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Recent Experimental Results from HELIOS. A new approach to reactions in inverse kinematics. A. H. Wuosmaa Western Michigan University. Why still study nucleon transfer?. Renewed emphasis on transfer reactions with RIBS :

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Recent Experimental Results from HELIOS

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Recent experimental results from helios

Recent Experimental Results from HELIOS

A new approach to reactions in inverse kinematics

A. H. Wuosmaa

Western Michigan University


Why still study nucleon transfer

Why still study nucleon transfer?

  • Renewed emphasis on transfer reactions with RIBS:

    • Properties of nuclei far from stability, esp. near “closed” shells (spins, parities, spectroscopic factors, s.p. energies, residual interactions)

    • Importance of the tensor interaction

    • Test/tune new shell-model interactions

  • Broader applications:

    • e.g. astrophysics, stewardship (“surrogates” for capture reactions)

Life is muchmore difficult with inverse kinematics

and radioactive beams


Evolution of 1 s 1 2 0 d 5 2 splitting outside n 8

Evolution of 1s1/2-0d5/2 splitting outside N=8

?? (1,2,3,4)-

0d5/2 neutron has j(n)=j>

0.74 5/2+

0.33 (0,1)-

0.00 1/2+

0.87 1/2+

?? (1,2)-

0.17 (2,3)-

0.00 5/2+

14B(Sn=0.97)

17O(Sn=4.14)

16N(Sn=2.49)

15C(Sn=1.22)

p(p1/2)2

p(p1/2)

p(p3/2)4

p(p3/2)3

j(p)=j<

attraction

j(p)=j>

repulsion

j(p)=j>

repulsion

j(p)=j<

attraction

=(

J(p),J(n) one j>otherj<:attraction

J(p),J(n) both j>or j<:repulsion


D p reaction in different frames

(d,p) reaction in different frames

OUT

IN

1H

v0

qCM

CM frame

2H

vlab

qLAB

Laboratory frame-

“normal” kinematics

Laboratory frame-

“Inverse” kinematics

vlab

qLAB


The helios approach to inverse kinematics

The HELIOS approach to inverse kinematics

Uniform magnetic field B

Emitted here

z

Beam Axis

Detected here

Cyclotron orbit

We measure:

Elab, z, TOF

We deduce:

ECM ,qCM

For a given state

For two states at

fixed z


Advantages to the helios approach for d p

Advantages to the HELIOS approach for (d,p)

“Conventional” –

measure at fixed qLAB

HELIOS –

measure at fixed z

dEP/dqLAB=175 keV/deg

EP(MeV)

EP(MeV)

5 MeV

1.4 MeV

dEP/dz=17.5 keV/mm

Cos(qCM)

Cos(qCM)

qLAB(deg)

z (m)


Heli cal o rbit s pectrometer helios

HELIcalOrbit Spectrometer -HELIOS

BMAX=2.85 T

2.35 m

0.9 m

Silicon Array

Target

Beam

Laser

rangefinder

X-Y-q positioning

stage

J.P. Schiffer, RIA equipment workshop 1999,

AHW et al, NIMPRA 580, 1290 (2007)

J. C. Lighthall et al, NIMPRA 622, 97 (2010)


Spectrometer completed in august 2008

Spectrometer completed in August 2008


28 si d p 29 si commissioning it works

Excitation energy in 29Si

0.00

A/q=1,

1 turn

protons from 28Si+12C

1.27

2.03

A/q=1, 2 turns

(A/q=2, 1 turn)

Residual a source background

3.62

3.07

4.94

T(ns)

6.38

6.19

6.71

7.79

28Si(d,p)29Sicommissioning-it works!

J. C. Lighthall et al, NIMPRA 622, 97 (2010)


28 si d p 29 si excitation energy spectrum

28Si(d,p)29Si Excitation-energy spectrum

Typical resolution ~ 120 keV FWHM

Best resolution ~ 80 keV FWHM

J. C. Lighthall et al,

NIMPRA 622, 97 (2010)


Exotic behavior in 16 c

Exotic behavior in 16C?

Valence

neutrons

Core

16C

No hindrance, and

no exotic behavior.

Study with 15C(d,p)16C


15 c d p 16 c with helios

15C(d,p)16C with HELIOS

1.5-2M 15C/s @ 8.2 MeV/u

Proton energy-position

correlation

(d,p) samples the

n(1s1/2) content of

the wave functions

for positive-parity states

16C Excitation-energy

spectrum

PRL 105, 132501 (2010)


15 c d p 16 c results

L=0

L=2

L=0

L=2

15C(d,p)16C results

Shell model – WBP

interaction

Experiment

Shell model works well –

no need for exotica!

