Gretina science msu_superuser_mtg_aug_2011_riley_published

GRETINA: The Science

Mark Riley
on behalf of the GRETINA/GRETA Advisory
Committee and the Project Contract
Manager, I.Y. Lee

Thanks to K. Lister, IY Lee, A. Gade and R. Clark
for help with slides.
Joint User Workshop, MSU, August 2011

The Scattering of α and β
Particles by Matter and the
Structure of the Atom
E. Rutherford, F.R.S.*
Philosophical Magazine
Series 6, vol. 21
May 1911, p. 669-688

“It seems reasonable to
suppose that the deflexion
through a large angle is due
to a single atomic
encounter…. the atom must Yes Mark, the past 100 years
be a seat of an intense have been pretty special and
electric field..”
the future looks exciting too!
Joint User Workshop, MSU, August 2011 your talk.
Good luck with

Rutherford’s Lab in Manchester ~1910


Niels Bohr

“Prediction is very
difficult, especially
about the future.”


Evolution of g-ray detector
technology

The calculated resolving power is a measure of the ability to
observe faint emissions from rare and exotic nuclear states.


Evolution of Gamma-Ray
Spectroscopy
• New Detector Systems = New Physics


g- ray tracking is essential
Especially for Radioactive Beam Facility (FRIB)
GRETINA capabilities Experimental conditions

• High position resolution Large recoil velocity
– Fragmentation
– Inverse reaction

• High efficiency Low beam intensity
• High P/T
High background rate
• High counting rate
Beam decay
• Background rejection
Beam impurity


17 Key Science Topics
(NSAC 07 Symons Report on FRIB)
• Example: GRETINA/GRETA
•
•
1. Shell Structure
2. Superheavies
X
X
“The detection of γ-ray
•
•
3. Skins
4. Pairing
X
X
emissions from excited
•
•
5. Symmetries
6. EOS
X nuclei plays a vital and
•
•
7. r-process
8. 15O(a,g) X
ubiquitous role in
•
•
9. 59Fe(n,g)
10. Medical
X
X
nuclear science.”
•
•
11. Stewardship
12. Dipole Moment
? (2002 LRP)
• 13. Limits of Stability
• 14. Weakly bound X
• 15. Mass Surface
• 16. rp-process X
• 17. Weak interactions


Newsletter #9: Summer 2011
• These go back ~ 10
years and are a good
source of info on the
development of the
GRETINA/GRETA
project.
• Useful links too to
many of the recent
workshops.
• Join the user group!
• http://www.physics.fsu.edu/GRETINA/
gretina_newsletter_9.pdf

Recent Science Meetings
involving GRETINA/GRETA
• GRETINA at BGS Science Workshop, LBNL, April 23-
24, 2009
• Workshop ―Step Forward to FRIB‖ ANL, May 30-31, 2009.
• ATLAS Users Workshop August 8 - 9, 2009
• FRIB collaboration meetings, MSU August 10, 2009.
• NSCL User Workshop, August 10-11, 2009.
• Workshop on Physics Opportunities with GRETINA, Joint APS
DNP/ PSJ meeting, Hawaii ,October 13–17, 2009.
• The FRIB Equipment Workshop, MSU, Moving Forward with
GRETA, Feb, 2010
• GRETINA at the BGS: Second Science Workshop at
ANL, Oct, 2010
• Superuser Workshop at MSU, Aug 18-20, 2011.

GRETINA Physics Working Group Workshop

―Optimizing GRETINA Science:
A workshop dedicated to planning the first rounds of operation‖
October 14 + 15, 2007
University of Richmond, Richmond, Virginia

Final Report on
GRETINA webpage

A Marvelous Physics Opportunity!

Commissioning Runs with GRETINA at the BGS:
Spectroscopy of the Heaviest Elements
Rod Clark (LBNL)


Different Theories, Different Shell Gaps

Recent surprise: Dubna (Russia) HF
claim observation of new elements RMF
up to Z=118. Created with much
greater ease than expected. Direct
information on quantum shell MM
structure.

Another approach is to test
models by examining details
of properties and behavior
of nuclei with Z>100


How all the Excitement Started!


SHE Current Status


A Land of Opportunity


Tracking the Orbitals


BGS+GRETINA
GS+FMA
30 (State of art)

2000
• New generation of prompt transfermium GRETINA+BGS
gamma-ray spectroscopy. 254No (Z=102)
• Detailed g-g spectroscopy on even-even
Z>100 nuclei possible.
• g-spectroscopy on odd-A nuclei
• g-spectroscopy of Rf (Z=104) possible
(50Ti+208Pb→256Rf+2n with σ~20 nb).


