cc
new file mode 100644
index 0000000..7af59ae
--- /dev/null
+++ b/bxdecay0/Sc44m.cc
@@ -0,0 +1,102 @@
+// Copyright 1995-2016 V.I. Tretyak
+// Copyright 2011-2017 F. Mauger
+//
+// This program is free software: you  can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free  Software Foundation, either  version 3 of the  License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+// Ourselves:
+#include <bxdecay0/Sc44m.h>
+
+// Standard library:
+#include <cmath>
+#include <sstream>
+#include <stdexcept>
+
+// This project:
+#include <bxdecay0/PbAtShell.h>
+#include <bxdecay0/alpha.h>
+#include <bxdecay0/beta.h>
+#include <bxdecay0/beta1.h>
+#include <bxdecay0/beta2.h>
+#include <bxdecay0/beta_1fu.h>
+#include <bxdecay0/electron.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/gamma.h>
+#include <bxdecay0/i_random.h>
+#include <bxdecay0/nucltransK.h>
+#include <bxdecay0/nucltransKL.h>
+#include <bxdecay0/nucltransKLM.h>
+#include <bxdecay0/nucltransKLM_Pb.h>
+#include <bxdecay0/pair.h>
+#include <bxdecay0/particle.h>
+#include <bxdecay0/positron.h>
+
+namespace bxdecay0 {
+
+  void Sc44m(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_)
+  {
+    double t;
+    double tdlev;
+    double p;
+    double pbeta;
+    double tclev;
+    double thlev;
+    double thnuc;
+    // Scheme of Sc44m decay (National Nuclear Data Center (NNDC), Brookhaven National Laboratory).
+    // levels in keV.
+    // Input : tcnuc_ - time of creation of nucleus (sec)
+    // Output: tdnuc_ - time of decay of nucleus (sec)
+    // // common/genevent/tevst,npfull,npgeant(100),pmoment(3,100),// ptime(100).
+    // VIT, 7.05.1998
+    thnuc  = 2.10996e+05;
+    tdnuc_ = tcnuc_ - thnuc / std::log(2.) * std::log(prng_());
+    tclev  = 0.;
+    pbeta  = 100. * prng_();
+    
+    // IT to Sc44
+    if (pbeta <= 98.77) {
+      decay0_nucltransK(prng_, event_, 0.271251, 0.005, 0.14, 0., tclev, thlev, tdlev);
+      return;
+    }
+
+    // Electron-capture process
+    decay0_gamma(prng_, event_, 0.04, 0., 0., t);
+    goto label_3285;
+
+    label_3285:
+      thlev = 13.3e-12;
+      decay0_nucltransK(prng_, event_, 1.0019, 0.00404, 9.3e-6, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+      
+
+    label_2283:
+      thlev = 1.9e-12;
+      decay0_nucltransK(prng_, event_, 1.1261, 0.00404, 1.34e-5, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_1157:
+      thlev = 2.95e-12;
+      decay0_nucltransK(prng_, event_, 1.157, 0.00404, 6.0e-5, 0.0, tclev, thlev, tdlev);
+
+    label_10000:
+      return;
+  
+}
+  // end of Sc44m.f
+
+} // end of namespace bxdecay0
+
+// end of Sc44m.cc
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/Sc44m.h b/bxdecay0/Sc44m.h
new file mode 100644
index 0000000..bc9dba0
--- /dev/null
+++ b/bxdecay0/Sc44m.h
@@ -0,0 +1,17 @@
+#ifndef BXDECAY0_SC44M_H
+#define BXDECAY0_SC44M_H
+
+namespace bxdecay0 {
+
+  class i_random;
+  class event;
+
+  void Sc44m(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_);
+
+} // end of namespace bxdecay0
+
+#endif // BXDECAY0_SC44M_H
+
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/Se83.cc b/bxdecay0/Se83.cc
new file mode 100644
index 0000000..e5f02dc
--- /dev/null
+++ b/bxdecay0/Se83.cc
@@ -0,0 +1,249 @@
+// Copyright 1995+3516 V.I. Tretyak
+// Copyright 2011+3517 F. Mauger
+//
+// This program is free software: you  can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free  Software Foundation, either  version 3 of the  License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+// Ourselves:
+#include <bxdecay0/Se83.h>
+
+// Standard library:
+#include <cmath>
+#include <sstream>
+#include <stdexcept>
+
+// This project:
+#include <bxdecay0/PbAtShell.h>
+#include <bxdecay0/alpha.h>
+#include <bxdecay0/beta.h>
+#include <bxdecay0/beta1.h>
+#include <bxdecay0/beta2.h>
+#include <bxdecay0/beta_1fu.h>
+#include <bxdecay0/electron.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/gamma.h>
+#include <bxdecay0/i_random.h>
+#include <bxdecay0/nucltransK.h>
+#include <bxdecay0/nucltransKL.h>
+#include <bxdecay0/nucltransKLM.h>
+#include <bxdecay0/nucltransKLM_Pb.h>
+#include <bxdecay0/pair.h>
+#include <bxdecay0/particle.h>
+#include <bxdecay0/positron.h>
+
+namespace bxdecay0 {
+
+  void Se83(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_)
+  {
+    double t;
+    double tdlev;
+    double p;
+    double pbeta;
+    double tclev;
+    double thlev;
+    double thnuc;
+    // Scheme of Se83 decay (National Nuclear Data Center (NNDC), Brookhaven National Laboratory).
