Matta Natasha Timofeyuk TREX MINIBALL 18 N 7 protons 11 neutrons p 12 1 d 52 3 Lowlying states dominated by proton p 12 1 ID: 582398
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Slide1Slide2
Adrien
Matta
Natasha
Timofeyuk
T-REX, MINIBALLSlide3
18
N –
7 protons
, 11 neutrons p1/21
d
5/23
Low-lying states dominated by: proton( p1/21 ) (d5/23 )J=5/2 or (d5/23 )J=3/2 or s1/21 of which the 1 and 2 from the middle configuration can’t be populated in (d,p)
these levels are confused, in the compilationsSlide4
Neutron-rich pathway through light nuclei in explosive
nucleosynthesis
nitrogen
and carbon isotopes
near the start, and accessibleSlide5
Neutron-rich pathway through light nuclei in explosive
nucleosynthesis
sensitive
important
not included
includedSlide6
PREVIOUS WORK
Canberra data, Putt et al.
(
7Li,7Be)7Be* at 0.48 MeV
This reaction removes a proton,
adds a neutron
Should populate 3 at 0.75 MeV plus two OTHER statesapart from g.s. and 0.12 MeV
The starred peaks are the ones that contain at least in part the excited 7Be channel.The missing two peaks are the 0 and 1 from s1/2 transfer.Putt et al. identify the states as being at 0.75 and at 0.58, but we say 1.23 also possible.In the proposal, we have taken Putt et al.’s suggestion (0.58 and 0.75 peaks).like (d,p)Slide7
Reminder: this is what was shown earlier – current EXPERIMENTAL situation, with MIRROR
MIRROR
(study the
symmetry)
these levels are confused, in the compilationsSlide8
Otsuka
2012
EXPERIMENT
THREE STRONG PEAKS
AS WELL AS THE
2
(THE 0 AND 1 ARE MISSINGEXCEPT IN THE ANU RESULTS)Compare current EXPERIMENTAL situation, with THEORYSlide9
HIE-ISOLDE beam of
17
N
Reaction 17N(d,p
)
18
N5.5 MeV/A104 pps on targetT-REX plus MINIBALLGamma-ray gatingMeasure Ex and SF’s, ANC’s
THE EXPERIMENTSlide10
EXCITATION ENERGY RESOLUTION arising from the charged particle measurement
Limitations
: beam spot, strip pitch, (target thickness 0.5 mg/cm
2
)
Intensities
: using predicted cross sections and spectroscopic factors
Includes hypothetical state at neutron thresholdDeduced from measured angle and energy of protonSlide11
HOW GAMMA-RAYS WILL ALLOW THE NEAR-DEGENERATE STATES TO BE RESOLVED
Allows for Doppler correction
using crystal segment dataSlide12
40
0
(
d,p
) centre of mass angle
(
d,d
)(p,p)WHAT WE SHOULD OBSERVE WHEN WE PLOT THE T-REX ENERGY AGAINST LAB ANGLESlide13Slide14
PARTICLES
GAMMA-RAYS
THE TRIFOILSlide15
TRIFOIL DETECTOR
LPC Caen
THE TRIFOILSlide16
Angle bins: 2 degrees in
c.m
.SIMULATION OF THE DIFFERENTIAL CROSS SECTION FOR ONE OF THE NEW S-WAVE STATES
Actual predicted statistics for one week of running with 0.5 mg/cm2 targetSlide17
SUMMARY of REQUEST
We are requesting 27 shifts of
17N beam at 5.5 MeV/AWith this, we will perform (d,p) with the 17N beam, and study all populatedstates in
18N, using gamma-rays to select and identify the closely spaced levels.Of this, 21 shifts are required in order to perform the (d,p
) measurement
We believe that we can save time by not running on a carbon target
We would run on a carbon target (target contaminant) if time permitsWe have allowed 6 shifts for optimising the charge state to accelerate (to minimise contaminants) (extraction will use NO+ from nanoCaO+O2, + plasma)
and stripping methodology (what foils, and where) to eliminate 17OWe are requesting 3 shifts for setting up with a stable pilot beam, toensure that detectors and electronics are set up correctlyWe request 104 pps on the reaction target. The beam should be delivered at the T-REX + Miniball setup.We have allowed for a 5mm diameter beam spot on target (dominates the resolution)Slide18Slide19
Klupp
/
Muecher
@ Munich
Matta @ Surrey (
approx
)Reconstructed excitation energy for lowest four known states, assuming isotropic productionSlide20
220
g/cm2 CD
2 target, 275 keV FWHM resolution, 104 pps
, HELIOS at Argonne
(
Calem Hoffman, Florence INPC 2013, unpublished)