Difference in "statistics" for same run of DOSE and DOSE-EQ

Dear FLUKA experts

I try to simulate a proton field impinging a cubic water phantom. I am
interested in scoring neutron dose and neutron dose equivalent.
Therefore I use USRBIN estimators in combination with AUXSCORE card to
filter the dose for particle NEUTRON and in case of dose equivalent for
ambient dose equivalent using SDUM AMB74.

I attached for both cases a depth dose curve along the beam direction.
My question is now, why does one curve (dose equivalent) look more or
less smooth and the one of absorbed dose does not? The data is taken
from the same run, so both estimators should score the same number of
neutrons shouldn't they?

The FLUKA input file is also attached.

Thanks for your help!

Cheers
Roger

    0 0 Rectangular phantom (30x30x30 cm^3) at SSD30
*
* Bodies
* ------
*
* General definitions:
* blackhole to include geometry
SPH BLK 0.0 0.0 0.0 10000.0
* void
RPP VAC -1000.0 1000.0 -1000.0 1000.0 -1000.0 1000.0
* Treatment room air
RPP ROOM -100.0 100.0 -100.0 100.0 -100.0 30.0
* Body for phantom
RPP PHANTOM -15.0 15.0 -15.0 15.0 -30.0 0.0
XYP WATERP01 -1.0
XYP WATERP02 -2.0
XYP WATERP03 -3.0
XYP WATERP04 -4.0
XYP WATERP05 -5.0
XYP WATERP06 -6.0
XYP WATERP07 -7.0
XYP WATERP08 -8.0
XYP WATERP09 -9.0
XYP WATERP10 -10.0
XYP WATERP11 -11.0
XYP WATERP12 -12.0
XYP WATERP13 -13.0
XYP WATERP14 -14.0
XYP WATERP15 -15.0
XYP WATERP16 -16.0
XYP WATERP17 -17.0
XYP WATERP18 -18.0
XYP WATERP19 -19.0
XYP WATERP20 -20.0
XYP WATERP21 -21.0
XYP WATERP22 -22.0
XYP WATERP23 -23.0
XYP WATERP24 -24.0
XYP WATERP25 -25.0
XYP WATERP26 -26.0
XYP WATERP27 -27.0
XYP WATERP28 -28.0
XYP WATERP29 -29.0
END
*
* Regions
* -------
*
* Blackhole
BLKHOLE 5 +BLK -VAC
* Vacuum outside treatment room
VACUUM 5 +VAC -ROOM
* Air around target
AIR 5 +ROOM -PHANTOM
* Water phantom
WPHAN01 5 +PHANTOM -WATERP01
WPHAN02 5 +PHANTOM +WATERP01 -WATERP02
WPHAN03 5 +PHANTOM +WATERP02 -WATERP03
WPHAN04 5 +PHANTOM +WATERP03 -WATERP04
WPHAN05 5 +PHANTOM +WATERP04 -WATERP05
WPHAN06 5 +PHANTOM +WATERP05 -WATERP06
WPHAN07 5 +PHANTOM +WATERP06 -WATERP07
WPHAN08 5 +PHANTOM +WATERP07 -WATERP08
WPHAN09 5 +PHANTOM +WATERP08 -WATERP09
WPHAN10 5 +PHANTOM +WATERP09 -WATERP10
WPHAN11 5 +PHANTOM +WATERP10 -WATERP11
WPHAN12 5 +PHANTOM +WATERP11 -WATERP12
WPHAN13 5 +PHANTOM +WATERP12 -WATERP13
WPHAN14 5 +PHANTOM +WATERP13 -WATERP14
WPHAN15 5 +PHANTOM +WATERP14 -WATERP15
WPHAN16 5 +PHANTOM +WATERP15 -WATERP16
WPHAN17 5 +PHANTOM +WATERP16 -WATERP17
WPHAN18 5 +PHANTOM +WATERP17 -WATERP18
WPHAN19 5 +PHANTOM +WATERP18 -WATERP19
WPHAN20 5 +PHANTOM +WATERP19 -WATERP20
WPHAN21 5 +PHANTOM +WATERP20 -WATERP21
WPHAN22 5 +PHANTOM +WATERP21 -WATERP22
WPHAN23 5 +PHANTOM +WATERP22 -WATERP23
WPHAN24 5 +PHANTOM +WATERP23 -WATERP24
WPHAN25 5 +PHANTOM +WATERP24 -WATERP25
WPHAN26 5 +PHANTOM +WATERP25 -WATERP26
WPHAN27 5 +PHANTOM +WATERP26 -WATERP27
WPHAN28 5 +PHANTOM +WATERP27 -WATERP28
WPHAN29 5 +PHANTOM +WATERP28 -WATERP29
WPHAN30 5 +PHANTOM +WATERP29
END

