22 ne@131 mev + 208 pb: a prisma+clara data analysis
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2222Ne@131 MeV + Ne@131 MeV + 208208Pb:Pb:
a PRISMA+CLARA data a PRISMA+CLARA data
analysisanalysis
Paolo Mason
Part 1Part 1
From raw data to mass From raw data to mass spectraspectra
PRISMA+CLARA: the set-upPRISMA+CLARA: the set-up
Target
Rotating platform
Focal plane [PPAC]
Quadrupole
Start detector [MCP]
Dipole
Ionization chamber [IC]
- Time of flight → directly involved in calculation of speed, therefore of
- mass [mv2/R=qBv → m=qB•R/v]
- Q-value
- γ-ray energies (Doppler correction)
- Entrance and focal-plane space coordinates → used to reconstruct
- total distance D covered inside PRISMA (v = D/TOF)
- trajectory’s curvature radius R in dipole magnet
- Energy released in IC (each section) → used to select events (Z and q)
- γ-rays → (even when not of intrinsic interest, anyway) VERY useful to
- check Z, A attributions
- “calibrate” the TOF (Doppler correction)
- understand Q-value spectra.
PRISMA+CLARA: measured quantities PRISMA+CLARA: measured quantities
Three signals of interest:
- entrance X coordinate
- entrance Y coordinate
- TOF start
Actions:
- noise removal
- “calibration” of X,Y signals
The MCP (entrance) detectorThe MCP (entrance) detector
MCP X [arb. units]
MC
P Y
[a.u
.]
coincidence with some focal-plane signal
MCP X [arb. units]
MC
P Y
[a.u
.]
Enhancing the focal-plane efficiencyEnhancing the focal-plane efficiencywith the cathode signal 1/2with the cathode signal 1/2
Scathode/left/right = cathode/left/right signal
Light ions produce weak signals which may be cut by CFD thresholds
→ Need to use the cathode signal when the left or right signal is not there
Removing cathode noise
Scathode [arb. units]
(Sle
ft+
Sri
ght)/2
[a.u
.] Sec. #33000
987
Establishing link between values of Xfp determined with/without Scathode
1083 3141(Scathode-Sleft)/2 [a.u.]
(Sri
ght-S
left)/
4 [a
.u.] Sec. #3
Enhancing the focal-plane efficiencyEnhancing the focal-plane efficiencywith the cathode signal 2/2with the cathode signal 2/2
R/v
[arb
. u
nit
s]
0focal-plane X [mm]
1023
With cathode signal
R/v
[arb
. u
nit
s]
0focal-plane X [mm]
1023
Without cathode signal
PPAC section
1 2 3 4 5 6 7 8 9
Efficiency enhancement 1.6 2.1 2.5 2.2 1.6 1.7 5.7 1.5 1.4
Coarse matching of TOF offsetsCoarse matching of TOF offsets
0focal-plane X [mm]
1023
TO
F [1
0-1
0 s
ec]
arb
. off
setS
2762
1382
0focal-plane X [mm]
1023
TO
F [1
0-1
0 s
ec]
arb
. off
set
2762
1382
PPAC sections have different TOF offsets
→ need to match them
…however, we may still have an arbitrary common TOF offset
BBquadrupolequadrupole/B/Bdipoledipole optimization optimization
focal-plane X [mm]72 101
3
R/v
[arb
. u
nit
s]
Xfp [mm]129 458
(Bq/Bd)1/2=0.93
(Bq/Bd)1/2=0.96
(Bq/Bd)1/2=0.99
Fine matching of TOF offsetsFine matching of TOF offsets& removal of common TOF offset& removal of common TOF offset
R/v [arb. units]
Xfp ≥ 900
800 ≤ Xfp < 900
700 ≤ Xfp < 800
600 ≤ Xfp < 700
500 ≤ Xfp < 600
400 ≤ Xfp < 500
300 ≤ Xfp < 400
200 ≤ Xfp < 300
100 ≤ Xfp < 200
Counts
Cuts from Xfp vs R/v
D/R [arb. units]
TO
F [1
0-1
0 s
ec]
arb
. off
set
(*) Also check Xfp-R/v plot: a nonzero common TOF offset warps the (supposed-to-be) straight horizontal traces.
(*)
Z selectionZ selection
Range in IC [arb. units]
Energ
y r
ele
ase
in IC
[arb
. u
nit
s] Mg Na Ne
F
O
qB selection - a first qR/v spectrumqB selection - a first qR/v spectrum
qintR/v [arb. units]
Z=10, qint=10
Z=10, qint=9
Z=10, qint=8
counts
22Ne(must be)
17.59Ne ???Must be more careful in selecting events
mv2/R = qBv →
mv2/2 = 1/2 qB Rv
m = qB R/v
DR/TOF [arb. units]
Energ
y in IC
[a.u
.]
