'Fision-Fusion' Reaction Mechanism - ELI-NP

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Nov 29, 2013 (3 years and 11 months ago)

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Peter G. Thirolf, LMU München

The ‘Fission

Fusion‘ Reaction Mechanism:

Using dense laser
-
driven ion beams


for nuclear astrophysics

Outline:



motivation: nucleosynthesis of heavy elements




r process path:
waiting point N=126




ultra
-
dense laser
-
accelerated ion beams




novel reaction mechanism: fission
-
fusion




experimental requirements at ELI
-
NP

Peter G. Thirolf, LMU Munich

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

r process: waiting point N=126

-

waiting point N=126: bottleneck for nucleosynthesis


of actinides

-

last region of r process

close


to stability



r process:



-

path for heavy nuclei far in ‚terra incognita‘


-

astrophysical site(s) still unknown:


core collapse SN II, neutron star merger ?

Au, Pt, Ir,Os

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

-

cold compression of electron sheet, followed by electron breakout


-

dipole field between electrons and ions


-

ions + electrons accelerated as neutral bunch (avoid

Coulomb explosion)


-

solid
-
state density: 10
22
-

10
23

e/cm
3


‘classical’ bunches: 10
8

e/cm
3

Radiation Pressure Acceleration

driver laser

ions

electrons

nm

foil

relativ. electrons

at solid density



~
10
14

x density of conventionally accelerated ion beams

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Exp. Scheme for “Fission
-
Fusion”

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

~ 1 mm

Fission

fragments

Fusion products

Reaction target

Production target

CD
2
: 520 nm

CH
2

~ 70
m
m

232
Th:

~ 50
m


232
Th: 560 nm


APOLLON laser :

1.2
.
10
23

W/cm
2

32 fs, 273 J, 8.5 PW

1.0
.
10
22

W/cm
2

32 fs, 23 J, 0.7 PW

focus: ~ 3
m
m



232
Th

+ p, C


F
L

+ F
H
: beam
-
like fission fragments



beam (~ 7 MeV/u): d, C,
232
Th

target: p, C,
232
Th



d, C +
232
Th



F
L

+ F
H

: target
-
like fission fragments

D. Habs, PT et al., Appl. Phys. B, in print

Peter G. Thirolf, LMU München

Fission Stage of Reaction Scheme

232
Th:

<A
L>

~ 91,
D
A
L

~ 14 amu (FWHM)


D
AL ~ 22 amu (10%)

<Z
L
> ~ 37.5 (Rb,Sr)

F
L

F
H



fission mass distribution:

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011



fusion
-
evaporation calculations (PACE4):





(Z=35,A=102) + (Z=35, A=102): E
lab
= 270 MeV (E* = 65 MeV)


190
Yb (Z=70,N=126): 2.1 mb


189
Yb ( N=125): 15.8 mb


188
Yb ( N=124): 61.7 mb


187
Yb ( N=123): 55.6 mb

Peter G. Thirolf, LMU München

Collective Stopping Power Reduction




























p
D
D
e
e
e
v
k
k
e
v
m
v
m
e
Z
n
dx
dE


ln
ln
4
2
2
2
4
2
eff
binary

collisions

k
D

= Debye wave number

long
-
range
collective

interaction


p

= plasma frequency



Bethe
-
Bloch for individual ion:



reduction of atomic stopping power for ultra
-
dense ion bunches:


-

plasma wavelength (~ 5 nm) « bunch length (~560 nm):




only binary collisions contribute


-

„snowplough effect“: first layers of ion bunch remove electrons


of target foil


-

predominant part of bunch: screened from electrons (n
e

reduced)



reduction

of

dE
/
dx

:
avoids

ion

deceleration

below

V
C
:



allows for thick reaction targets for fusion reactions

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Exp. Scheme for “Fission
-
Fusion”

collective stopping:

~ 1 mm

Fission

fragments

Fusion products

232
Th: ~ 5 mm

CD
2
: 520 nm

232
Th: 560 nm

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Reaction target

Production target

APOLLON laser :


1.2
.
10
23

W/cm
2

32 fs, 273 J,8.5 PW

1.0
.
10
22

W/cm
2

32 fs, 23 J, 0.7 PW

focus: ~ 3
m
m

conventional stopping:

~ 1 mm

Fission

fragments

Fusion products

Reaction target

Production target

CD
2
: 520 nm

CH
2

~ 70
m
m

232
Th:

~ 50
m


232
Th: 560 nm


APOLLON laser :

1.2
.
10
23

W/cm
2

32 fs, 273 J, 8.5 PW

1.0
.
10
22

W/cm
2

32 fs, 23 J, 0.7 PW

focus: ~ 3
m
m



Peter G. Thirolf, LMU München

Fission
-
Fusion Yield / Laser Pulse

laser acceleration (300 J,
e
~10%): normal stopping reduced stopping


232
Th 1.2
.

10
11

1.2
.

