Transcript Lecture 1 ppt - High Energy Physics

Neutrino mass, Double beta
decay, Low background, Low
energy, deep underground exexperimental partical physics.
Dr. Vladimir Vasiliev
UCL Physics building C14,
vv [at] hep.ucl.ac.uk
www.hep.ycl.ac.uk/~vv/lectures
Double beta decay primer
Neutrino, the story
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Proposed by W. Pauli in 1930
Reactor ne observed,1953
ne≠ nm, 1960-64
Electro-weak theory GWS
Neutral current discovered, 1973
Z, W observed at LEP, 1983
Z width ⇒ 3 n families
nt,
SM almost complete.
Double beta decay primer
Neutrino oscillations.
Electro- weak flavourbasis is rotatedrelativeto massivestates:
n   U i n i
n i are eigenst ates of translation operator:
ˆ
Tˆ (x,t)  e i(pˆ x -Et) , Tˆ (x,t)n i   n i
but n  are not,hence:
n  Tˆ (x,t)n   0 for   
 probability toobserven  in n  beam.
T wo flavourscase :
(m22  m12 ) L
 1  P (n e  n e )
P (n e  n m )  sin 212 sin
4E
2
2
Double beta decay primer
Absolute neutrino mass
How to weight a particle?
• resonance in cross section
• decay kinematics
NO
YES!
• Cosmology, gravitation
YES!
• double beta decay
YES!
Double beta decay primer
Kinematical experiments
Double beta decay primer
Kinematical experiments
Challenges:
• Small rate at the tail  low Q
• Energy resolution ~ mn  non-traditional detectors
• Effect is at the scale of atomic energy (H line 13.6 eV)
 enormous effort to control systematic error
• 3H 18 keV -decay (Troitsk, Maiz, Katrin)  Use of
MAC-E filter
• 187Re 2.47 keV -decay (MARE)  Use of cryogenic
bolometer (see CUORE experiment for bolometer
detector)
Double beta decay primer
Kinematical experiments
Magnetic Adiabatic Collimation + Electrostatic Filter
• Two superconducting
solenoids make a guiding
magnetic field
• Electron source in left solenoid
• Electrons emitted in forward
direction are magnetically
guided
• Adiabatic transformation:
 Parallel beam at
analyzing plane
Double beta decay primer
Kinematical experiments
Mainz result
Current best limit mn < 2.2 eV
Double beta decay primer
Kinematical experiments
KATRIN
DE = E×Bmin/Bmax = 0.93 eV
Double beta decay primer
Cosmology
galaxy formation movie
millennium simulations
http://www.mpa-garching.mpg.de/galform/virgo/millennium/
Double beta decay primer
Cosmology
Double beta decay primer
Cosmology
Double beta decay primer
http://video.google.com/videoplay?docid=-8252705102362324792&q=sdss
Cosmology
http://space.mit.edu/home/tegmark/cmb/movies.html
Double beta decay primer
Cosmology
GALAXIES
CMB
Double beta decay primer
Cosmology
Key problems: what data to use? what are the systematic errors in the data?
Ex.: SELJAK, SLOSAR & MCDONALD (ASTRO-PH/0604335) FIND
 mn  0.17 eV @ 95%
SELJAK, SLOSAR & MCDONALD
SDSS LYMAN-ALPHA
WMAP-3 NORMALIZATION
Double beta decay primer
Cosmology
Key problems: what data to use? what are the systematic errors in the data?
Ex.: Degeneracy between dark energy state equation and neutrino mass
STH, ASTRO-PH/0505551 (PRL)
DE LA MACORRA ET AL. ASTRO-PH/0608351
Double beta decay primer
DE LA MACORRA ET AL. ASTRO-PH/0608351
Absolute neutrino mass
Double beta decay primer
DE LA MACORRA ET AL. ASTRO-PH/0608351
Dirac neutrino
Dirace qu ationfor e le ctron :s