+    // levels in keV.
+    // Input : tcnuc_ - time of creation of nucleus (sec)
+    // Output: tdnuc_ - time of decay of nucleus (sec)
+    // // common/genevent/tevst,npfull,npgeant(100),pmoment(3,100),// ptime(100).
+    // VIT, 7.05.1998
+    thnuc  = 70.1;
+    tdnuc_ = tcnuc_ - thnuc / std::log(2.) * std::log(prng_());
+    tclev  = 0.;
+    pbeta  = 100. * prng_();
+    
+    // 11 possible β⁺ decay modes
+    if (pbeta <= 0.095) {
+      decay0_beta(prng_, event_, 0.811, +35, 0., 0., t);
+      goto label_3091;
+    }
+    if (pbeta <= 0.095+0.21) {
+      decay0_beta(prng_, event_, 1.092, +35, 0., 0., t);
+      goto label_2810;
+    }
+    if (pbeta <= 0.095+0.21+18.6) {
+      decay0_beta(prng_, event_, 1.850, +35, 0., 0., t);
+      goto label_2052;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07) {
+      decay0_beta(prng_, event_, 1.986, +35, 0., 0., t);
+      goto label_1916;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63) {
+      decay0_beta(prng_, event_, 2.242, +35, 0., 0., t);
+      goto label_1660;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63+0.36) {
+      decay0_beta(prng_, event_, 2.848, +35, 0., 0., t);
+      goto label_1054;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63+0.36+33.2) {
+      decay0_beta(prng_, event_, 2.871, +35, 0., 0., t);
+      goto label_1031;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63+0.36+33.2+12.8) {
+      decay0_beta(prng_, event_, 2.914, +35, 0., 0., t);
+      goto label_988;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63+0.36+33.2+12.8+0.14) {
+      decay0_beta(prng_, event_, 3.035, +35, 0., 0., t);
+      goto label_867;
+    }
+    if (pbeta <= 0.095+0.21+18.6+2.07+2.63+0.36+33.2+12.8+0.14+0.1) {
+      decay0_beta(prng_, event_, 3.103, +35, 0., 0., t);
+      goto label_799;
+    }
+    decay0_beta(prng_, event_, 3.902, +35, 0., 0., t);
+    goto label_10000;
+
+    label_3091:
+      thlev = 0.0;
+      p  = 100. * prng_();
+      if (p <= 55.0) {
+        decay0_nucltransK(prng_, event_, 2.7347, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 3.0913, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+      
+
+    label_2810:
+      thlev = 0.0;
+      p  = 100. * prng_();
+      if (p <= 68.8) {
+        decay0_nucltransK(prng_, event_, 1.779, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1031;
+      }
+      if (p <= 62.6) {
+        decay0_nucltransK(prng_, event_, 2.4532, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 2.8099, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_2052:
+      thlev = 0.0;
+          p  = 100. * prng_();
+      if (p <= 0.64) {
+        decay0_nucltransK(prng_, event_, 0.3915, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1660;
+      }
+      if (p <= 7.1) {
+        decay0_nucltransK(prng_, event_, 0.9976, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1054;
+      }
+      p  = 100. * prng_();
+      if (p <= 18.5) {
+        decay0_nucltransK(prng_, event_, 1.0208, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1031;
+      }
+      if (p <= 37.3) {
+        decay0_nucltransK(prng_, event_, 1.1163, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_988;
+      }
+      p  = 100. * prng_();
+      if (p <= 41.5) {
+        decay0_nucltransK(prng_, event_, 1.6947, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 2.0515, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_1916:
+      thlev = 0.0;
+      if (p <= 9.7) {
