diff --git a/BloubWorld/bloubspace.f90 b/BloubWorld/bloubspace.f90
index cab17c7..62979d4 100644
--- a/BloubWorld/bloubspace.f90
+++ b/BloubWorld/bloubspace.f90
@@ -28,9 +28,9 @@ module bloubspace
     blb%py = rand() * 0.25
     blb%pz = rand() - 0.50
 
-    blb%vx = (rand() - 0.5) / 5.000
-    blb%vy = (rand() - 0.5) / 5.000
-    blb%vz = (rand() - 0.5) / 5.000
+    blb%vx = (rand() - 0.5) / 4.000
+    blb%vy = (rand() - 0.5) / 4.000
+    blb%vz = (rand() - 0.5) / 4.000
 
   end subroutine
 
@@ -39,7 +39,9 @@ module bloubspace
   subroutine move_bloub (blb, coef)
     type(t_bloubs), intent (inout)  :: blb
     real,           intent (in)     :: coef
-    
+
+    ! we must check that this bloub is alive ?
+
     blb%px  = blb%px + (blb%vx * coef)
     blb%py  = blb%py + (blb%vy * coef)
     blb%pz  = blb%pz + (blb%vz * coef)
diff --git a/BloubWorld/genbloubs.f90 b/BloubWorld/genbloubs.f90
index 3e79961..71b9989 100644
--- a/BloubWorld/genbloubs.f90
+++ b/BloubWorld/genbloubs.f90
@@ -31,7 +31,7 @@ program genbloubs
     bloub%nick = 'noname  '
     bloub%alive = .TRUE.
     call random_pv(bloub)
-    bloub%radius = 0.009999
+    bloub%radius = 0.025
     bloub%seq    = 0
 
     write(idu) bloub              ! no error control ?
diff --git a/BloubWorld/movebloubs.f90 b/BloubWorld/movebloubs.f90
index 2015647..47d18ba 100644
--- a/BloubWorld/movebloubs.f90
+++ b/BloubWorld/movebloubs.f90
@@ -44,7 +44,7 @@ program movebloubs
       exit
     endif
 
-    call move_bloub (bloub, 0.333)
+    call move_bloub (bloub, 1.10)
 
     bx = bx + bloub%px
     by = by + bloub%py
@@ -55,6 +55,10 @@ program movebloubs
       bloub%vy = -1.0 * bloub%vy
       bloub%py = 0.0
     endif
+    if (3.0 .lt. bloub%py) then
+      bloub%vy = -1.0 * bloub%vy
+      bloub%py = 3.0
+    endif
 
     write(outu) bloub     ! no error control ?