Slightly neutron-rich Si isotopes –

an interesting region to be studied

Christoph Langer (Univ. Frankfurt)

CHANDA workshop

November 25th 2015 // PSI

The “traditional“ picture of nuclear physics ...

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

P. Cottle, Nature 465 (2010)

Wik

ipe

dia

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

But, there is interest in “shell evolution“ ...

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

The noisrevni fo dnalsi | island of inversion ...

12

14

10

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Measurements around the “shoreline“ ...T. O

tsuka

et a

l. (20

09

)

ANL

Osaka/RIKEN

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Tiny grains with presolar origin ...

WU

Pre

sola

rG

rain

Da

ta B

ase

0.1% Type C

In collaboration with P. Hoppe et al., Mainz

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Nasa – Cas A – 10 kly - ~1680

Collapse of a massive star and grain formation ...

B. S

. Me

yer, 1

99

5, M

et.

C>O

In collaboration with P. Hoppe et al., Mainz

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Peculiar isotopic abundances on type C grains ...

P.

Ho

pp

e e

t a

l, A

PJL

74

5 (

20

12

)

„Heavy“ Si isotopes „Light“ S isotopes

Xu et al., Met. Soc. Meeting 2012

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

No standard way to explain this untypical behavior

(except of invoked molecule chemistry)

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Idea: implantation of 32Si into the grains ...

M. Pignatari, E. Zinner (†), et al., ApJL 771 (2013)

32SiS

He/CC/Si

n-process [22Ne(α,n)25Mg]: 1018-1019 n cm-3

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

M. Pignatari, E. Zinner (†), et al., ApJL 771 (2013)

Constraining pre-CCSN and CCSN conditions ...

Assuming:

all S is from decay of32Si OR

isotopically normal S

from contamination

ASTRONUCLEAR

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

H. B

ee

r et a

l. NP

A 7

09

(20

02

)

DC

30Si(n,γ)

DC?

MACS?

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

Thomsen et al., PRC 43 (1991) AMS at ENtandem in Aarhus

30Si(n,γ)31Si(n, γ)32Si

DR-3 reactor at Research Center Risø (23d)

σth= 73(6) mb

Conflicting information from other sources!

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

One measurement from 1999 (Krane et al.) gave

only upper limit on thermal cross-section

M. Pignatari, E. Zinner (†), et al., ApJL 771 (2013)

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

32Si(n,γ)33Si

G.

Bo

uto

ux

et

al.

, P

LB

71

2 (

20

12

)

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Example: 32Si(d,p)33Si

Neutron-capture chain on Si isotopes ...

32Si + n

s-wave

nndc, 2015

33Si*

γ

β ̴ 0.20c

32Si

γ

d

33Si

Proposal, NSCL, C. Langer et al.

Beam

Target

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

32Si(n,γ)33Si

G.

Bo

uto

ux

et

al.

, P

LB

71

2 (

20

12

)

Private communication with B. A. Brown

Sn

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

32Si(n,γ)33Si

F.

Kä

pp

ele

re

t a

l.,

Ap

J3

55

(1

99

0)

LSC?

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Neutron-capture chain on Si isotopes ...

FRM II Reactor in Munich

Flux Φ ~ 7x1013 n cm-2 s-1

Needs a fast

insertion/extraction

system (not yet)

htt

ps:

//w

ww

.frm

2.t

um

.de

/en

/th

e-n

eu

tro

n-s

ou

rce

/irr

ad

iati

on

-fa

cili

tie

s/

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI

Summary and Outlook

Kutschera et al. (1992)

Christoph Langer // Univ. of Frankfurt CHANDA workshop // PSI