PRESORT OF THE DATA OF THE COLOGNE TEST EXPERIMENT ● Quality and integrity of data ● Detector...

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 100 MeV

TARGET 48Ti + 2H 220 μg/cm2

Si detector

thickness 300 μm

segmentation 32 rings, 64 sectors

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

validation

• Silicon detector fires with almost all his sectors and rings every event

• The time of a lot of channels is in overflow

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

TDC of silicon detector


real gate validation

TDC of silicon detectorTDC of germanium detector


With gate on sector energy

Without gate on sector energy


3 segments in short circuit

2 segments in short circuit

Some segments missing/low statistics

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

)cos(1

1 2

cmlab

EE

Depends on the angle of the firing sector

49Ti: 1381 keV

48Ti: 983 keV

The Doppler correction depends also on:

• the mass of the scatterer nucleus

• the reaction mechanism

Geometry – sector numbering

x

y

12.3 ± 0.5 deg

08

16

24

3240

48

56

63

FRONT view (from the target)

Center of the cluster in the yz plane

Ge detectors

Eγ – sector # Eγ – sector #

Geometry – silicon detector position

BEAM IS OFF AXISDISTANCE: 2.67 ± 0.01 mmDIRECTION: 100.4 ± 0.1 deg (~ direction of sector 19)

Center of silicon detector

Beam position

SI DETECTOR IS NOT PERPENDICULAR TO BEAMANGLE (θ): 4.50 ± 0.02 degDIRECTION (φ): 100.4 ± 0.1 deg (~ direction of sector 19)

OR

beam

Si det

Target

Rint = 16.5 mmd = 2.7 mmθ = 4.5 deg

ring # – sector # ring # – sector #

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

Channel identification: (d,p) through direct reaction

Q value of (d,p) reaction: 5.92 MeV

Excitation energy: 6.2 MeV

keV

keV

Channel identification: (d,p) through fusion evaporation

PACE calculation: proton spectrum in CM

PACE Coulomb barrier: 3.95 MeV

Proton with 4.5 MeV in CM

4.53.5

5.56.5

Channel identification: gamma spectrum

Gammas from 49Ti and 48Ti

Channel identification: (d,d') direct and (d, pn) fusion

evaporation

(d,d’) direct (d,pn) fusion-evaporation (?)

Gate on gamma energy 983 keV

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?

48Ti

2H


16O

12C


12C 14N 16O


Absorber thickness: 16 µm

ABSORBER NUCLEUS

6 µm 48Ti

10 µm 27Al

16 µm 16O

18 µm 14N

21 µm 12C

logbook

Low energy

High energy?

• 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)

changed Si-HV and threshold

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 can mean that electronics did not work the way we expected

Channel identification: statistics and selection

mechanism Gamma energy

Energy in silicon detector

counts

(d,p) direct 1381 keV

750k(d,p) fus-evap 1381 keV

(d,d’) direct 983 keV < 30k

(d,pn) fus-evap 983 keV < 15k

(HI, HI’) coulex 983 keV E > 8 MeV 80k

(HI, HI’) coulex 983 keV 2 < E < 8 MeV ~ 100k

(HI, HI’) coulex 983 keV 0.3 < E < 2 MeV 140k

mixed

mixed

220k counts

Conclusion: what to analyse ?

16O

12C

Experiment designed for d(47Ti, 48Ti)p direct

reaction

Beam was 48Ti No direct reaction

on target

We still have a nice direct reaction on contaminant(s) !

BUT

• Smaller statistics• Use of background

Quality and integrity of dataData structure

Sector #, Energy, Time Sector #, Energy, Time…Ring #, Energy, Time Ring #, Energy, Time…

Germanium #, Energy, Time…

Segment #, Trace, Energy….

Silicon detector

Germanium detector

VME modules

DGF modules

PRESORT OF THE DATA OF THE COLOGNE TEST EXPERIMENT ● Quality and integrity of data ● Detector...

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