Download MATS Collaboration - Indico - Variable Energy Cyclotron Centre

MATS Collaboration
Precision Measurements of very short-lived nuclei using an
Advanced Trapping System for highly charged ions
Belgium, Canada, France, Finland, Germany, India, Russia, Spain, Sweden, USA
10 countries; 24 Institutes; 87 Members
Present Spokesperson: D. Rodriguez
STATUS
MATS Technical Design Report Submitted and received very high grades
from NuSTAR Referees.
Paper Published:
1) D. Rodriguez, K. Blaum, A. Ray, P. Das et al., European Physical Journal,
Special Topics, 183, 1 (2010).
Indian Proposal
(Already Accepted)
Q-value measurements of very short-lived beta emitter
from the measurement of the energy of recoiled nucleus
Members of Indian Collaboration
(MATS)
A. Ray, P. Das, A. Sikdar, M. Ahmed, S. Saha, S. Murali
Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata – 700064
A. Goswami
Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata – 700064
A. De
Raniganj Girls’ College, Raniganj, Bardhaman, West Bengal
Physics Goals of Indian Collaboration
High Precision Q-value measurement of short-lived beta decays.
(Already accepted by International Collaboration; part of MATS TDR).
Motivation for High Precision Q-value Measurements
Test of Conserved Vector Current (CVC) and unitarity of
Cabibbo-Kobayashi-Maskawa (CKM) matrix elements.
According to CVC for superallowed Fermi transitions
Ft  ft (1   R )(1   c ) 
K
2GV2 (1   R )
 R  Nucleus - dependent radiative correction
 c  Isospin symmetry breaking correction
 R  Nucleus independen t radiative correction
G V  Vector coupling cosntant
Ft independent of nuclear structure. Tested for many nuclei.
CKM matrix
A quark of one flavor can change into a quark of another flavor differing
by one electronic charge through beta decay.
 d   Vud
  
 s    Vcd
 b   V
   td
Vus Vub  d 
 
Vcs Vcb  s 
Vts Vtb  b 
 d 
 
 s   Weak Eigenstates
 b 
 
Violation of unitarity reported
Physics beyond standard model?
d 
 
 s   Mass eigenstates
b
 
Unitarity Matrix
2
2
2
Vud  Vus  Vub  1
Determination of Vud
2
G
Vud2  V2 ; GV  Vector coupling costant
G
G  Fermi Coupling constant for muon decay
GV obtained from Ft
Ft obtained from ft
ft depends on the fifth power of Q-value.
Very Important to measure Q-value with high precision to determine
Vector coupling constant.
Usual method: Determination of Q-value from the high precision mass
measurements of parent and daughter nuclei.
Difference of two large numbers.
Our Proposal
We propose to directly measure Q-value from the recoil energy
of the daughter nucleus using Penning trap system.
Avoids subtraction of two large numbers.
In the case of very short-lived nuclei (t< 50 ms), high precision
mass measurement is not generally possible.
Our proposed method should achieve reasonably high precision
even for very short-lived parent nuclei.
Penning trap
Radial confinement by a strong homogeneous magnetic field
 Axial trapping by a weak static quadrapolar electric potential
Motion of an ion is the superposition of three characteristic
harmonic motions:
f+  f-  fc
– axial motion (frequency fz)
– magnetron motion (frequency f–)
– modified cyclotron motion (frequency f+)
Decay Studies
Q-value Measurements using a Penning trap system.
Short-lived parent nucleus (half-life 50 ms or less) not a limitation
Daughter has to be relatively long-lived (half-life  10 s)
Q-value should be relatively high >5 MeV for a high accuracy measurement.
Recoiled daughter nucleus should enter measurement trap axially through
a small axial hole (< 100 micron).
Single ion measurement
19 Electrode TRAP Assembly
50.00 mm
57.80 mm
20.00 mm
14.00 mm
0.10 mm
132.20 mm
Electrode
Number
Applied
Voltages
1
2 3
4
5
6
7 8 9
10 11 12 13 14 15 16 17 18 19
50 50 33 8.5 0.0 8.5 33 50 50
50 200 200 132 40 -20 40 132 200 200
250
200
150
100
50
0
0
20
40
60
80
100
120
200
9.0
180
8.0
160
7.0
140
6.0
120
5.0
100
4.0
80
3.0
60
40
2.0
20
1.0
0
0.0
140
0
20
40
60
80
Along TRAP axis (mm)
100
120
Time of flight (  s )
Kinectic Energy (eV)
Simulation Result for Ion of mass 100 amu recoiling with with 180 eV
Determination of the energy of recoiled nucleus
Trap recoiled nucleus without changing its energy
Use beta particle as trigger.
Lower trap entrance potential before ion enters.
Then raise after ion has crossed half-way.
Simulation result:
Result: Raising entry side potential of electrode #10 from say 50 V to 100V
Change of potential profile at the other half 1 part in 105. Better correction
possible.
Possible to trap without changing energy.
Set narrow window (0.1 eV) on entrance side so that
the nucleus is just trapped. This determines energy
of recoiled nucleus within 0.1 eV and identifies nucleus.
There is a distribution of energy of the ions.
Measure high energy part of the spectrum in fine bins.
Use beta particle or suitable gamma ray trigger for
timing and normalization purpose.
Since the ion is trapped, we get its energy by knowing
the limiting situation when it is trapped.
After trapping the ion, the nucleus can be identified
by measuring its mass.
Detection of ion in trap
Axial oscillation frequency of ion
z 
qVdc
md 2
Mass dependent oscillation frequency can be used for detection without ion loss.
Voltage induced by an oscillating ion (MHz frequency) in the ring electrode picked up,
Amplified by an amplifier operating at liquid helium temperature and then by
room temperature amplifier.
Fourier transform of the signal gives axial frequency and cyclotron frequency.
Mass identified.
Outlook
Simulation work has shown the possibility of trapping recoiled daughter nucleus
without changing its energy.
GSI and University of Mainz groups has agreed to provide us with
Superconducting magnet and cryostat facility and other
Infrastructural support.
We are expected to provide
Required traps, electronics and control system.
VECC Cryogenic Penning Trap
A cryogenic Penning trap system under construction at VECC
Magnet Cryostat commissioned.
5-electrode Penning trap and hanging assembly under construction.
Commissioning of magnet-Cryostat System
Magnet-cryostat will house Penning trap.
Magnet cryostat cooled to 4K and powered up by using a detachable charger wand.
Main solenoid coil current = 96.9 Amp corresponding to magnetic field =5 Tesla achieved.
Both main coil and shim coils put in persistent mode. Power cables disconnected and external
power supply switched off.
Measurements after 18 hours showed exactly same main coil and shim coil currents.
Magnet commissioned in persistent mode.
VECC Penning trap to be used for testing Q-value measurement idea.
Plan to measure relativistic electron mass from beta spectrum.
Obtain kinetic energy of relativistic electron.
Could be useful for measuring end-point energy of beta decay spectrum.
Summary
VECC proposal already accepted by MATS collaboration and NUSTAR
VECC cryogenic Penning trap project progressing well.
Our MATS program complementary to our work at VECC
High precision measurement of beta spectrum near end-point
Trap electrons emitted from a beta emitter in a Penning trap.
Energy too high for trapping!
Possible to trap those electrons emitted almost perpendicular to the magnetic field
with small axial energy.
Measure relativistic mass of the electron. Relativistic mass carries information
about the kinetic energy of the electron.
Determination of the kinetic energy of electron from the measurement of
Cyclotron frequency.
In principle, very high accuracy possible.
Electrostatic potential
Vdc  2 1 2 
 ( Z , r )  2  z  r  where
2 
2d 
2

