1 Nondestructive Measurement Nondestructive Measurement of Charged Particles of Charged Particles Kensuke Homma / Kazuhiro Hosokawa Hiroshima University 1. A novel principle of charged particle sensing 2. Verification of the detection principle in a static condition 3 . Future prospects
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1 Nondestructive Measurement of Charged Particles Kensuke Homma / Kazuhiro Hosokawa Hiroshima University 1. A novel principle of charged particle sensing.
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Kensuke Homma / Kazuhiro HosokawaHiroshima University
1. A novel principle of charged particle sensing2. Verification of the detection principle in a static condition3 . Future prospects
2
Principle of charged particle detectionPrinciple of charged particle detection
Conventional principle developed so farutilizes local inelastic processes such as ionizations and excitations with the typical energy loss above 1eV.
Can we use a quasi elastic process such as macroscopic polarizations with an extremely small energy loss?It opens up a novel charged particle sensing without changing velocities of charged particles.
Is the macroscopic polarization detectable by visible rays? Crystals with the Electro-Optical property combined with the laser readout are suitable for the purpose.
3
Novel principleNovel principle
2204 Rn
eET
R
t
n
Rt
n
cl
e-
Measure instantaneous variation of refractive indexin Electro-Optical crystal by external electric fields.
e-
z
z
xy
y
x
R
x
))5.0(tan(cos 3/11 Ry
TEO Erfn )(
R
e
n
rfln EO
302
)(2
R
Phase retardation
4
How to extract small phase retardation ?How to extract small phase retardation ?
d f
Lens
(x0,y0)
y
zx
(x1,y1) (x2,y2)
Fraunhoffer diffraction at an infinite distance can be obtainedby lens at a short distance.
The diffraction pattern at a focal pointat a focal point corresponds toFourier transformation of input shape of a refractive media.
)},({)(|),(| 00222
22 yxFfyx
5
Diffraction patterns with a thin wire of 50Diffraction patterns with a thin wire of 50mm
Horizontal wire Tilted wire Vertical wire
Pictures taken by wide dynamic range CMOS camera
No wire
Fourier transformation of Gaussian is Gaussian with smaller waist.
Narrowing the wire width makes diffraction pattern extend more outside.
Diffraction pattern keeps vector information on the projection.
Gaussianprofile
6
Verification with LiNbOVerification with LiNbO3 3 in quasi static statein quasi static state
• Electron current: ~1nA• Electron beam diameter: ~50m(FWHM)• Electron kinetic energy: 4keV• Electron beam distance: ~300m• Laser intensity: 1W• Laser wave length: 532nm• Focal length of lens: 10cm• CMOS camera dynamic range: 103dB• CMOS camera exposure time: 20sec• CMOS camera pixel size: 45 x 45 m2 y [m]
Expected # of photons along y-axis
~10-10
E1=E2=0, r13=8.7 pm/V
Sampling here
Index ellipsoid of LiNbO3 crystal
Local phaseretardation
z
xy
E3 e-
7
Experimental setupExperimental setup
Wide dynamic rangeCMOS camera
CW Laser injection
Plastic Scintillater+ PMT for e- monitor
凸 Lens
Flexible opticalfiber bundle
DC e- gun
Coupling toOptical fiber bundle
LiNbO3
crystal
Location of fiber bundle Auto stage+y
+x
8
Shot by shot intensity profiles at focal planeShot by shot intensity profiles at focal plane
Large electro-optical coefficient Fast rise and not too long duration timecompared to effective impact time
KH2PO4(KDP)
KD2PO4(DKDP)
KH2PO4(KDP)
T=14.2K
T=4.2K
T=1.3K
LiNbO3
10
Expected diffraction pattern by single electronExpected diffraction pattern by single electron
Developed eclipseflexible fiber bundle
Mask here
11
SummarySummary
• The novel remote sensing technique with laser diffraction readout was qualitatively verified at a static condition.
• In ideal case, even remote sensing of non-relativistic single electron is possible with cooled DKDP crystal and the test experiment is on going.
• If single charged particle is detectable, it would open up many applications like; end-point determination in beta decays with the nondestructive ToF measurement, mass spectroscopy of ionized protein beam and so on.
12
Backup slides
13
x
y
z
= 1mm
=
0.1
mm
Diffraction with square apertureDiffraction with square aperture
Merits at a focal point:1. S/N can be greatly improved compared to conventional interferometry2. Incident photon intensity can be lowered3. Size can be extremely compact4. Pattern is simple compared to grating optics
2222
2
2
2
2
2
2 2,
2)sin()sin(y
fx
fI yx
x
x
x
x
14
One more stepOne more step
x
y
e-
DKDP crystal
Profile of scanning laser
Linear polarizationz
e-
y
z x
Scanning laser
y’ x’
z
zo
zozo
EO
e
z
o
z
o
z
eoo
ErnErnErn
rf
zn
yErn
xErn
xyErzn
yn
xn
633
632
632
22
2632
2632
632
22
22
2
/1
1
/1
1)(
1'1
'1
'1
12111
15
Ultimate goal of this studyUltimate goal of this study
Eend
Cou
nt r
ate
me me
Big issue in particle physicsAbsolute scale of neutrino mass
Big issue in cosmologyAre there relic neutrinos?Lepton number asymmetry btw. and ?
Can we achieve energy resolution beyond 1eV limit by a novel method ?
Eend
Cou
nt r
ate
me<< 1eV
Kinetic energy measurement of beta decay is a key measurement
p
n e-
en
e-
e
p
eepn 3 body decay
epne2 body interaction
2 bodyNeutrino temperature 10-4 eV
Electron kinetic energy
)( enpe
3 body3 body
16
Spectrometer for end-point measurementSpectrometer for end-point measurement
LOI of KATRIN experiment (hep-ex/0109033)
)1(10~10
1
||/||
54
max
min
0
max
min000
eVB
B
E
E
B
BeUEeU
BET
under adiabatic field change
Phase space in the last 1eVjust below E0 is 2x10-13
10-4 eV resolution to 10eV electronwith 10m ToF section may be achievable.
18
R
vt
dr
rd(tan)
r
v
d
Energy loss per single elementEnergy loss strongly depends on R:
If R is small,phonon excitations cause typically meV order energy loss
If R is large,polarization variation may be caused by notaccompanying phonon excitations due to structural phase transition of DKDP crystal. In such a case, energy loss would be expressed as