SWEEPING IONS AWAY…

HRS considerations for MoNA-LISA

SOME THINGS TO REMEMBER…

• Speaking for the MoNA Collaboration

OUTLINE

• Physics Goals– Decay energy, structure near the drip line

– Neutron correlations (dineutron)

– Coulex, inverse (n,g) reactions

• Description of detector systems– MoNA and LISA

– Timing, tracking

– Energy/loss and PID

• HRS needs– Large acceptances

– High rigidity (7 T•m)

– Clear gap to large angles

– Long flight path

TYPES OF EXPERIMENTS

• One or two proton knockout leading to

unbound states – largest potion

• Neutron correlations in direct 2n-decay

• (d,p) leading to n-unbound states

• Coulex to unbound states – Horvath

SPECTROSCOPY OF NEUTRON-RICH OXYGEN ISOTOPES

The 7.5 MeV state in 24O decays by sequential 2-neutron emission

Phys. Rev. Lett. 100, 152502 (2008)

Phys. Rev. C83, 031303(R) (2011)

Phys. Rev. Lett. 99, 112501 (2007)

Phys. Lett. B 672, 17 (2009)

All levels are based on MoNA results with the exception of the 23O 3/2+ state

2010 Dissertation Award in Nuclear Physics Recipient:Calem R. Hoffman (FSU)

R.V.F. Janssens, News and Views, Nature 459 (2009) 1069

MOTIVATION: 16BE

A. Spyrou, J.K. Smith et al, Phys Rev C84(2011)044309

NuShell, WBP interaction16Be predicted to be: - unbound with respect to 2n decay - bound with respect to 1n decay

Scenario for “true” 2n emission

RESULTS: 16BE – CORRELATIONS

A. Spyrou, Z. Kohley et al, Phys Rev Lett. 108(2012)102501

• First observation of dineutron decay• Further experimental and theoretical work to understand the strong n-n interactions

Sequential 3-body Dineutron

E(n1 + n2) cosθ(n1 + n2)

RESULTS: CORRELATIONS

Jacobi systems

Strong nn correlation observed

Causality cuts applied

Phase-space

as = -18.7 fm

as = -100 fm

T

T

Y

Y

Dineutron model – A. Volya (FSU)EPJ Web of Conf. 38, 03003 (2012).

CURRENT DETECTOR SYSTEMS

• MoNA – 144 (100x10x10)cm3 bars of fast plastic, position sensitive by time difference. (NSF-2001/MRI – $1M)

• LISA – additional 144 bars to increase angular coverage, increasing efficiency for higher excitation energies (NSF-2009/MRI $1.4M)

• Beamline tracking CRDCs (2x – NSCL)

• Sweeper Magnet – FSU/NHMFL

• Sweeper box CRDCs (2x – NSCL)

• Sweeper box ion chamber (NSCL)

• Sweeper box plastic DE-E (NSCL) – to be replace by CsI hodoscopebuilt be N. Frank at Augustana

• All read out via a time-stamping system implemented in FPGAs by P. DeYoung and T. Baumann

REASONS FOR LISA

1n

2nMoNA-LISA

MoNA-LISAMoNA

MoNA

efficiency and resolution improvement

24O 23O + nGeometric Coverage

CURRENT SETUP

WHAT IT ACTUALLY LOOKS LIKE…

PHYSICS OPTIONS WITH FRIB

FIRST OBSERVATION OF 40MG

T. Baumann et al., Nature 449 (2007) 1022

DRIPLINE EXTENDS FURTHER THAN BELIEVED

FRDM

HFB14

Starting with 42Al the p3/2 shell is filled, indicating that 45Al is bound; and even 47Al could be bound (p1/2)

45 47

HRS DESIGN CONSIDERATIONS

• Rigidity of at least 7.3 T•m

– to accept A/Z = 3 at 150 MeV/u

– For HRS and all beamlines leading to it

• Reliable incoming and outgoing tracking

– (efficiency, resolition, and reliability)

• High momentum acceptance 10% or higher

• Resolution of DP/P ~1000

RIGIDITY NEEDS

HRS DESIGN CONSIDERATIONS

• Time of flight

– Need t0 (timing detector by target)

– Need flight path ~15-20 m.

• Clear gap

– 8° forward

– One side to 90° (EOS-Kohley)

EFFECTS OF ACCEPTANCE

HRS REQUIREMENTS FOR MONA-LISA

Sweeper•14 cm vertical gap•11 msr to 32 msr acceptance•15% to 20% in Br

HRS•Similar acceptances•Higher rigidity ~7 Tm•Longer flight path ( > 15 m)•Larger neutron window

SPECIAL THANKS TO

Artemis Spyrou

Paul DeYoung

Zach Kohley

Thomas Baumann

All of the MoNA collaboration

National Science Foundation

PETERS (d,n)