(i m
 m )  0;
xm
1
( (i m  m )  mD2  )  h.c.
2
it i s con vin ie nto
t work with R an d L proje ction
s:
1
1
 R, L  (1   5 )  PR , L ; PR, L  (1   5 )
2
2
  R L;
L
 R R   L L  0
1
LMD   mD2 ( L R   R L )
2
e le ctroni s ch arge d,th u sn o oth e rm asste rm sallowe d.
Applyin gth esam efor n e u trin o,
on ecom e sto Dirac
n e u trin ode scriptio
n . In S Mn R doe sn t' e xist,h e n ce
mn  0!
Double beta decay primer
Charge conjugation and bar
Bar ope rator:
  ( ) 0
*T
C h argecoju gation:
 C  C  T  i  0 2 
( R) C  ( C ) L ;
Double beta decay primer
T
Majorana neutrino
n is n e u tral   C an d C te rm sare allowe d( C  CC-1 )

1 2
2
mML ( L ( C ) R  ( C ) R L )  mMR
( R ( C ) L  ( C ) L R )
2
in trodu ce:n 1  n L  (n C ) R ; n 2  n R  (n C ) L
LMM  
n 1, 2 C


1 2
2
mMLn 1n 1  mMR
n 2n 2
2
 n 1, 2  particle an ti- particle
LMM  
Majoran ade scriptio
n assu m e s2 - com pon e n n
t e u trin o.
In caseof mn  0, se con don eis ste rilein S M, th u s
Diracan d Majoran ade scriptio
n s are ide n tical
Double beta decay primer

See-Saw
In ge n e ralcase:
LM  LDM  LM
M
LM

1
  vL
2
LM  
v
C
L

 mML

 mD
mD  v C R 


mMR  v R 
1
( m1 v1v1  m2 v2 v2 )
2
mMR  mML
( mMR  mML ) 2
m1, 2 

 mD2
2
4
i f mMR  mD , mML :
mD2
m1  mMR ; m2 
mMR
Th i s can e xpl ai nsm al n e ss
of mn
Double beta decay primer
Leptogenesis
 Generate DL in out of equilibrium decay of heavy
Majorana neutrinos
 Convert DL → DB
 Leptogenesis is consistent with
neutrino masses and cosmology
 Leptogenesis is predictive
Double beta decay primer
Neutrinoless  decay
If ne utrinoare massiveandMajoranaparticle s,
due to m 2  RC L te rmin Lagrangianonecan
obse rve2 0n
Golden plated channel:
~<m>2/E2
(A,Z)→(Z+2,A)+2eDouble beta decay primer
a) 2 electrons
b) E1+ E2Q
Double beta (2n) decay
(A,Z)→(Z+2,A)+2e-+2ne
allowed in Standard Model
very rare, ~GF4
typical T1/2=1018-1021 years
First indirect confirmation for 82Se,
130Te by geochemical analysis
First direct observation: TPC with 82Se
foil, 32 events.
Elliott SR Hahn AA and Moe MK, 1987
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Double beta () decay
1935 by Carl von Weizsäcker
(A,Z)→(Z+2,A)+2e-+2ne
(A,Z)→(Z-2,A)+2e++2ne
(A,Z)→(Z+2,A)++e++2ne (EC)
(A,Z)→(Z+2,A)+2+2ne (ECEC)
~ 69 stable and 28 -unstable  isotopes
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Double beta (0n) decay, experimental signatures
(A,Z)→(Z+2,A)+2e-
Experimental signatures:
• two e- from same place at the
same time
• daughter (Z+2,A) nuclei
appears
• the sum of e- kinetic energy
equals to Q
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Big questions
 What are the absolute masses?
 Direct mass measurement, Cosmology, 0n
 What is the mass ordering, 123 or 312?
 Long baseline oscillations, 0n
 Are v's Dirac or Majorana Particles
 0n
0n is the key experiment for neutrino physics
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Home problems & questions
1) Usi n gslide19, prove th efollowin g:
 L   PR
PR  PR ; PL  PL
2
2
3) Why tritium is the isotope of
choice for kinematical experiments?
4) What if dark matter sector has other
light particles similar to neutrinos (in
terms of mass and interaction cross
section). What would happen with
neutrino cosmological mass
boundaries?
 L R  R L  
( R ) C  ( C ) L
n 1, 2 C  n 1, 2
v1v1  vL v C R  v C R vL
2) derive m1,2 for the slide 21
5) Why not to search double beta
decay of beta-unstable isotopes?
6) What do you know about Occam's
razor? How one can apply it to argue
against simple extension of SM with
massive Dirac neutrinos?
Double beta decay primer