Gretina science msu_superuser_mtg_aug_2011_riley_published

Joint User Workshop, MSU, August 2011

GRETINA: The Science

Mark Rileyon 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.


Yes Mark, the past 100 years have been pretty special and the future looks exciting too! Good luck with your talk. Best,Ernest.

“It seems reasonable to suppose that the deflexion through a large angle is due to a single atomic encounter…. the atom must be a seat of an intense electric field..”

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


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

GRETINA capabilities

• High position resolution

• High efficiency• High P/T• High counting rate• Background rejection

Experimental conditions Large recoil velocity– Fragmentation– Inverse reaction

Low beam intensity

High background rate Beam decay Beam impurity

Especially for Radioactive Beam Facility (FRIB)


17 Key Science Topics (NSAC 07 Symons Report on FRIB)

• Example:GRETINA/GRETA• 1. Shell Structure X• 2. Superheavies X• 3. Skins X• 4. Pairing X• 5. Symmetries X• 6. EOS• 7. r-process• 8. 15O(a,g) X• 9. 59Fe(n,g) X• 10. Medical• 11. Stewardship ?• 12. Dipole Moment• 13. Limits of Stability• 14. Weakly bound X• 15. Mass Surface• 16. rp-process X• 17. Weak interactions

“The detection of γ-ray emissions from excited nuclei plays a vital and ubiquitous role in nuclear science.” (2002 LRP)

X


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

http://www.physics.fsu.edu/GRETINA/gretina_newsletter_8.pdf

http://www.physics.fsu.edu/GRETINA/gretina_newsletter_8.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, 2007University of Richmond, Richmond, Virginia

Final Report on GRETINA webpage


Commissioning Runs with GRETINA at the BGS:Spectroscopy of the Heaviest Elements

Rod Clark (LBNL)

A Marvelous Physics Opportunity!


MM

HF

RMF

Different Theories, Different Shell Gaps

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

Another approach is to testmodels by examining detailsof properties and behaviorof nuclei with Z>100


How all the Excitement Started!


SHE Current Status


A Land of Opportunity


Tracking the Orbitals


BGS+GRETINA

GRETINA+BGS

GS+FMA(State of art)

• New generation of prompt transfermiumgamma-ray spectroscopy.• Detailed g-g spectroscopy on even-evenZ>100 nuclei possible.• g-spectroscopy on odd-A nuclei• g-spectroscopy of Rf (Z=104) possible(50Ti+208Pb→256Rf+2n with σ~20 nb).

30

2000

254No (Z=102)


Gamma-ray spectroscopy of Rutherfordium

50Ti+208Pb→256Rf+2n

σ~20 nb

25

Counts

6+→4+

Energy (keV)

Assumptions for simulation:sTOT = 1 barnTarget = 0.5 mg/cm2

Beam Current = 50 pnAe g / crystal = 0.0067Mg = 10→ 30.3 kHz/crystal

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

The centenary of the Rutherford model (1911).


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• Resolution of issues

Unanimous agreement on:• physics priorities• order of experiments• details of experiments.


The Set-Up


Latest photos from the BGS cave


GRETINA at NSCL

Overview photograph of S800

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


Gretina advantage over SeGA

Efficiency (1.3 MeV) 2% 8% Resolution x 1/5

GRETINA = Red

SeGA or Gammasphere

Improved Areas include: Inelastic proton scatteringOne-nucleon knockout, two-nucleon knockoutCoulomb excitationLifetime measurements


In-beam test at MSU

Dopplercorrection

E/E

crystal 10%

segment 5%

tracking 2%

2+

Gamma - 28Si coincidence

E g (keV)

• Demonstrated coincidence measurement using

time-stamp technique

• Obtained effective position resolution of 2.2 mm

36Ar at 86 MeV/u, v/c = 0.4 Be target, 0.54 mm(100mg/cm2) thick PIII in coincidence with S800


Performance example

Gamma-ray energy (2keV/channel)

30Na from 32Al Beam

30Na from 30Mg Beam

340

370410250

175

190

150

140

340

370410

250

175

770430 (3+--2+)

Simulation SeGA Simulation GRETINA

30Mg (pn) → 30Na (100 MeV/u) v/c=0.43charge exchange reactionGamma-gamma coincidence

NSCL data SeGA (E. Rodriguez-Vieitez et al.)

n-rich nuclei from fragmentation reactions

Data from SeGA

4 × efficiency1/5 × Doppler width


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 NSCLPAC36 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

• Technical

34

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.

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) ORsingle 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.


138Ce@480MeV

A Science opportunity lies ABOVE the yrastline

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

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

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=G.Rainovski

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=N.Pietralla

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=T.Ahn

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=C.J.Lister

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=R.V.Janssens

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=M.P.Carpenter

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=S.Zhu

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=C.J.Barton

http://www.nndc.bnl.gov/nsr/fastsrch_act2.jsp?aname=C.J.Barton


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 SelectionThe GRETINA Advantages:

Compactness helps overall efficiency (eg-eFMA)Count-rateDoppler Reconstruction ( >3.5 MeV g-rays)


GRETINA@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.

FMA


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.

Deep-inelastic products

Fission products

Angular distribution

Deep-inelastic products

Fission products

Mass distribution

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

Thin target

Thick target


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/

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