diff --git a/src/modules/moduleSolver.f90 b/src/modules/moduleSolver.f90
index be78420..d0b2d01 100644
--- a/src/modules/moduleSolver.f90
+++ b/src/modules/moduleSolver.f90
@@ -660,24 +660,18 @@ MODULE moduleSolver
       TYPE(particle), INTENT(inout):: part
       CLASS(meshVol), POINTER, INTENT(in):: volOld
       CLASS(meshVol), POINTER, INTENT(inout):: volNew
-      REAL(8):: fractionVolume, fractionWeight
-      INTEGER:: nSplit
+      REAL(8):: fractionVolume, pSplit
 
-      !If particle has change cell, call Weighting scheme
-      IF (volOld%n /= volNew%n) THEN
+      !If particle changes volume to smaller cell
+      IF (volOld%volume > volNew%volume) THEN
         fractionVolume = volOld%volume/volNew%volume
 
-        part%weight = part%weight * fractionVolume
+        !Calculate probability of splitting particle
+        pSplit = 1.D0 - DEXP(-fractionVolume)
 
-        fractionWeight = part%weight / part%species%weight
-
-        IF (fractionWeight >= 2.D0) THEN
-          nSplit = FLOOR(fractionWeight)
-          CALL splitParticle(part, nSplit, volNew)
-
-        ELSEIF (part%weight < 1.D0) THEN
-          !Particle has lost statistical meaning and will be terminated
-          part%n_in = .FALSE.
+        IF (random() < pSplit THEN
+          !Split particle in two
+          CALL splitParticle(part, 2, volNew)
 
         END IF