Neon
q=10+
q=8+
q=9+
EIC/v2 [arb. units]
R/v
[arb
. u
nit
s]
Neon
EEICIC/v/v22 vs R/v plots vs R/v plots
qintR/v [arb. units] qintR/v [arb. units]
Z=10, qint=10
Z=10, qint=9
Z=10, qint=8
counts
Without (E/v2,R/v) bananas With (E/v2,R/v) bananas
EIC/v2 [arb. units]
R/v
[arb
. un
its]
Neon(E/v2,R/v) bananas give the possibility to remove spurious peaks.
They may also serve as a tool to separate charge states.
Recognizing peaks - aligning R/v Recognizing peaks - aligning R/v spectraspectra
qint 7 8 9 10 11
“qexp” (**)
7.22 8.15 9.08 ≡1010.9
1
R/v spectra corresponding to different charge states can be aligned just by a scaling (the scaling factor being, in principle, the charge).
(**) If you find it downright outrageous to think of “fractional charges”, you might as well use integer scaling factors – along with nonzero offsets, though
(1) A=23 from comparison with Z=10, qint=10 (*) spectrum(2) A=23 from comparison with Z=11, qint=10 spectrum
(*) qint values are determined – comparatively – by looking at traces’ slopes in R•v vs E IC plot
(3) A=26 from comparison with Z=11, qint=10,11 spectra
Once spectra corresponding to (common Z, but) different qint‘s are aligned, they can be summed and calibrated.
Z=12, qint=10
Z=11, qint=10
Z=11, qint=11
Z=12, qint=11
qintR/v [arb. units]
counts
(1)
(2)
(3)
(3)
One last check: XOne last check: Xfpfp vs mass vs mass
1424
3102
0 1023Xfp [mm]
100
• m
ass
[a.m
.u.]
FWHM/centroid = 9.8•10-3
Neon
At last… mass yieldsAt last… mass yields
mass 21 22 23 24 25
counts 2744 2.2e05 47623 9508 357
mass 18 19 20 21 22
counts 268 301 598 63 8
mass 19 20 21 22 23
counts 94 837 4600 758 102
mass 23 24 25 26
counts 936 548 669 104
mass 25 26 27 28
counts 14 75 46 22
A=20
A=21
A=22
A=23
A=26
Mass [a.m.u.]
Counts
Mg
Na
Ne
F
O
101
106
103
102
101
104
102
103
102
101
102
101
A brief summaryA brief summary
• MCP detector: noise removal & “calibration”
• PPAC detector: usage of cathode signal to enhance efficiency
• Coarse matching of TOF offsets
• Optimization of Bquad/Bdip & fine matching of TOF offsets + Removal of residual TOF common offset
• Z selection
• Charge-state selection from R•v-EIC , E/v2-R/v plots
• Alignment of R/v spectra
• Calibration of qR/v spectra → mass spectra
One needs not worry about scaling the TOF’s (to their “true” value) if he’s happy with mass spectra.
But to get γ-ray energies and Q-values right he has to.
Part 2Part 2
Gamma spectraGamma spectra
Eγ= 350 keV45 counts
Eγ= 777 keV13 counts
Gammas in coincidence with Z=10, Gammas in coincidence with Z=10, A=21A=21
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 1275 keV530 counts
Eγ= 509 keV95 counts
Eγ= 583 keV149 counts
Eγ= 2613 keV95 counts
Gammas in coincidence with Z=10, Gammas in coincidence with Z=10, A=22A=22
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 1770 keV29 counts
Eγ= 1704 keV22 counts
Eγ= 1016 keV98 counts
Eγ= 898 keV29 counts
Eγ= 569 keV321 counts
Eγ= 492 keV45 counts
Gammas in coincidence with Z=10, Gammas in coincidence with Z=10, A=23A=23
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 881 keV20 counts
Eγ= 537 keV24 counts
Eγ= 802 keV80 counts
Eγ= 2784 keV6 counts
Eγ= 1983 keV42 counts
Gammas in coincidence with Z=10, Gammas in coincidence with Z=10, A=24A=24
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 440 keV13 counts
Eγ= 351 keV10 counts
Gammas in coincidence with Z=11, Gammas in coincidence with Z=11, A=23A=23
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 204 keV6 counts
Eγ= 721 keV4 counts
Gammas in coincidence with Z=11, Gammas in coincidence with Z=11, A=25A=25
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 167 keV7 counts
Eγ= 656 keV8 counts
Gammas in coincidence with Z=9, A=20Gammas in coincidence with Z=9, A=20
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 1606 keV9 counts
Eγ= 896 keV20 counts
Eγ= 278 keV26 counts
Eγ= 822 keV16 counts
Gammas in coincidence with Z=9, A=21Gammas in coincidence with Z=9, A=21
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Eγ= 629 keV6 counts
Eγ= 245 keV8 counts
Gammas in coincidence with Z=8, A=20Gammas in coincidence with Z=8, A=20
Eγ Doppler correction with βprojectile-like
Eγ D
opple
r co
rrect
ion w
ith β
targ
et-
like
Level scheme fromNNDC ENSDF database
Part 3Part 3
Q-valuesQ-values
Mass vs Q-value - Z=12Mass vs Q-value - Z=12
Mass [a.m.u.]