+        decay0_nucltransK(prng_, event_, 0.8845, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_1031;
+      }
+      p  = 100. * prng_();
+      if (p <= 42.5) {
+        decay0_nucltransK(prng_, event_, 1.1163, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_799;
+      }
+      decay0_nucltransK(prng_, event_, 1.5589, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_357;
+
+    label_1660:
+      thlev = 0.0;
+      if (p <= 30.9) {
+        decay0_nucltransK(prng_, event_, 1.3033, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_799;
+      }
+      decay0_nucltransK(prng_, event_, 1.6601, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_1054:
+      thlev = 0.0;
+      decay0_nucltransK(prng_, event_, 1.0538, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_1031:
+      thlev = 0.0;
+      if (p <= 0.88) {
+        decay0_nucltransK(prng_, event_, 0.2315, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_799;
+      }
+      p  = 100. * prng_();
+      if (p <= 42.3) {
+        decay0_nucltransK(prng_, event_, 0.674, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 1.0306, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_988:
+      thlev = 0.0;
+      if (p <= 1.08) {
+        decay0_nucltransK(prng_, event_, 0.1889, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_799;
+      }
+      p  = 100. * prng_();
+      if (p <= 3.85) {
+        decay0_nucltransK(prng_, event_, 0.6312, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 0.9881, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_867:
+      thlev = 0.0;
+      decay0_nucltransK(prng_, event_, 0.5101, 0.01347, 0.00165, 0.0, tclev, thlev, tdlev);
+      goto label_357;
+
+    label_799:
+      thlev = 0.0;
+      if (p <= 4.91) {
+        decay0_nucltransK(prng_, event_, 0.4424, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+        goto label_357;
+      }
+      decay0_nucltransK(prng_, event_, 0.7991, 0.01347, 0.0, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_357:
+      thlev = 0.0;
+      decay0_nucltransK(prng_, event_, 0.3567, 0.01347, 0.00382, 0.0, tclev, thlev, tdlev);
+      goto label_10000;
+
+    label_10000:
+      return;
+  
+}
+  // end of Se83.f
+
+} // end of namespace bxdecay0
+
+// end of Se83.cc
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/Se83.h b/bxdecay0/Se83.h
new file mode 100644
index 0000000..4f3ef82
--- /dev/null
+++ b/bxdecay0/Se83.h
@@ -0,0 +1,17 @@
+#ifndef BXDECAY0_SE83_H
+#define BXDECAY0_SE83_H
+
+namespace bxdecay0 {
+
+  class i_random;
+  class event;
+
+  void Se83(i_random & prng_, event & event_, const double tcnuc_, double & tdnuc_);
+
+} // end of namespace bxdecay0
+
+#endif // BXDECAY0_SE83_H
+
+// Local Variables: --
+// mode: c++ --
+// End: --
diff --git a/bxdecay0/genbbsub.cc b/bxdecay0/genbbsub.cc
index 24f1dab..75b1c41 100644
--- a/bxdecay0/genbbsub.cc
+++ b/bxdecay0/genbbsub.cc
@@ -113,9 +113,11 @@
 #include <bxdecay0/Sb125.h>
 #include <bxdecay0/Sb126.h>
 #include <bxdecay0/Sb133.h>
-// #include <bxdecay0/Sc44.h> // Added 2025-12-XX
+#include <bxdecay0/Sc44.h> // Added Sc44 and Sc44m on 2025-12-16
+#include <bxdecay0/Sc44m.h>
 #include <bxdecay0/Sc48.h>
 #include <bxdecay0/Se76low.h>
+#include <bxdecay0/Se83.h> // Added 2025-12-16
 #include <bxdecay0/Sm148low.h>
 #include <bxdecay0/Sm150low.h>
 #include <bxdecay0/Sn114low.h>
@@ -2148,7 +2150,9 @@ namespace bxdecay0 {
         } else if (name_starts_with(chnuclide_, "Sb125")) {