PRL 105, 132501 (2010)


19 o d p 20 o further into the sd shell

19O(d,p)20O – further into the sd shell

200k-300k 19O/s @ 6.6 MeV/u

Proton energy versus position

20O excitation energy

ν(0d5/2)35/2ν(sd)→ν(sd)4 states in 20O

C. R. Hoffman et al.,

PRC 85, 054318 (2012)


What we can learn from 19 o d p 20 o

What we can learn from 19O(d,p)20O

L=2

L=0+2

Orbital vacancy G+

Cross section (mb/sr)

Center-of-mass angle (deg)

19O excitation energy (MeV)

Solid: L=0; hatched L=2

Angular distributions and

neutron vacancies from 19O(d,p)20O

C. R. Hoffman et al.,

PRC 85, 054318 (2012)


Preliminary excitation energy spectrum

Preliminaryexcitation-energy spectrum

13B(d,p)14B

G<150 keV

G~200 keV

20-40k 13B/s @15.7 MeV/u

Sn=0.969

Broad l=0 and 2 states expected

with Jπ=(0,1,2,3)-

Red – 14B

Blue – 13B

EX (14B) (MeV)


13 b d p 14 b preliminary

L=0

L=2

L=0+2

2- 0.0

13B(d,p)14B Preliminary

L=0

L=2

Shell model with

WBT interaction

1- 0.65

ds/dW (mb/sr)

Experiment

Sn

3- 1.38

(2-)

G~1MeV

Preliminary!

Preliminary!

4- 2.08

OMPs fit 30 MeV d+12C, p+12,13C elastic

scattering at 15 MeV/u

qc.m. (deg)


136 xe d p 137 xe with helios approaching 132 sn

136Xe(d,p)137Xe with HELIOS– approaching 132Sn

Proton energy

versus position

137Xe excitation

energy

B. P. Kay et al,

PRC 84, 024325 (2011)


What we can learn from 136 xe d p 137 xe

What we can learn from 136Xe(d,p)137Xe

136Xe(d,p)137Xe angular distributions and

orbital-energy trends near N=82

B. P. Kay et al,

PRC 84, 024325 (2011)


A variety of measurements

A variety of measurements

  • 28Si(d,p)29Si – Aug. 2008 (first commissioning)*

  • 12B(d,p)13B– March 2009 (RIB commissioning)*

  • 17O(d,p)18O – Aug. 2009 (unbound states in 18O)

  • 15C(d,p)16C – Sep. 2009 (exotic behavior in 16C)*

  • 130,136Xe(d,p)131,137Xe – Nov. 2009 (S.P. states near N=82)*

  • 86Kr(d,p)87Kr – Feb. 2010 (S.P. states near N=50)

  • 14C(6Li,d)18O – March 2010, (a-cluster states in 18O: d not p!)

  • 19O(d,p)20O – Sep. 2010 (structure of 20O)*

  • 28Si(d,3He)27Al, 28Si(d,t)27Si – May 2011 (commissioning of forward-hemisphere configuration)

  • 13B(d,p)14B– Nov. 2011 (structure of 14B)

  • 17N(d,p)18N– March 2012 (structure of 18N)

    *Published or In Press


Summary

Summary

  • HELIOS provides a new approach to studying reactions in inverse kinematics

  • Alleviates problems with light particle identificationand gives improved excitation-energy resolution and straightforward determination of CM quantities

  • Can obtain data with quality approaching that of normal-kinematics measurements

  • The method can be applied to a variety of other inverse-kinematic reactions in addition to (d,p)

  • Other examples are being considered at HIE-ISOLDE, SPIRAL2, ReA3/FRIB


Many thanks to

Many thanks to:

2M. Alcorta, 2B. B. Back, 2S. I. Baker, 1S. Bedoor, 2P. F. Bertone, 3B. A. Brown, 2J. A. Clark, 2,4C. M. Deibel, 5P. Fallon, 6S. J. Freeman, 2C. R. Hoffman, 2B. P. Kay, 2,7H. Y. Lee, 1,2J. C. Lighthall, 5A. O. Macchiavelli, 1,2S. T. Marley, 2K. E. Rehm, 2J. P. Schiffer, 1D. V. Shetty, 8M. Wiedeking

1Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252, USA

2Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

3Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA

4Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824, USA

5Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

6Department of Physics, University of Manchester

7LANSCE-NS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

8Lawrence Livermore National Laboratory, Livermore, California 94551, USA


Recent experimental results from helios

And…

The HELIOS Collaboration

S. Bedoor, J. C. Lighthall, S. T. Marley, D. Shetty, J. R. Winkelbauer (SULI student), A. H. Wuosmaa

Western Michigan University

B. B. Back, S. Baker, C. M. Deibel, C. R. Hoffman, B. Kay, H. Y. Lee, C. J. Lister, P. Mueller, K.E. Rehm, J. P. Schiffer, K. Teh, A. Vann (SULI student)

Argonne National Laboratory

S. J. Freeman

University of Manchester

Work supported by the U. S. Department of Energy, Office of Nuclear Physics, under contract numbers DE-FG02-04ER41320 (WMU) and DE-AC02-06CH11357 (ANL)

Also, special thanks to:

N. Antler, Z. Grelewicz, S. Heimsath, J. Rohrer, J. Snyder


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