-Q [
MeV
]
Mg26 27A=25 28
-Q=-5.7 MeV -
11.1
-10.1-
12.6
-Q=-0.04 MeV -3.6 -4.1 -4.8
22Ne+208Pb→AMg+229-AHg +
n
22Ne+208Pb→AMg+230-AHg
Q-values fromNNDC Q-value calculator
Mass vs Q-value - Z=11Mass vs Q-value - Z=11
Mass [a.m.u.]
-Q v
alu
e [
MeV
]
NaA=23 24 25 26
22Ne+208Pb→ANa+229-ATl + n
22Ne+208Pb→ANa+230-ATl
-Q=-0.8 MeV
-Q=6.1 MeV
-0.9
5.6
-3.4
4.1
-1.4
5.2
Q-values fromNNDC Q-value calculator
Mass vs Q-value - Z=10Mass vs Q-value - Z=10
Mass [a.m.u.]
-Q v
alu
e [
MeV
]
NeA=21 22 23 24 25
22Ne+208Pb→ANe+229-APb +
n 22Ne+208Pb→ANe+230-APb-Q=6.4
MeV
-Q=10.4 MeV
0.0
7.4
2.2
8.9
0.04
8.1
3.9
10.6
Q-values fromNNDC Q-value calculator
Mass vs Q-value - Z=9Mass vs Q-value - Z=9
Mass [a.m.u.]
-Q v
alu
e [
MeV
]
F20A=19 21 22 23
22Ne+208Pb→AF+229-ABi + n
22Ne+208Pb→AF+230-ABi
-Q=16.4 MeV
-Q=21.6 MeV
15.0
19.6
11.5
18.9
13.7
20.6
13.0
21.1
Q-values fromNNDC Q-value calculator
Mass vs Q-value - Z=8Mass vs Q-value - Z=8
Mass [a.m.u.]
-Q v
alu
e [
MeV
]
O18A=17 19 20 21 22
22Ne+208Pb→AO+229-APo + n
22Ne+208Pb→AO+230-APo-Q=22.3
MeV
-Q=26.7 MeV
18.6
24.6
20.7
25.2
17.6
25.3
21.5
28.4
21.6
30.0
Q-values fromNNDC Q-value calculator
Q-value vs Gammas - Z=8, A=20 Q-value vs Gammas - Z=8, A=20 selectionselection
32 counts
29 counts
-Q=7.5 MeV
-Q=53 MeV-Q=25.3 MeV
Eγ=0 keV
Eγ=1968 keV
-Q value [MeV]
Eγ [
keV
] ta
rget-
like D
opple
r
Eγ=1968 keV
-Q=28.5 MeV-Q=13.0 MeV
Eγ=0 keV
Eγ= 629 keV210Po 8+→8+
Eγ= 245 keV210Po 4+→2+
-Q [MeV]E
γ [
keV
] ta
rget-
like D
opple
r
22Ne+208Pb → 20O+209Po+n corresponds to Q-value = -25.3 MeV [NNDC]
Signature of one-neutron evaporation Signature of one-neutron evaporation following one- or two-neutron pick-upfollowing one- or two-neutron pick-up
-Q ≥ 9.5 MeV
-2.0 ≤ -Q ≤ 9.0 MeV
Eγ [keV] target-like Doppler
counts
Selection: Z=10, A=23
207Pb 5/2-→1/2-
570 keV207Pb 3/2-→1/2-
898 keV207Pb 7/2-→5/2-
1770 keV
206Pb 2+→0+
803 keV
22Ne+208Pb → 23Ne+206Po+n corresponds to Q-value = -8.9 MeV [NNDC]
2n pick-up
1n pick-up
23Ne23Ne
206Pb
206Pb
Understanding the Q-value spectrum in Understanding the Q-value spectrum in coincidence with the detection of coincidence with the detection of 2222NeNe
22Ne+208Pb → 22Ne+207Pb+n corresponds to Q-value = -7.4 MeV [NNDC]
207Pb 5/2-→1/2-
570 keV
208Pb 583 keV208Pb 511 keV
Eγ [keV]co
unts
-3.5 ≤ -Q ≤ 1.0 MeV
3.5 ≤ -Q ≤ 7.0 MeV
7.5 ≤ -Q ≤ 36.0 MeV
22Ne 2+→0+
wrong Doppler
208Pb 3-→0+ 2615 keV
208Pb 51-→3- 583 keV
208Pb 52-→51
- 511 keV
Eγ [keV] target-like Doppler
counts
-5-10
-15
0 5 10 15 20 25 30 35 40 45
Q-value [MeV]
counts
101
103
102
104
101
102
Maximal EIC
Coincidence with CLARA
Thank Nicu for
• training
• additional programming
• standing the hassle that I gave to him
The end
2n pick-up
1n pick-up
23Ne23Ne
206Pb
206Pb
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