         } else if (name_starts_with(chnuclide_, "Sb126")) {
         } else if (name_starts_with(chnuclide_, "Sb133")) {
-        // } else if (name_starts_with(chnuclide_, "Sc44")) { // Added 2025-12-1XX
+        } else if (name_starts_with(chnuclide_, "Sc44")) { // Added Sc44 and Sc44m on 2025-12-16
+        } else if (name_starts_with(chnuclide_, "Sc44m")) { 
+        } else if (name_starts_with(chnuclide_, "Se83")) { // Added 2025-12-16
         } else if (name_starts_with(chnuclide_, "Sr90")) {
         } else if (name_starts_with(chnuclide_, "Ta180m")) { // 'Ta180m-B-' and 'Ta180m-EC' 
         } else if (name_starts_with(chnuclide_, "Ta182")) {
@@ -2573,9 +2577,15 @@ namespace bxdecay0 {
       if (name_starts_with(chnuclide_, "Sb133")) {
         Sb133(prng_, event_, 0., tdnuc);
       }
-      // if (name_starts_with(chnuclide_, "Sc44")) {
-      //   Sc44(prng_, event_, 0., tdnuc); // Added 2025-12-XX
-      // }
+      if (name_starts_with(chnuclide_, "Sc44")) {
+        Sc44(prng_, event_, 0., tdnuc); // Added 2025-12-16
+      }
+      if (name_starts_with(chnuclide_, "Sc44m")) {
+        Sc44m(prng_, event_, 0., tdnuc); // Added 2025-12-16
+      }
+      if (name_starts_with(chnuclide_, "Se83")) { // Added 2025-12-16
+        Se83(prng_, event_, 0., tdnuc);
+      }
       if (name_starts_with(chnuclide_, "Sr90")) {
         Sr90(prng_, event_, 0., tdnuc);
       }
diff --git a/bxdecay0/testing/test_Sc44.cxx b/bxdecay0/testing/test_Sc44.cxx
new file mode 100644
index 0000000..8507a8b
--- /dev/null
+++ b/bxdecay0/testing/test_Sc44.cxx
@@ -0,0 +1,62 @@
+/** test_Sc44.cxx
+ *
+ * This file is part of BxDecay0.
+ *
+ * BxDecay0 is free software: you  can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free  Software Foundation, either  version 3 of the  License, or
+ * (at your option) any later version.
+ *
+ * BxDecay0 is distributed  in the hope that it will  be useful, but
+ * WITHOUT  ANY   WARRANTY;  without  even  the   implied  warranty  of
+ * MERCHANTABILITY or  FITNESS FOR A  PARTICULAR PURPOSE.  See  the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with BxDecay0.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// Standard library:
+#include <chrono>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <limits>
+#include <random>
+
+// This project:
+#include <bxdecay0/bb.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/genbbsub.h>
+#include <bxdecay0/std_random.h>
+#include <bxdecay0/Sc44.h>
+
+int main()
+{
+  int error_code = EXIT_SUCCESS;
+  try {
+
+    unsigned int seed = 314159;
+    std::default_random_engine generator(seed);
+    bxdecay0::std_random prng(generator);
+
+    bxdecay0::event decay;
+    double t_creation = 0.0;
+    double t_decay    = 0.0;
+    bxdecay0::Sc44(prng, decay, t_creation, t_decay);
+
+    decay.set_time(t_decay);
+    decay.print(std::clog, "Sc-44 event:", "[info] ");
+    decay.store(std::cout);
+
+  } catch (std::exception & error) {
+    std::cerr << "[error] " << error.what() << std::endl;
+    error_code = EXIT_FAILURE;
+  } catch (...) {
+    std::cerr << "[error] "
+              << "Unexpected exception!" << std::endl;
+    error_code = EXIT_FAILURE;
+  }
+  return error_code;
+}
\ No newline at end of file
diff --git a/bxdecay0/testing/test_Sc44m.cxx b/bxdecay0/testing/test_Sc44m.cxx
new file mode 100644
index 0000000..657b183
--- /dev/null
+++ b/bxdecay0/testing/test_Sc44m.cxx
@@ -0,0 +1,62 @@
+/** test_Sc44m.cxx
+ *
+ * This file is part of BxDecay0.