# FLUKA Project file
Version: 1
Title: 10x10 cm^2 proton beam of 160 MeV impinging an water phantom
Input: protons_160MeV_water.inp
Debug: "Region #1" 25.0 -1.0 -25.0 30.0 1.0 30.0 100 100 1000
DefMain: True
LinkPrg: lfluka
F77bound: True
F77dline: False
FlukaVar: FLUPRO

# Run information
Run: <default>
Prev: 0
Last: 10
Status: 3
Pid: 0
StartRun: 1278593843

# USRxxx data file: neutron_water_p160MeV_eq-dose_neutron
Data: neutron_water_p160MeV_eq-dose_neutron
Unit: 30
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
Rule: +,\I_parallel\d\d\d\d_fort\.\U
EndData

# USRxxx data file: neutron_water_p160MeV_dose_neutron
Data: neutron_water_p160MeV_dose_neutron
Unit: 34
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
Rule: +,\I_parallel\d\d\d\d_fort\.\U
EndData
EndRun

# Run information
Run: protons_160MeV_water_parallel1
Rnd: 893567821
Prev: 0
Last: 10
Status: 3
Pid: 0
StartRun: 1278593867

# USRxxx data file: protons_160MeV_water_parallel1_usrbin_30
Data: \I_\T_\U
Unit: 30
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData

# USRxxx data file: protons_160MeV_water_parallel1_usrbin_34
Data: \I_\T_\U
Unit: 34
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData
EndRun

# Run information
Run: protons_160MeV_water_parallel2
Rnd: 65389253
Prev: 0
Last: 10
Status: 3
Pid: 0
StartRun: 1278593883

# USRxxx data file: protons_160MeV_water_parallel2_usrbin_30
Data: \I_\T_\U
Unit: 30
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData

# USRxxx data file: protons_160MeV_water_parallel2_usrbin_34
Data: \I_\T_\U
Unit: 34
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData
EndRun

# Run information
Run: protons_160MeV_water_parallel3
Rnd: 183652835
Prev: 0
Last: 10
Status: 3
Pid: 0
StartRun: 1278594874

# USRxxx data file: protons_160MeV_water_parallel3_usrbin_30
Data: \I_\T_\U
Unit: 30
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData

# USRxxx data file: protons_160MeV_water_parallel3_usrbin_34
Data: \I_\T_\U
Unit: 34
Type: b
Recursive: 0
Rule: +,\I\d\d\d_fort\.\U
Rule: +,\I\d\d\d_ftn\.\U
EndData
EndRun

# Geometry plot "Geometry Proton beam of 160 MeV impinging a water phantom"
Plot: neutron_water_geometry
Title: Geometry Proton beam of 160 MeV impinging a water phantom
Format:
Type: Geometry
LineType:
Keys: 1
origin: 0 0 0
showcenter: 0
vectscale: 0.1
labels: 1
coord: X-Y
boundaries: 0
subtype: Geometry
extends: 100 100
basisu: 1 0 0
basisv: 0 1 0
AutoAspect: 1
nu: 200
nv: 200
EndPlot