Gamma-ray spectroscopy of Rutherfordium

The centenary of the Rutherford model (1911).

25 50Ti+208Pb→256Rf+2n
Assumptions for simulation:
sTOT = 1 barn 6+→4+ σ~20 nb
Target = 0.5 mg/cm2

Counts
Beam Current = 50 pnA
eg / crystal = 0.0067
Mg = 10
→ 30.3 kHz/crystal
Energy (keV)

Possible to push up to Sg (Z=106) – cross section ~1nb

GRETINA Advisory Committee View

 To seize this opportunity we recommend that:
 A single collaboration should be formed to perform,

analyse and publish these experiments.
 Rod Clark (LBNL) and Teng-Lek Khoo (ANL) should be

co-spokespersons.
 And of course all this would not be possible without the

essential role of Ken Gregorich + BGS Group

Two very productive
workshops held at
LBNL (2009) and ANL
(2010).

GRETINA/BGS Collaboration

• Aims of experiments
• Running of experiments
• Rights and responsibilities
• Publication and dissemination Unanimous agreement on:
• Resolution of issues • physics priorities
• order of experiments
• details of experiments
.


The Set-Up


Latest photos from the BGS cave


GRETINA at NSCL
• Position at S800 target center
• Modules can be placed at 58.3º (4
positions), 90º (8), 121.7º (4), and
148.3º (5).

Overview photograph of S800

Gretina advantage over SeGA
Efficiency (1.3 MeV) 2%  8% Resolution x 1/5

Improved Areas include:
Inelastic proton scattering
GRETINA = Red
One-nucleon
knockout, two-nucleon
knockout
Coulomb excitation
Lifetime measurements
SeGA or Gammasphere


In-beam test at MSU
 36Ar at 86 MeV/u, v/c = 0.4
 Be target, 0.54 mm(100mg/cm2) thick
 PIII in coincidence with S800
• Demonstrated coincidence measurement using
time-stamp technique

• Obtained effective position resolution of 2.2 mm
Gamma - 28Si coincidence

2+
Doppler E/E
correction
crystal 10%
segment 5%
tracking 2%
Eg (keV)

Performance example
n-rich nuclei from fragmentation reactions
Simulation SeGA Simulation GRETINA
150 340
4 × efficiency
140 30Na from 1/5 × Doppler width
175 32Al
370 Beam
190250 410

175
30Nafrom 30Mg (pn) → 30Na (100 MeV/u)
250 340 30Mg Beam
v/c=0.43
Data from SeGA
370 charge exchange reaction
410 430 (3+--2+)
770
Gamma-gamma coincidence

NSCL data SeGA
Gamma-ray energy
(2keV/channel) (E. Rodriguez-Vieitez et al.)


NSCL PAC 36, July 2011

• Meeting 36 of the NSCL Program Advisory
Committee (PAC 36) was held on July 11–
12, 2011 to consider 34 proposals for 5245
hours of beam time at the NSCL Coupled
Cyclotron Facility.
• The PAC recommended allocation of 3025
hrs for 19 experiments.


PAC 36 at NSCL:
Police reconstruction

The demand for beam time with GRETINA was
rather high!

GRETINA Science at NSCL
PAC36 Approved Experiments
• 11007—Weisshaar, D. et al.
Commissioning of GRETINA + S800 spectrograph at NSCL
• 11013—Iwasaki, H. et al.
Collectivity at the N=Z line and a novel plunger method
• 11015—Gade, A. et al.
Gamma-ray spectroscopy of neutron-rich Ti isotopes
• 11017—Stroberg, R. et al.
Single-particle structure of neutron-rich Si isotopes
• 11021—Zegers, R.G.T. et al.
Search for isovector giant monopole resonance
• 11024—Montes, F. et al.
Important 58Zn excitation energies for rp-process

GRETINA Science at NSCL
PAC36 Approved Experiments
• 11025—Bentley, M. et al.
Gamma and gamma-gamma spectroscopy of mirror nuclei
• 11029—Fallon, P. et al.
Gamma-gamma spectroscopy of neutron-rich Mg nuclei
• 11031—Wiedenhoever, I. et al.
Triple configuration coexistence in 44S
• 11035—Campbell, C. et al.
Anomalous quadrupole collectivity in light Sn isotopes
• 11036—Sorlin, O. et al.
Is 34Si a "Bubble" Nucleus?
• 11037—Riley, L. et al.
Inelastic Excitations Beyond 48Ca

GRETINA @ ATLAS


GRETINA at ANL
• Science
There is a compelling case for conducting a campaign in which CARIBU
beams are excited using Coulomb Excitation.

