Present status of MINORCA installation and some ideas of possible physics cases.
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Transcript of Present status of MINORCA installation and some ideas of possible physics cases.
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 ([email protected])
o Georgi Georgiev ([email protected])
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)