NeAT: Neon Atom Trap
experiment for β-decay studies
B. Ohayon1 | Y. Mishnayot1,2 | H. Yishai2 | T. Hirsh2 | A. Glick1 | D. Gazit1
| I. Mukul3 | M. Hass3 | G. Ron1
1Racah
Inst. of physics | 2Soreq nuclear research center | 3Weizman
Inst. of science
𝛽-decay in the standard model
n  p  e  e
e
p

blob
n
M
g w2
e
 PCAC 
CV  1.000  CVC 
C A  1.27

5
5




u
3

1


u
1
u
4

1


v
2
Uud













2 



8  MW 
Generalizing the Weak interaction
General weak
Hamiltonian:


      C     C     
1 / 2      C     C     
       C      C    
      C     C   
H   2 1  CS e   CS' e 5 

2 
1
2
V


1
In the SM:
No T violation:
T
A
P
e
e 5 
5 
e

'
T

e

2  5 1
2 5 1

e

'
V
5 
'
A
'
P
e 
e

e
5 

Lee & Young 1956
Vector
Tensor
Axial Vector
Pseudoscalar
CV  CV' , C A  C A' , CS  CS'  CP  CP'  CT  CT'  0
All Real !
Ci  Ci'
Parity Violation:
Ci  0 and Ci'  0
C Conservation:
Ci purely real and Ci' purely imaginary .
Experimentally:
Scalar
Maximal:
CV  1.00 CVC  CA  1.27  PCAC  Im  Ci  ~ 0
Example for possible new physics
Severijns et. Al.
𝐶𝑠 ≠ 0
Search for new physics in 𝛽-decay
Total decay rate:

I  pe
pe  p
me
p
pe  p  
d 3
  1  a
 bFierz

  A
 B
D

dEe d e d 
E
E
E
I
E
E
E
E
e 
e
e

e  



Jackson, Treiman & Wyld 1957
The Beta Nu correlation coefficient:
   M F
2
C
V
SM:
SM predictions:
   Pure Fermi   1
   PureGT   1/ 3
2
C
=
2
 CS  C S
'
2

1
 M GT
3
2
C
2
A
2
2
 C A  CT  C
=
Measure 𝑎𝛽𝜈 in
18,19,23Ne with 0.1%
precision
   21Na  21Ne   0.553 2 
𝑀𝑊 2
~Acc.
𝑀𝑁𝑒𝑤
' 2
V
'
' 2
T

𝑎𝛽𝜈 from recoil ion energy dist.
1. Measure decay scheme
2. Compute recoil energy dist. for each transition,
for various 𝑎𝛽𝜈 and compare to exp.
𝒂𝜷𝝂 𝑨𝒙𝒊𝒂𝒍 − 𝑽𝒆𝒄𝒕𝒐𝒓
= −𝟏/𝟑
𝒂𝜷𝝂 (𝑻𝒆𝒏𝒔𝒐𝒓) = 𝟏/𝟑
Penning & Schmidt 1957
Carlson 1963
Recoil order corrections
for pure GT transition:
Neon scheme & isotopes
Even Ne energy Scheme:
Stable
Isotopes:
Many
Unstable
producible
isotopes:
𝟔𝟒𝟎 𝒏𝒎
𝜏~15 𝑠
𝟕𝟒 𝒏𝒎
* M. Zinner, P. Spoden, T. Kraemer, G. Birkl, and W. Ertmer (2003)
# Y. Ralchenko, A. E. Kramida, J. Reader, and N. A. S. D. Team, NIST Atomic Spectra Database (2008).
Overview of Experiment
1. Produce & filter
• SARAF I: 1mA, 5MeV
beam
• Test run: 105 23Ne/s
produced at 10uA.
• SARAF II: 40MeV, 5mA,
projected 1010 23Ne/s.
2. Excite, slow, deflect, Trap
• Cloud is cold (<1mk),
dilute and well
positioned (<1mm).
• Detect size, position
and number of atoms
optically.
• Highly isotope and
state selective .
3. Measure energy from TOF
• Add electrodes and MCPs.
• Measure recoil ions and
shake-off electrons.
• Coicidence for TOF and
background subtraction.
• Test DAQ using ionization
collisions.
Test setup with penning ionization collisions
Ionizes molecules
H2O (E+=12eV)
16.6eV
Ionizes most atoms
H2 (E+=15eV)
First signals: MOT as RGA
Ne*+H2 →
Ne*+H2O →
Balucani et. al. 2012
Hotop et. al. 1968
Cold Collisions
H2 +
22Ne+
H+
22Ne +
2
H 2 O+
NeH+
∝ (𝑇𝑖𝑚𝑒 𝑂𝑓 𝐹𝑙𝑖𝑔ℎ𝑡)2
•
Coincidence measurement of TOF distribution operational.
•
Identified hot and cold collisions as background events.
•
Investigating cold collisions for isotope effects and quantum resonances.
Summary & outlook
23Ne
produced last in SARAF
Trapping stable isotopes in Jerusalem
First 23Ne trap
coming soon!
New SARAF lab almost finished
Detection system working for
ionization collisions
Thank for listening!
Efficiencies
About 50M
events for
0.1%
precision
Event Rate
140/s
Trapping
Efficiency
Throughput
(Ne23/s)
Acquisition
time (~100Hr)
Ion collection
(~100%) and
detection (~50%)
Recycling?
Source
~10-5
LN,
mixing
~10-4
Cooling
and
trapping
(10-5)
Collimations
~10-3
Metastable
effective
lifetime (40%)
Throughput=107
Needed efficiency=10-5
Throughput=109
Needed efficiency=10-7
Testing Electrodes and Data acquisition
(and systematics)
High background
Ne*
H2O
Ne*
Ne*
Penning
e
Low background
High loading rate
H2O+
Penning
Ne
e
e
Brunneti 2013
Ne+
Ne
Associative
2Ne+
Temperature
Collisions
Cold
Hot
•
•
Centrifugal force creates potential
barrier that keeps reactants
separated. However, reactions
may still proceed through
tunneling.
Reaction rates and pathways are
governed by quantum
mechanical effects or long range
interactions.
Ultracold
Chemical bonds
Interatomic separation
De Broglie wavelength (nm)
Weiner 1999
Recoil TOF detection
E0
Ion
Electron
MCP
MCP
Detector
Daughter
Father
Nucleus
Nucleus
Detector
RGA signal
Conversion of rokinetic
All under 1eV,
Ne2 useful for cal
ge iMCP
rode -
Planned Ionization setup Model
Simulation
•
Low Voltage
eMCP input
electrode
Voltages
•
•
•
Sim
Mo
Low