Post on 24-Feb-2016
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Present status of MINORCA installation and some ideas of possible physics cases.
Georgi Georgiev
for the local initiative groupIolanda Matea, David Verney, Guillaume Mavilla … – IPNJoa Ljungvall, Alain Goasduff, Theo Konstantinopoulos,
Stepane Cabaret, Xavier Grave … – CSNSM
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Overview High-efficiency and high-performance g-ray array – a must for any nuclear spectroscopy laboratory. What
is presently available array at ALTO? – ORGAM: 20+ coaxial Ge detectors of Euroball phase 1 – talks Iolanda Matea & Alain Goasduff
What could be achieved by combining Miniball and ORGAM arrays in Orsay – MINORCA (MINiball&ORgam Campaign at ALTO) – talk Joa Ljungvall
Few examples how MINORCA could contribute to the physics program at ALTO (Time Dependent) Recoil In Vacuum – a method that could yield high precision g-
factor results for both stable and radioactive beams How MINORCA could contribute to the following Miniball campaigns at HIE-ISOLDE? An idea for extreme g-ray spectroscopy (in the second well) – is it doable?
How far are we with the installation of MINORCA? – electronics, mechanics, DAQ
What still needs to be worked out and discussed with the user community?
What is the timing? (April 2014 Miniball @ HIE-ISOLDE?)
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Electron-nuclear spin interaction in vacuum
beam
scattered beam ion
Target recoil
(qp,fp)
g -ray emitted at angle (qg,fg)
- electron spin
- nuclear spin
)0,,()(12),( *0
,ggg qffqqq p
kqkkk
qkpkqp DQFGkW
)exp()( '',
' tCtG FFFF
FFk )10( kG
attenuation coefficients – a measure for the electron – nuclear spin interaction
gJBFFFF N
FF 2)1'(')1('
interaction frequency - depends on I and J – single frequency for J=1/2
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Time Dependent Recoil In Vacuum on H-like ions (stable beams)
beam
target
I nuclear spin(aligned)
J electron spin(random)
F = I + J
thick stopper
g-array
D=T
FF’ |g|
R.F. Horstman et al., Nucl. Phys. A248, 291 (1975)
o magnetic field for H-like ions – can be calculated from first principles!o pure H-like charge state could not be achieved
H-like ions attenuation factor
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
TDRIV – radioactive beam geometry
24Mg@120 MeV
D=T
FF’ |g|beam
target reset foil
g-array
I nuclear spin
J electron spinF = I + J
A.E. Stuchbery et al., Phys. Rev. C71, 047302 (2005).
( ( T
tdtetGTG kk
0
( ( kk GTG
( ( dtetGG tkk
particledetector
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
TDRIV @ ALTO with ORGAMORGAM array
Plastic scintilator
beam: 24Mg @120 MeV, 1.8 pnA intensitytarget: 2.4 mg/cm2 93Nb reset foil: 1.7 mg/cm2 197Au
13 HPGe @ q= 46.5, 72.1, 85.8, 94.2,
108.0,133.6, 157.6
8-fold segmented annular detector
g(2+
)
OUPS
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Experimental spectra
24Mg
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Experimental results<3% uncertainty
precise absolute distance definition
• Result consistent with previous g-factor measurement of g(2+) 24Mg TDRIV on H-like ions possible with radioactive beams
• The high granularity of Miniball could provide superior results in two ways:o Separation of the “flight” and “reset” components of the gamma line (not resolved in the present
experiment)
o More sensitive combinations for the particle-gamma correlations
v/c = 0.09180.0012B1s = 29.08019 kT q= 31.5o
g factor = 0.5280.012(%2.2)
preliminary
BIg N
L )12(
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
TDRIV on Na-like ionsN-SI-63 A.E. Stuchbery
Could a predominant frequency be observed?
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Lifetime measurements with MINORCA?• Orsay Universal Plunger System (OUPS) –
for picosecond time range Stand alone or in combination with
particle detector? segmented plastic scintillator or more
sophisticated Si detector (CD detector?)?
• Combination of high-efficient MINORCA array with a (large) number of LaBr3 detectors – simultaneous coverage of picosecond-to-nanosecond ranges
• Test of HIE-ISOLDE plunger at MINORCA?
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
g-ray spectroscopy in the second well?
Superdeformed states in the second minimum decaying through the outer barrier (EB) via fission
Island of fission isomers
- half-lives – in the nanosecond region (from few ps up to few ms)- superdeformed states – measured quadrupole moments of 236mPu (NPA
282(77) 77) and 239mPu (PRL 38(77) 387) give major axes ratio of 2:1- rotational bands observed in even-even isotopes- isomeric-to-ground state population probability (i/ g ~ 10-4) depends only on the barriers (EA, EB) and isomeric state (EII) energies, and not on the production mechanisms- isomeric g-factor measurements 237m1,m2Pu, 239mAm
Very scarce information on single-particle properties
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
A possible approach• Rotational band in the second minimum – providing
an information on (gK – gR) through branching ratios• Advantage of rotational band measurement – no
paramagnetic corrections from the implantation
• 243Cm (N=147)238U (9Be, 3n) 243Cm ~1.2 mb (gs)232Th (14C, 2n) 243Cm ? mb
• “Thick target” (~1 mg/cm2) plusparticle detection around high prompt fission rate
OR?• “Thin target” (~0.2 mg/cm2) plus recoil detection of delayed
fission in a particle-detector barrel “zero” prompt fission background
IMP, Lanzhou
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
How MINORCA could contribute to the following Miniball campaigns at HIE-ISOLDE?
