ACTIVE TARGET MAYA

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ACTIVE TARGETMAYA
New detection technique Study nuclei far from
stability
H. Savajols GANIL/TRIUMF Isao Tanihata (TRIUMF)
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Active Target
Concept Target becomes a good resolution
detector
Detector gas H2, D2,3He, 4He, C4H10 ... 3-D
tracking, Range Energy losses of particles
Reaction plane
Pdif
?
Pinc
Prec
?
Detection plane
? 
? f(???)
? Very high efficiency ? Large range of center
of mass angles ? Low particle thresholds ?
Large range recoil energy ? Thick target ?
104-5 Hz
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MAYA
Z Y X
beam
C.E. Demonchy, thesis T0306, Dec 2003, University
of Caen C.E. Demonchy et al. J. Phys. G 31 (2005)
S1831
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MAYA principle
the projectile makes reaction with a nucleus of
the gas.
there is a beam detector before MAYA, to start
the DAQ.
the light scattered particles do not stop inside,
and go forward to a wall made of 20 Si detectors,
where they are stopped, and identified.
cathode
wall of Si detectors
COG over 3 axes
anode amplification area.
5 mm
segmented cathode
the product leaves enough energy to induce an
image of its trajectory in the plane of the
segmented cathode.
we measure the drift time up to each
amplification wire. The angle of the reaction
plane is calculated with these times.
F
tn
t1
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Why 11Li ?

• The first nucleus observed to have a neutron
  halo.
• Very weakly bound system.
• Extend beyond the classical limit.
• The best two-neutron halo nucleus
• Looks like 9Li n n.
• 9Lin nor nn make a bound state.
• Two different orbitals (p1/2 and s1/2) are mixed
  half and half in halo neutrons.
• TRIUMF has the highest-intensity low-energy beam
  of 11Li in the world now.
• It is the time and this is the place to study
  11Li in detail leading the world.

borromean
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Experiments

• E1055
• p(11Li, 9Li) t at 26.5 MeV
• d(9Li, 9Li) d at 26 MeV
• E1078
• p(11Li, d)10Li at 49.5 MeV
• p(11Li, n)11Be (12Li IAS)

after the reaction
incident
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11Li(p,d)10Li event simulation
qCM75

• Ebeam 4 MeV/n
• C4H10 _at_ 0.5 atm
• Range (11Li ) 22.3cm
• r 29 mg/cm2

10Li ? 9 Li n
11Li
Coincidence d and 9Li inside MAYA
d
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11Li(p,d)10Li event simulation
qCM100
10Li ? 9 Li n
11Li
d
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MAYA_at_TRIUMF
ISAC2
ELECTRONICS
MAYA
GHS
PC CONTROLER
DAQ
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First spectra
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A design of the SEBT beam line
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Outlook
EURONS ACTAR JRA 1
GANIL (AC) / DAPNIA / CENBG CCLRC DARESBURY
(FC) U. LIVERPOOL (AC) / U. BIRMINGHAM U.
SANTIAGO DE COMPOSTELA (AC) / GSI / INP CRACOW
( associated participant)
TACTIC A New Detector for Nuclear Astrophysics
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IAS of 12Li ? Resonant elastic scattering 11Li
p
V.Z.Goldberg,Phys.At.Nucl.56,1167(1993) F.DeOlivei
ra, EPJA24,237(2005)

• ? Resonances occur in the nucleus 12Be
• 11Lip ?12Be (T3) ? 11Li p
• EIAS DEC Sn 2.8 MeV
• Sn(12Li) - 1.2 MeV DECZ/A1/3 1.5 MeV

? 8He p ? 9He (IAS) Interference between
resonance and potential scattering ?(ER, ?R, Jp)
?
IAS
Sn-1.2MeV
Eres2.8MeV
25.8 MeV
12Li (T3)
(T5/2)
(T5/2)
(T3)
3/2-
23.01MeV
24.6 MeV
11Lin


11Lip
5.7MeV
(T3/2)
4.5MeV
½-
Level Scheme
½
Sp23MeV
2.7MeV
11Be n
Preliminary
2.09MeV (2)
Sn3.16MeV
800keV
12Be (T2)
C.E.Demonchy, Thesis T0306 Caen
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MAYA resolution
Projected trajectories
Range measurement
Elastic scattering event
p
8He
8He
8He p _at_ 3.9 A.MeV

• ? Range resolution 1 ? Position resolution
  1 mm
• ? Angular resolution 0.7 deg ? Charge
  resolution 10
• ? vertex resolution 3 mm

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MAYA ID
8He(p,x)y _at_ 3.5 A.MeV
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MAYA results
8He(p,d)7He _at_ 3.5 A.MeV
Angle integrated cross-section
Projected spectrum
Angular distribution
7He ? 6He n Sn - 440keV (G150keV)
High cross-section
The width and the population cross-section are
energy dependant
W.Mittig et al., Eur. Phys. J. A25, 263 (2005)
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MAYA set-up
11Li(p,d)10Li _at_ 4 A.MeV

• C4H10 _at_ 0.5 atm
• Range (11Li ) 22.3cm
• r 29 mg/cm2

?
?
Coincidence d and 9Li inside MAYA
? area 40ltqCMlt75 d and Li are stopped
inside MAYA ? area 120?ltqCMlt180 d is stopped
in Si qd lt 30 Ed gt 11.6 MeV Li is stopped
inside MAYA
CM
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