22 Ne@131 MeV + 208 Pb: a PRISMA+CLARA data analysis

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


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 D

opple

r co

rrect

ion w

ith β

targ

et-

like




Gammas in coincidence with Z=9, A=20Gammas in coincidence with Z=9, A=20


Eγ D

opple

r co

rrect

ion w

ith β

targ

et-

like








Eγ D

opple

r co

rrect

ion w

ith β

targ

et-

like


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 [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



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



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



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-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

22 Ne@131 MeV + 208 Pb: a PRISMA+CLARA data analysis

Documents

Transcript of 22 Ne@131 MeV + 208 Pb: a PRISMA+CLARA data analysis