# USRBIN plot "Neutron equivalent dose water protons 160 MeV"
Plot: neutron_water_p160MeV_eq-dose_neutron_plot
Title: Neutron equivalent dose water protons 160 MeV
Format: .eps
Type: USRBIN
LineType:
Keys: 1
Ratio: 1.0
XLabel: z / cm
YLabel: Neutron ambient dose equivalent / pSv per primary
CBLabel: Neutron ambient dose equivalent / pSv per primary
cbround: 1
cbcpd: 3
int: 867.219482
lt.0: 1
lw.0: 1
ls.0: 0
cbcolors: 30
errors: 0
log: 0
min: 0.00742100552
xrebin: 1
axes: Auto
hist: 1D Projection
proj: Z
swap: 0
with.0: steps
zrebin: 1
max: 0.0475798808
yrebin: 1
geo: -Auto-
axes.0: x1y1
ps.0: 1
datafile: neutron_water_p160MeV_eq-dose_neutron
det: 1
cbpalette: FLUKA
pt.0: 1
EndPlot

# USRBIN plot "Neutron absorbed dose water protons 160 MeV"
Plot: neutron_water_p160MeV_dose_neutron_plot
Title: Neutron absorbed dose water protons 160 MeV
Format: .eps
Type: USRBIN
LineType:
Keys: 1
Ratio: 1.0
XLabel: z / cm
YLabel: Neutron dose / GeV/g per primary
CBLabel: Neutron dose / GeV/g per primary
cbround: 1
cbcpd: 3
int: 8.58868173E-05
lt.0: 1
lw.0: 1
ls.0: 0
cbcolors: 30
errors: 0
log: 0
min: 5.5603222E-10
xrebin: 1
axes: Auto
hist: 1D Projection
proj: Z
swap: 0
with.0: steps
zrebin: 1
max: 5.46572076E-09
yrebin: 1
geo: -Auto-
axes.0: x1y1
ps.0: 1
datafile: neutron_water_p160MeV_dose_neutron
det: 1
cbpalette: FLUKA
pt.0: 1
EndPlot

* ..+....1....+....2....+....3....+....4....+....5....+....6....+....7...
TITLE
10x10 cm^2 proton beam of 160 MeV impinging a water phantom
*
* use names everywhere and free format for geometry
DEFAULTS
PRECISIO
RANDOMIZ 1. 0.0
START 10000.0
*
* beam definitions
BEAM -0.16 0.0 0.0 10.0 10.0 1.0PROTON
BEAMPOS 0.0 0.0 30.1 0.0 0.0
NEGATIVE
EMFRAY 4. BLKHOLE @LASTREG 1.0
DELTARAY 0.00001 100.0 1.03 AIR NOPRINT
DELTARAY 0.00001 100.0 1.03 WATER NOPRINT
GEOBEGIN 21.
COMBNAME
neutron_solid_phantom.geo
GEOEND
MATERIAL 1.0 WATER
COMPOUND 2.0 HYDROGEN 1.0 OXYGEN WATER
MATERIAL 0.1956 CO2
COMPOUND 1.0 CARBON 2.0 OXYGEN CO2
MATERIAL 0.001204 AIR
COMPOUND -.75518 NITROGEN -0.23135 OXYGEN -.01288 ARGONAIR
COMPOUND -0.00058 CO2 AIR
* Material assignments
ASSIGNMA BLCKHOLE BLKHOLE
ASSIGNMA VACUUM VACUUM
ASSIGNMA WATER WPHAN01 WPHAN30 1.0
ASSIGNMA AIR AIR
EMFFIX AIR 0.1 WATER 0.05
EMFCUT -1.0E-06 1.0E-06 0.0 AIR
PROD-CUT
EMFCUT -1.0E-06 1.0E-06 0.0 WATER
PROD-CUT
* Scoring
*
* Dose
USRBIN 10. DOSE-EQ -30. 15.0 15.0
0.0NDOSPHAN
USRBIN -15.0 -15.0 -30.0 150.0 150.0 150.0&
AUXSCORE USRBIN NEUTRON NDOSPHAN NDOSPHAN AMB74
USRBIN 10. DOSE -34. 15.0 15.0
0.0NEDOPHAN
USRBIN -15.0 -15.0 -30.0 150.0 150.0 150.0&
AUXSCORE USRBIN NEUTRON NEDOPHAN NEDOPHAN
STOP