+ *
+ * BxDecay0 is free software: you  can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free  Software Foundation, either  version 3 of the  License, or
+ * (at your option) any later version.
+ *
+ * BxDecay0 is distributed  in the hope that it will  be useful, but
+ * WITHOUT  ANY   WARRANTY;  without  even  the   implied  warranty  of
+ * MERCHANTABILITY or  FITNESS FOR A  PARTICULAR PURPOSE.  See  the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with BxDecay0.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// Standard library:
+#include <chrono>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <limits>
+#include <random>
+
+// This project:
+#include <bxdecay0/bb.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/genbbsub.h>
+#include <bxdecay0/std_random.h>
+#include <bxdecay0/Sc44m.h>
+
+int main()
+{
+  int error_code = EXIT_SUCCESS;
+  try {
+
+    unsigned int seed = 314159;
+    std::default_random_engine generator(seed);
+    bxdecay0::std_random prng(generator);
+
+    bxdecay0::event decay;
+    double t_creation = 0.0;
+    double t_decay    = 0.0;
+    bxdecay0::Sc44m(prng, decay, t_creation, t_decay);
+
+    decay.set_time(t_decay);
+    decay.print(std::clog, "Sc-44m event:", "[info] ");
+    decay.store(std::cout);
+
+  } catch (std::exception & error) {
+    std::cerr << "[error] " << error.what() << std::endl;
+    error_code = EXIT_FAILURE;
+  } catch (...) {
+    std::cerr << "[error] "
+              << "Unexpected exception!" << std::endl;
+    error_code = EXIT_FAILURE;
+  }
+  return error_code;
+}
\ No newline at end of file
diff --git a/bxdecay0/testing/test_Se83.cxx b/bxdecay0/testing/test_Se83.cxx
new file mode 100644
index 0000000..7129e6a
--- /dev/null
+++ b/bxdecay0/testing/test_Se83.cxx
@@ -0,0 +1,62 @@
+/** test_Se83.cxx
+ *
+ * This file is part of BxDecay0.
+ *
+ * BxDecay0 is free software: you  can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free  Software Foundation, either  version 3 of the  License, or
+ * (at your option) any later version.
+ *
+ * BxDecay0 is distributed  in the hope that it will  be useful, but
+ * WITHOUT  ANY   WARRANTY;  without  even  the   implied  warranty  of
+ * MERCHANTABILITY or  FITNESS FOR A  PARTICULAR PURPOSE.  See  the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with BxDecay0.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// Standard library:
+#include <chrono>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <limits>
+#include <random>
+
+// This project:
+#include <bxdecay0/bb.h>
+#include <bxdecay0/event.h>
+#include <bxdecay0/genbbsub.h>
+#include <bxdecay0/std_random.h>
+#include <bxdecay0/Se83.h>
+
+int main()
+{
+  int error_code = EXIT_SUCCESS;
+  try {
+
+    unsigned int seed = 314159;
+    std::default_random_engine generator(seed);
+    bxdecay0::std_random prng(generator);
+
+    bxdecay0::event decay;
+    double t_creation = 0.0;
+    double t_decay    = 0.0;
+    bxdecay0::Se83(prng, decay, t_creation, t_decay);
+
+    decay.set_time(t_decay);
+    decay.print(std::clog, "Se-83 event:", "[info] ");
+    decay.store(std::cout);
+
+  } catch (std::exception & error) {
+    std::cerr << "[error] " << error.what() << std::endl;
+    error_code = EXIT_FAILURE;
+  } catch (...) {
+    std::cerr << "[error] "
+              << "Unexpected exception!" << std::endl;
+    error_code = EXIT_FAILURE;
+  }
+  return error_code;
+}
\ No newline at end of file
diff --git a/resources/description/background_isotopes.lis b/resources/description/background_isotopes.lis
index 0f74e54..cfe701e 100644
--- a/resources/description/background_isotopes.lis
+++ b/resources/description/background_isotopes.lis
@@ -44,9 +44,12 @@ Ra228
 Rb87
 Rh106
 Rn222
+Sc44
+Sc44m
 Sb125
 Sb126
 Sb133
+Se83
 Sr90
 Ta180m-B-
 Ta180m-EC