The GEANT4 Code Some Results From First Experiment Next Approved Experiment · 2018-07-09 · The SetupTAS ISpec The TASCA Separator *The GEANT4 Code Some Results From First Experiment

SpecTAS IThe Setup

The TASCA Separator

* The GEANT4 Code

*

*

Some Results From First Experiment

Next Approved Experiment

*

*

Lise−Lotte Andersson United Kingdom

TASISpec − Setup, Simulations, Results and Future

SpecTAS I


TASCA − TransActinide Separator and Chemistry Apparatus

Ch. E. Düllmann et al. Phys. Rev. Lett. 104, 252701 (2010)

Dipole

UNILACbeam

Target Qua

drup

ole

Qua

drup

ole

2005 Built

2006−2008 Commissioned

2009 Z=114 produced and identified


The TASCA Separator at GSI

Two available transmission modes

(35 4)%

A. Semchenkov et al. Nuclear Instrum. and Meth. Phys. Res. B 266 4153 (2008).

High Transmission Mode (HTM)

Small Image−size Mode (SIM)

−

+(60 6)%

+

−

J. Gates et al. , submitted to PRC.

SpecTAS I

4 SSSSD (4*32 strips)

1 DSSSD (32+32 strips)

4 Ge Clover (4*4 crystals)

1 Ge Cluster (7 crystals)

TASCA

ER

The Detector Set−up

L−L Andersson et al., Nucl. Instr. and Meth. A 622, 164 (2010)

TASCA in Small Image Mode Spectroscopy


SpecTAS I

Clover

Clover

Cluster

Clover

Clover

The Detector Set−up

Details of the construction



The Full TASISpec Setup in Geant4

Programmed (in great detail) by: L. G. Sarmiento

0 200 400 600 800 1000 1200 1400 1600Eγ (keV)

0

10

20

30

40

50S

imul

ated

Abs

olut

e E

ffici

ency

(%

) simulated

experimental


Comparing Experiment With Simulations

133Ba

152Eu

Relative gamma−ray efficiency with source on holder

(Compare the shape of the two curves)

0 200 400 600 800 1000 1200 1400 1600Eγ (keV)

0

10

20

30

40

50

60A

bsol

ute

Effi

cien

cy (

%)

simulation with source on holdersimulation with source implanted into the DSSSD

180

160

140

120

100

80

60

40

20

0 10 20 4030 50 60

0

10

20

30

40

50

60


Comparing Simulations With Simulations

Different gamma−ray efficiency in different positions

133Ba152Eu

0 200 400 600 800 1000 1200 1400 1600Eγ (keV)

0

10

20

30

40

50

60A

bsol

ute

Effi

cien

cy (

%)

simulation with source on holdersimulation with source implanted into the DSSSDABSOLUTE experimental efficiency

180

160

140

120

100

80

60

40

20

0 10 20 4030 50 60

0

10

20

30

40

50

60


Comparing Experiment With Simulations

133Ba152Eu

Absolute efficiency comparison!!!

E * E’ m ce2

E’ − E = (1 − cos )θCompton Scattering:

Min

Max


There are no compton shields in the setup

Limiting Background and "False" Coincidences

2) Cross detector add−back (som combinations are more likely)

The limited geometric angles involved in scattering

gives defined ratios for the two energies!

1) Internal Add−back (between crystals in same detector)

SpecTAS I

*

* Total beam integral 2.4E18

to some 25% of the collected data

207 48Pb( Ca, 2n) No253

Results from a subset of runs, corresponding

* First main beam experiment run in 2010


The beamtime

5500 6000 6500 7000 7500 8000 8500 9000 α - particle energy (keV)

0

2000

4000

6000

8000

10000

12000

Yie

ld (

Arb

itrar

y U

nits

)

249 F

m

253 N

o

245 C

f

211 P

o

211 P

o*

253 F

m

211 B

i

Alpha Particles Detected in the DSSSD

(In total 480 000 alpha from 253No)

some 120 000 alpha particles7.9−8.2 MeV:

DSSSD p−side Beam off alpha spectrum


7.00 7.20 7.40 7.60 7.80 8.00 8.20 8.40Alpha Energy (MeV)

0

5

10

15Y

ield

(A

rbitr

ary

Uni

ts)

0 100 200 300 400 500 600 700Eγ (keV)

0.1

1

10

102

103

104

279

7.63 MeV

20 keV FWHM

221

150

669

Q α = 8.15-8.35 MeVX-rays

Eγ = 667-673 keV


A. Lopez−Martens et al. Nuclear Physics A, in press.

Gates clearly show new(ish) gamma−ray transition at 669 keV

Alpha decaying 253No

F. Hessberger et al. Eur Phys J. D 45 33 (2007).

0

5

10

15

0

5

10

15

Yie

ld (

Arb

itrar

y U

nits

)

0 100 200Eγ (keV)

0

5

10

15

163

221

163+58=221

α (58) = 51.4tot

α (71) = 28.4tot

α (129) = 8.3tot

No253


Generous gate on the 58 keV transition

(Cross addback)

(Internal addback)

(No addback) α

Alpha Gamma−Gamma Coincidences and Addback

58

71129

221279

150

0

50

100

0 100 200 300 400 500 600 700Eγ (keV)

0

50

100

150

Yie

ld (

Arb

itrar

y U

nits

)

399

338

18815

1K

β 1

35,1

37,1

40

K α

1 1

21K

α2

115

109

?