• Tests with stable beams in experimental conditions similar to those @ HIE-ISOLDE, e.g. angular distributions
• Multi-step Coulomb excitation giving access to rotational bands in odd-mass nuclei (97Rb and 99Rb)
Prelim
inary
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Present status of MINORCA installation• Miniball electronics – transported to
Orsay and installed in the experimental area
• Miniball mechanical support frame – transported from Cologne to Orsay
• Combined MINORCA support design being finalized. The order for manufacturing to be finalized by end November
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
MINORCA support
beam
Miniball
ORGAMStephane Cabaret (CSNSM)Philippe Rosier (IPN)
OUPS plunger, segmented particle detector and/or other(?), readily installed in the vacuum chamber, possibility of installing a large number of LaBr3 detectors
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Data Acquisition system • Transfer of the Miniball DAQ from MBS2 to
MBS6 – in progress - Rudi Lutter (Munich)
• Combining the Miniball DAQ (“triggerless”) with the Orsay (“triggered”) DAQ – Xavier Grave et al. (CSNSM)
• To be discussed and a solution found – readout of DGF’s at high count rates (continuous) stable beams
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Ancillary (particle) detectors?• 8-fold segmented plastic scintillator – annular
detector at variable distance from the target
• CORSET – fission-products detector (mass resolution ~ 3-4)
• a CD detector – could it stand the stable-beam intensity?
• another particle detector?
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Response of the Minibal detectors to high count rate and neutron flux?• What are the count rates at which the Miniball
detectors can run safely? (bottle-neck for some physics cases)
• Control of the neutron flux per Miniball detector during measurements? (neutron detector in the array?)
• Procedure for determination of the neutron dose already observed by the detectors
• Procedure for annealing of the detectors
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Planning• MINORCA ready for experiments by April 2014
• Call for proposals at ALTO – already sent (25 Sept.); Deadline for proposals – 21 December 2013; PAC – in January 2014
• Please contact us to discuss the configurations and detectors that you need for your experiment
o Iolanda Matea (matea@ipno.in2p3.fr)
o Georgi Georgiev (georgi.georgiev@csnsm.in2p3.fr)
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Your ideas for the use
of MINORCA are
WELCOME!
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
2+ 0+
Ge_single (q = 94.2 o)
24Mg2+ 0+
24Mg
24Mg2+ 0+
Partical –Gamma Coincidence Ge4_P2
197Au5/2+ 3/2+ 511
511197Au
5/2+ 3/2+
93Nb
93Nb
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
Coulex with Miniball
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
What Miniball is?
8 triple cluster 6-fold segmented Ge tapered detectors
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
How the detectors are put together?
• High flexibility support frame that allows precise positioning of the 8 clusters at “any” angle(frame available at CERN)
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
The Coulex configuration at REX-ISOLDE
Particle detector(16 strips x 24 sectors) covering angles between Q = 17° – 54°
Vacuum chamber- 6 position targetframes- Segmented part.detector
8 triple clusters in a compact geometry around a spherical vacuum chamber
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
The transfer reaction configuration – T-REX
Position sensitive CD-like (strip) detectors in forwardand backward directions
Position sensitive (barrel, resistive layer) for anglesclose to 90°
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
What has already been done with Miniball at REX-
ISOLDE
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
What could be achieved?• High gamma-ray efficiency – possibilities of performing
“more exotic” experiments with the available (stable) beamso Orsay plunger (OUPS) o Fast timing detectors – could become available o other ancillary detectors …
• High granularity (angular definition) of Miniball – still to be explored for angular correlations
• Test bench for approaches and techniques to be used (with the same spectrometer) with radioactive beams
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
What has been done?
15+ ORGAM anti-Compton shielded Ge detectors x 0.1%
8 Miniball triple cluster detectorsat @ 14 cm from target with addbackwithout Compton shield
Efficiency at 1332 keV:6.3% - Miniball 1.8% - 15 ORGAM Ge’sTOTAL 8.1%
anti-Compton shields could be of high interest for the Miniball detectors
GEANT simulations – Joa Ljungvall
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
G. GeorgievMINIBALL Workshop and Users meeting, 24-25 Oct. 2013, CERN
What still needs to be done?• Combine the support frame of Miniball with the one of
ORGAM – on the way Stephane Cabaret (CSNSM) and Philippe Rosier (IPN)