There is a compelling case for trying to approach 100Sn, and good cases
for studying very heavy nuclei and neutron-rich nuclei via deep inelastic
transfer.

• Technical
Digital Gammasphere and GRETINA have some overlapping features.
Both have some unique niches which should be exploited. It is NOT a
case of one being better than the other.


The GRETINA Niche

Superior Doppler Reconstruction

Compact

Polarization

High Energy Gamma Rays

Coulomb Excitation
A surgical tool for measuring collectivity of nuclei:-

Quantitative

Good Cross-sections

Can be adopted to probe beam particles (CARIBU beams)

Can be tuned for multi-step ( evolution of mean field with spin) OR
single step (b- g- bands, mixed symmetry, new modes?)
BUT

Emitting nuclei are recoiling fast, >10% c, so good Doppler correction
needs a good measurement of the emitter velocity.

A Science opportunity lies ABOVE the yrastline

138Ce@480MeV

G.Rainovski, N.Pietralla, T.Ahn, C.J.Lister, R.V.F.Janssens, M.P.Carpen
ter, S.Zhu, C.J.Barton III Phys.Rev.Lett. 96, 122501 (2006)

GSFMA155 Study of Mixed Symmetry States through
138Ce(12C,12C) at 4.5 MeV/u

Stable Beam Coulex with GRETINA

Resolution can be improved with GRETINA AND “Super-Chico”


100Sn Region
Fusion-evaporation is arguably the best way there.

The challenges are:

Low production cross-section.
Channel Selection
The GRETINA Advantages:
Compactness helps overall efficiency (eg-eFMA)
Count-rate
Doppler Reconstruction ( >3.5 MeV g-rays)

GRETINA@FMA

FMA

GRETINA at backward angles to avoid neutrons and beam-dump gamma rays

FMA at “30-cms” position for high efficiency recoil collection. (90-cms with GS)

Space for target wheel.


Heavy Nuclei
GRETINA and AGFA will be a powerful combination.

HOWEVER

There are NICHE studies with FMA, when MASS Selection is essential.

Two isomers which both fission, with 3.7 and 43 ms lifetimes. Which IS the isomer? Is
the isomer more long-lived than the ground state? Is it a K-Isomer? Can we find bands
built on both states? Can we find decays between them?
Cross sections are small, (7 and 12 nb) but possible.


Deep Inelastic Scattering
Superior Doppler Reconstruction will also help in Multi-nucleon and
deep inelastic transfers.
Angular distribution
Fission products
Thin
target

Deep-inelastic products

Mass distribution Thick
target
Fission products

Deep-inelastic products

However, for the best
reconstruction, one needs
recoil VELOCITY vector

GRETINA to GRETA for FRIB

CAD model

It has been called
“A jewel in the crown of
FRIB”


2007 Long Range Plan

……. Thus the construction of
GRETA should begin upon
successful completion of GRETINA.
This gamma-ray energy tracking
array will enable full exploitation of
compelling science opportunities in
nuclear structure, nuclear
astrophysics, and weak
interactions.


2007 Long Range Plan

……. Thus the construction of
GRETA should begin upon
successful completion of GRETINA.
This gamma-ray energy tracking
array will enable full exploitation of
compelling science opportunities in
nuclear structure, nuclear
astrophysics, and weak
interactions.

Let’s keep the momentum
going!

Summary
• Gamma-ray tracking arrays will have a large impact
on a wide area of nuclear physics.
• GRETINA is completed, engineering runs have
been carried out, commissioning runs start soon.
• Exciting period of physics campaigns scheduled
through 2013.
• GRETINA/GRETA will be a major instrument for
FRIB.
http://www.physics.fsu.edu/GRETINA/NewsUpdate/

Become a friend on Facebook!

Gretina science msu_superuser_mtg_aug_2011_riley_published

Recomendados

Recomendados

Más contenido relacionado

Similar a Gretina science msu_superuser_mtg_aug_2011_riley_published

Similar a Gretina science msu_superuser_mtg_aug_2011_riley_published (20)

Último

Último (20)

Gretina science msu_superuser_mtg_aug_2011_riley_published