r
1
d 2   z0 2  0 
2 
2 
2r0 and 2 z0 are the inner ring diameter and distance between
end electrodes .
Costs
FAIR Cost Book Costs
Cost per trap = 20,000 Euro
Total cost for 2 traps = 40000 Euro =Rs 28 lakhs
Cryogenic Electronics cost = 70,000 Euro = Rs 49.0 lakhs
Cost of High precision power supplies ( 2 Nos) with custom made
control = 45000 Euro
= Rs 31.5 lakhs
Cost of Data Acquisition System = 12000 Euro = Rs Rs 8.4 lakhs
Total cost (FAIR Book) = Rs 116.9 lakhs
Travel Cost : 20% of FAIR Book cost
Total Cost: Rs 140.28 lakhs
The amount will be spent over a period of 5 years.
Responsibilities and Obligations of MATS Collaboration Groups
Contribution
Theory
Simulation Studies
Atomic-Mass Evaluation
Control System
Beamlines
Beamline Detectors
Vacuum System
RFQ Buncher + Switchyard
EBIT
Q/A Separation
Off-Line Ion Source
Preparation Trap
Measurement Trap
Electronics
TOF Detector
FT-ICR Detector
In-Trap EC Detector
PhD / years
PostDoc / years
Engineer / years
UPS UGW UEN
X
X
X
X
X
X
X
X
X
GSI
UMZ
X
UG
UJ
Institutes
LLNL LMU
X
3
SU TRIUMF VECC
X
X
X
X
X
X
X
6
1
2
MSU
X
X
X
X
X
X
3
2
1
ULB
X
X
X
X
X
X
HD
3
3
X
X
X
X
X
X
X
X
X
X
8
4
2
X
X
X
X
X
X
2
1
X
X
2
4
2
1
2
1
0,5
1,5
2
Difficulties of the measurement
1) Electron loses its energy due to synchroton radition.
Synchroton emission can be inhibited in the Penning trap cavity, if the
Synchroton frequency lies outside the line-width of the cavity frequency.
2) Presence of large number of electrons in the trap.
Measure synchroton radiation frequency or induced image current on
Trap electrodes within a millisecond with 1 part in a million accuracy.
Simulation work going on to check feasibility.
Our Responsibilities
1) Decay Trap
2) Measurement Trap
3) Associated Electronics
Simulations of the traps. (Already started)
Final Design of the traps
Fabrication of the traps
Testing of the traps
Installation of the traps at MATS
Participation in Experiment, Data Analysis, Paper writing etc.
VECC Penning trap Project
A Penning trap Project going on at VECC.
Magnet-cryostat cooled to 4K.
Cryogenic insert tested.
A prototype Penning trap already fabricated at VECC Workshop.
Final drawing and design going on.
Our MATS program would be complementary to our VECC program.
Technical Challenges
Construction of cylindrical Penning traps
Mechanical finish within 10 microns.
Alignment within 10 microns.
High precision power supply , hardware controlled.
A few microsecond after the trigger signal from beta particle,
Voltage to change by 0.1V-0.3V within 200 -300 ns.
Hardware control required.
Low temperature ( 4K) electronics.
Radio frequency amplifier
LC circuits
Ion position along trap axis
(mm)
140
120
100
80
60
40
20
0
0.0
2.0
4.0
6.0
8.0
10.0 12.0 14.0 16.0 18.0 20.0
Time of flight ( )
Double trap
electrode
Assembly
ION
SOURCE
Planned VECC TRAP
MATS
Precision Mass measurement
TOF
Ion production
FRS Low
Energy Branch
c
RFQ
EBIT
Mass Analyzer
Preparation
Penning trap
Beam bunching
Charge breeding
q / A - selection
Cooling process
Q
Precision
Penning trap
Time-of-flight
detector
Mass measurement
Detection