10
11


C 1.4
.

10
11

1.4
.

10
11


protons 2.8
.

10
11
1.8
.

10
11


beam
-
like light fragments

3.7
.

10
8

1.2
.

10
11


target
-
like light fragments

3.2
.

10
6

1.2
.

10
11


fusion probability
1.8
.

10
-
4

1.8
.

10
-
4


F
L
(beam) + F
L

(target)


neutron
-
rich fusion products
1.5 4
.

10
4


(A≈ 180
-
190)



laser development in progress:


diode
-
pumped high
-
power lasers: increase of repetition rate

expected

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Towards N=126 Waiting Point



r process path:


-

known isotopes ~15 neutrons away from r process path (Z≈ 70)

0.5

0.1

x



visions:

-

test predictions: r process


branch to long
-
lived (~ 10
9

a)


superheavies (Z≥110)




search in nature ?

-

improve formation predictions


for U, Th

-

recycling of fission fragments


in (many) r process loops ?

-

lifetime measurements:


already with ~ 10 pps



measure:


-

masses, lifetimes, structure


-

b
-
delayed n emission prob. P
n
,n

0.001

s
fisfus

key

nuclei

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Experimental layout

high power

short
-
pulse

laser APOLLON

(gas
-
filled) separator

mirror

target

concrete

shielding



characterization of reaction products


-

decay spectroscopy

(tape) transport

system

detector

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Experimental layout

high power

short
-
pulse

laser APOLLON

(gas
-
filled) separator

mirror

target

concrete

shielding

gas stopping cell

cooler/buncher


Penning trap

mass measurements


(
D
m/m= 10
-
8
)



characterization of reaction products


-

decay spectroscopy



precision mass measurements:


e.g. Penning trap

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

“The Way Ahead”

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011



exploratory experiments :



requirements:



-

RPA target chamber



-

232
Th target development


-

ion diagnostics: Thomson parabola

-

staged approach with tests of crucial ingredients


at existing facilities prior to operation of ELI
-
NP





laser ion acceleration of Th ions




collective effects of dense ion bunches (range enhancement)

Peter G. Thirolf, LMU München

Conclusions



novel laser ion
acceleration (RPA
):



-

generation of ultra
-
dense ion bunches


-

enables fission
-
fusion reaction mechanism




fusion between 2 neutron
-
rich fission fragments


-

reduction of electronic stopping ?


-

may lead much closer towards N=126 r
-
process waiting point




ELI
-
NP: unique infrastructure



-

superior to ‘conventional’ radioactive beam facilities




The Way Ahead:



-

exploratory experiments at existing laser beams


(Thorium acceleration, collective range enhancement..)


-

collaboration has to be formed

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Thanks to the Collaboration:

D. Habs (LMU, MPQ)

T. Tajima (LMU, JAEA/Kyoto)

J. Schreiber (LMU)


M. Gross (LMU)

A.
Henig (LMU)

D. Jung (LMU)

D. Kiefer (LMU)

G. Korn (MPQ)

F. Krausz (MPQ, LMU)

J. Meyer
-
ter
-
Vehn (MPQ)

H.
-
C. Wu (MPQ)

X.Q. Yan (MPQ, Univ. Beijing)


B. Hegelich (LANL, LMU)


V. Liechtenstein (Kurchatov Inst., Moscow)

Thank you for your attention !

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

Peter G. Thirolf, LMU München

Requirements for E1 @ ELI
-
NP:

Floorspace

layout

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

production
-


separation area

measurement area

concrete shielding

18 m

12 m

12 m

15 m

recoil separator:

-

wide momentum acceptance

-

gas
-
filled ?

Peter G. Thirolf, LMU München

Experimental Requirements @ ELI
-
NP

110 m

120 m

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011

E1:

laser
-
induced nuclear reactions




“fission
-
fusion”

experimental areas

Laser

clean rooms

Peter G. Thirolf, LMU München

Cost Estimate

ELI
-
NP Workshop, Bucharest, March 10
-
12, 2011



component cost estimate:

-

laser target chamber: ~ 200 kEUR

-

recoil separator : ~ 5000 kEUR


-

tape station : ~ 150 kEUR

-

decay detectors : ~ 150 kEUR


-

buffer gas cell : ~ 300 kEUR

-

mass analyzer : ~ 300 kEUR


-

electronics, control,


data acquisition : ~ 200 kEUR

total: ~ 6.3 MEUR