Transcript Francesco Recchia

PRESORT OF THE DATA OF THE
COLOGNE TEST EXPERIMENT
Quality and integrity of data
● Detector numbering and positions
● Calibrations and gain stability
● Reactions channels identification
●
The experiment
Main characteristics of the setup
BEAM
48Ti
TARGET
48Ti
100 MeV
+ 2H
thickness
Si detector segmentatio
220 μg/cm2
300 μm
32 rings, 64 sectors
n
Absorber
thickness
16 μm (Al)
AGATA symmetric triple-cluster
What to check
●
Quality and integrity of data
–
Sector energies mostly missing
–
Some segments are in short circuit and other are
missing
●
Detector numbering and positions
●
Calibrations and gain stability
●
Reactions channels as expected ?
Quality and integrity of data
• Silicon detector fires with almost all his
sectors and rings every event
• The time of a lot of channels is in overflow
TDC of silicon detector
We can ask for a validation
with an autocoincidence
After validation the
multiplicity of sectors and
rings is (1, 1) as expected
for the reaction
validation
Quality and integrity of data
TDC of germanium detector
real gate
TDC of silicon detector
validation
Quality and integrity of data
With gate on sector energy
Without gate on sector energy
Quality and integrity of data
Some segments
missing/low statistics
2 segments in
short circuit
3 segments in
short circuit
What to check
●
Quality and integrity of data
●
Detector numbering and positions
–
Ring numbering
–
Sector numbering
–
Silicon detector position
●
Calibrations and gain stability
●
Reactions channels as expected?
Geometry – ring numbering
Counts on the rings ~ ring solid angle
Tape number 19: alpha source
●
Inverse numbering of
the rings
●
The distance between
the source and the
silicon detector is 34
mm
(what about the target?)
Geometry – sector numbering
49Ti:
1381 keV
48Ti:
983 keV
Ecm 1   2
Elab 
1   cos( )
Depends on the
angle of the
firing sector
The Doppler correction depends also on:
• the mass of the scatterer nucleus
• the reaction mechanism
Geometry – sector numbering
Eγ – sector #
Eγ – sector #
x
0
8
63
56
12.3 ± 0.5 deg
16
y
Ge detectors
48
24
FRONT view
(from the target)
40
32
Center of the cluster
in the yz plane
Geometry – silicon detector
position
ring # – sector #
ring # – sector #
SI DETECTOR IS NOT
PERPENDICULAR TO BEAM
ANGLE (θ): 4.50 ± 0.02 deg
DIRECTION (φ): 100.4 ± 0.1 deg
(~ direction of sector 19)
θ = 4.5 deg
Si det
BEAM IS OFF AXIS
DISTANCE: 2.67 ± 0.01 mm
DIRECTION: 100.4 ± 0.1 deg
(~ direction of sector 19)
OR
d = 2.7 mm
Rint = 16.5 mm
Target
beam
Center of silicon
detector
Beam position
What to check
●
Quality and integrity of data
●
Detector numbering and positions
●
Calibrations and gain stability
–
●
DGF stability
Reactions channels as expected?
Electronics stability
DGF gain stability:
●
rough calibration using
60Co
●
sources
fine recalibration using
511 keV peak during run
with beam
What to check
●
Quality and integrity of data
●
Calibrations and gain stability
●
Detector numbering and positions
●
Reactions channels as expected?
–
(d,p) 49Ti
–
(d,d’) and (d,pn) 48Ti
–
Other reaction channels ?
Channel identification:
gamma spectrum
Gammas from 49Ti
keV
Channel identification:
(d,p) through direct reaction
Q value of (d,p)
reaction: 5.92 MeV
Excitation energy: 6.2 MeV
Channel identification:
(d,p) through fusion evaporation
PACE calculation:
proton spectrum in CM
keV
Proton with 4.5 MeV in CM
4.5
3.5
PACE Coulomb barrier: 3.95 MeV
6.5
5.5
Channel identification:
gamma spectrum
Gammas from 49Ti and 48Ti
Channel identification:
(d,d') direct and (d, pn) fusion
evaporation
Gate on gamma
energy 983 keV
(d,d’) direct
(d,pn) fusion-evaporation (?)
Channel identification:
other reaction channels ?
Gate on gamma
energy 983 keV
Protons and deuterons
can not deposit so
much energy
Is it noise?
Why only at
small angles?
Channel identification:
other reaction channels ?
48Ti
2H
Channel identification:
other reaction channels ?
12C
16O
Channel identification:
other reaction channels ?
Absorber thickness:
16 µm
12C
14N
16O
logbook
ABSORBER
NUCLEUS
6 µm
48Ti
10 µm
27Al
16 µm
16O
18 µm
14N
21 µm
12C
Channel identification:
other reaction channels ?
Channel identification:
other reaction channels ?
Channel identification:
other reaction channels ?
Low energy
?
High energy
changed Si-HV and
threshold
• Time correlation between high and low energy events in
si-detector
• Concentration of impurities increases with time
• High concentration of low energy events in tape 15 and 16
not understood
new target
(chamber opened)
Channel identification:
other reaction channels ?
Overflow is expected
here but there is not!
Channel identification:
other reaction channels ?
Overflow is expected
here but there is not!
This region has the right:
• deflection angles
• gamma spectrum
• statistical dependence on
time
• Doppler correction
Channel identification:
other reaction channels ?
Overflow is expected
here but there is not!
This region has the right:
• deflection angles
• gamma spectrum
• statistical dependence on
time
• Doppler correction
This can mean that electronics did
not work the way we expected
Channel identification:
other coulex reactions
This region has the right:
• deflection angles
• gamma spectrum
• statistical dependence on
time
• Doppler correction
This can mean that electronics did
not work the way we expected
Channel identification:
statistics and selection
mechanis
Gamma
Energy in
m
energy
silicon
counts
detector
direct
mixed
1381
(d,p)
keV
750k
(d,p)
fus-evap
1381
keV
(d,d’)
direct
983 keV
< 30k
(d,pn)
fus-evap
983 keV
< 15k
mixed
220k counts
(HI, HI’)
coulex
983 keV
E > 8 MeV
80k
Conclusion: what to analyse ?
Beam was 48Ti
No direct reaction
on target
Experiment designed
for d(47Ti, 48Ti)p
direct reaction
12C
We still have a nice direct reaction
on contaminant(s) !
BUT
16O
• Smaller statistics
• Use of background
Quality and integrity of data
Quality and integrity of data
Data structure
Silicon
detector
Germanium
detector
Sector #, Energy, Time
Sector #, Energy, Time
…
Ring #, Energy, Time
Ring #, Energy, Time
…
VME modules
Germanium #, Energy, Time
…
Segment #, Trace, Energy
….
DGF modules