166

?76

45439

4

266

?25

8 ?

K β

140

, 141

, 145

K α

2 1

19K

α1

125


Gate: 119, 125 keV

Gate: 115, 121 keV

253Md

253Fm

Gated prompt on p−side DSSSD <600 keV + X−rays

Triple Coincidences

0 100 200 300 400 500 600 700 800

0

50

100

150

0 100 200 300 400 500 600 700 800Energy (keV)

0

50

100

150

200

Yie

ld (

Arb

itrar

y U

nits

)

399

266

K= 257 keVL= 373 keVL= 240 keV

K= 124 keV

338

K= 196 keVL= 312 keV

K

L

K

L

K

L

188

K= 46 keVL= 162 keV

K

L


253Fm comparison: All Ge detectors vs Si box detectors

Conversion Electrons and Gamma Rays

Predicted by

BrIcc v2.2b

NEW

M1 at 200 keV: K−conversion coefficient ~10!

E2 at 100 keV: L−conversion coefficient ~50!

K X−rays: ~ 150 keV

L X−rays: ~ 30 keV

Preference: odd−A nuclei/chains!

~0 keV

~0keV

~100−500 keV

α−dec

ay

gamma−ray emission or

INTERNAL CONVERSION

IDEA:

Want highly−converted transitions:

=> K and/or L X−rays


Where are we going to go next?

One Step Ahead...

Next Step in SHE experiments: Z Fingerprinting via X−rays

NEEDED: Long Decay Chains && High Production && High Detection Efficiency!

2n

0.1

0.5

1

5

10

243Am−target

30 40 50

3n

115289

1152884n

287115

Cro

ss s

ectio

n (

pb

)

Excitation energy (MeV)

A=287, 288, 289


3n4n

2n

Three different E115 Isotopes Produced

2α

0α

1α

5α

4α

3α

2α

1α

3α

4α

2α

1α

113

285

117

293

115

289

Rg

281

Bh

272

268

268

Mt

276

Rg

280

113

284

115

288

Rg

279

Mt

275

113

283

115

287

267

Bh

271

Rf

Db

Db

Yu. T. Oganessian et al., PRC72, 034611 (2005)

Yu. T. Oganessian et al., PRL 104, 142502 (2010)

Ca,xn)243 Am( 48 291−x 115 − 8 weeks approved!

Spokesperson: D. RudolphYu. T. Oganessian et al., JPG 34, R165 (2007)

V. Zagrebaev, NPA734, 164 (2004).

1) 287−115 decaying with a chain of 5 alphas

1.5 pb => 1 chain/week => 8 chains in total

=> 8*5 = 40 X−ray oppertunities

2) 289−115 confirm daughters in the 293−117

chanis from Dubna. Here ~0.5 pb

A=287, 288, 289

3) E115 alpha−gamma coincidence spectroscopy

Expected 20 decay chains =>100 oppertunities

+ Nuclear structure information

4) 287,288−115 confirmation of previous results


To kill four birds with one stone!

Aims of the Experiment

2α

0α

1α

5α

4α

3α

2α

1α

3α

4α

2α

1α

113

285

117

293

115

289

Rg

281

Bh

272

268

268

Mt

276

Rg

280

113

284

115

288

Rg

279

Mt

275

113

283

115

287

267

Bh

271

Rf

Db

Db

Expected to produce 8 decay chains

N > 1 K−X−ray

X

N ~ 1 K−X−ray

X

N ~ 1 K−X−ray


X

X

X

X=> N ~ 2−3 K−Xrays/chain!

A Scenario of X−rays in the Decay Chain

Nuclear structure arguments + numbers include realistic conversion factors

The populated excited state will alpha decaydirectly (not via groundstate)

The alpha populates the ground state

3α

4α

2α

1α

Rg

279

Mt

275

113

283

115

287

267

Bh

271

Db

180

160

140

120

100

80

60

40

20

0 10 20 4030 50 60

0

10

20

30

40

50

60

SpecTAS I

α −efficiency ~80%

4+1 segmented Ge detectors*

* Small−image mode => compact focal plane

* High segmentation => 192 Si strips

* Multi−coincidence capabilities

=> suitable for SHE experiments


γ

A versatile SHE spectroscopy setup!

−efficiency > 50% @ 150 keV

(mm)Z identification of E115!

No alpha decays253

Documents

The GEANT4 Code Some Results From First Experiment Next Approved Experiment · 2018-07-09 · The SetupTAS ISpec The TASCA Separator *The GEANT4 Code Some Results From First Experiment