SLIDE 1
Thanks
- Thanks to the organizers for the invitation to speak
Philippe Martel - Meson A2 1/26
2 Thanks Thanks to the organizers for the invitation to speak - - PowerPoint PPT Presentation
2 Thanks Thanks to the organizers for the invitation to speak - - PowerPoint PPT Presentation
Meson Investigations by the MAMI A2 Collaboration 15th International Workshop on Meson Physics Philippe Martel Krakow, Poland - 12 June 2017 Institute for Nuclear Physics Johannes Gutenberg University of Mainz A 2 Thanks Thanks to the
SLIDE 2
SLIDE 3
Thanks
- Thanks to the organizers for the invitation to speak
- Thanks to all of you for still being here (perhaps to the rain for
‘encouraging’ you all to come to the last day)
Philippe Martel - Meson A2 1/26
SLIDE 4
Thanks
- Thanks to the organizers for the invitation to speak
- Thanks to all of you for still being here (perhaps to the rain for
‘encouraging’ you all to come to the last day)
- Since we’re here, let’s talk about some meson physics at MAMI
Philippe Martel - Meson A2 1/26
SLIDE 5
Outline
- 1. What should we do
- 2. What can we do
- 3. What have we done
- 4. What are we doing
Philippe Martel - Meson A2 2/26
SLIDE 6
What should we do
SLIDE 7
Should we study mesons?
- We’ve had four days of talks regarding this...
Philippe Martel - Meson A2 - What should we do 3/26
SLIDE 8
Should we study mesons?
- We’ve had four days of talks regarding this...
- If you are not already convinced, I’m not going to change your mind
Philippe Martel - Meson A2 - What should we do 3/26
SLIDE 9
Should we study mesons?
- We’ve had four days of talks regarding this...
- If you are not already convinced, I’m not going to change your mind
- Preferred stance of experimentalists: “Just let me go measure things.”
Philippe Martel - Meson A2 - What should we do 3/26
SLIDE 10
Should we study mesons?
- We’ve had four days of talks regarding this...
- If you are not already convinced, I’m not going to change your mind
- Preferred stance of experimentalists: “Just let me go measure things.”
- Of course it’s always nice if your work is beneficial, so what would the
theorists like to have...
Philippe Martel - Meson A2 - What should we do 3/26
SLIDE 11
Observables
Beam Target Recoil x y z x′ y′ z′ Unpolarized σ T P Linear Σ H P G Ox′ T Oz′ Circular F E Cx′ Cz′ Beam Target/Recoil x y z x′ y′ z′ x′ y′ z′ x′ y′ z′ Unpolarized Tx′ Tz′ Σ Lx′ Lz′ Linear Lz′ E Lx′ Cz′ σ Cx′ Tz′ F Tx′ Circular G Oz′ Ox′ H
Philippe Martel - Meson A2 - What should we do 4/26
SLIDE 12
Observables
Beam Target Recoil Both x y z x x′ z′ x′ z′ Unpolarized σ T Tx′ Tz′ Linear Σ H P G Ox′ Oz′ Lz′ Lx′ Circular F E Cx′ Cz′ As L. Tiator described:
- 16 total observables
- 8 observables without recoil polarization
- 8 observables without target polarization
- Do not need all 16 to have complete picture
Philippe Martel - Meson A2 - What should we do 4/26
SLIDE 13
What can we do
SLIDE 14
Mainz Microtron (MAMI) e− Beam
- Injector → 3.5 MeV
- RTM1 → 14.9 MeV
- RTM2 → 180 MeV
- RTM3 → 883 MeV
- HDSM → 1.6 GeV
Philippe Martel - Meson A2 - What can we do 5/26
SLIDE 15
Polarized Photon Beam
A high energy electron can produce Bremsstrahlung (‘braking radiation’) photons when slowed down by a material.
- Longitudinally polarized electron
beam produces circularly polarized photon beam (helicity transfer)
- Pe measured with a Mott
polarimeter before the RTMs.
- Circular beam helicity flipped by
alternating the e− beam polarization (≈ 1 Hz).
(MeV)
γ
E 50 100 150 200 250 300 350 400 450
e
/P
γ
P 0.2 0.4 0.6 0.8 1
Pγ = Pe 4EγEe − E 2
γ
4E 2
e − 4EγEe + 3E 2 γ
Philippe Martel - Meson A2 - What can we do 6/26
SLIDE 16
Polarized Photon Beam
A high energy electron can produce Bremsstrahlung (‘braking radiation’) photons when slowed down by a material.
- Diamond radiator produces
linearly polarized photon beam (coherent Bremsstrahlung)
- Polarization determined by fitting
the Bremsstrahlung distribution.
- Linear beam orientation typically
flipped every two hours.
energy [MeV] γ Incident 100 150 200 250 300 350 400 450 500 550 600 Normalised Enhancement 1 1.5 2 2.5 3
Philippe Martel - Meson A2 - What can we do 6/26
SLIDE 17
Photon Tagging
- e− beam with energy E0,
strikes radiator producing Bremsstrahlung photon beam with energy distribution from 0 to E0.
- Residual e− paths are
bent in a spectrometer magnet.
- With proper magnetic
field, array of detectors determines the e− energy, and ‘tags’ the photon energy by energy conservation.
Philippe Martel - Meson A2 - What can we do 7/26
SLIDE 18
Targets
Polarized frozen spin butanol target
- Dynamic Nuclear Polarization (DNP)
- Butanol (C4H9OH) for polarized protons
- r D-Butanol (C4D9OD) for polarized
deuterons
- Pmax
T
> 90%, τ > 1000 h Unpolarized targets
- LH2/LD2
- 4He
- Solid targets (C, Al, Pb, etc.)
Philippe Martel - Meson A2 - What can we do 8/26
SLIDE 19
Detectors
CB NaI PID MWPC Target TAPS BaF2 PbWO4
Crystal Ball (CB)
- 672 NaI Crystals
- 24 Particle Identification
Detector (PID) Paddles
- 2 Multiwire Proportional
Chambers (MWPCs) Two Arms Photon Spectrometer (TAPS)
- 366 BaF2 and 72 PbWO4
Crystals
- 384 Veto Paddles
Philippe Martel - Meson A2 - What can we do 9/26
SLIDE 20
What have we done
SLIDE 21
Busy Two Years
- Since Meson2016, we’ve been quite productive...
Philippe Martel - Meson A2 - What have we done 10/26
SLIDE 22
Busy Two Years
- Since Meson2016, we’ve been quite productive...
- Taken
- 3 weeks polarized target data
- 6 weeks recoil polarimeter data
- 6 weeks 4He target data
- 3 weeks LD2 data
- 16 weeks LH2 data
- 2 weeks of tests
- Total = 36 weeks (feels like more)
Philippe Martel - Meson A2 - What have we done 10/26
SLIDE 23
Busy Two Years
- Since Meson2016, we’ve been quite productive...
- Taken
- 3 weeks polarized target data
- 6 weeks recoil polarimeter data
- 6 weeks 4He target data
- 3 weeks LD2 data
- 16 weeks LH2 data
- 2 weeks of tests
- Total = 36 weeks (feels like more)
- 1 EPJA, 1 PRL, 1 PLB, and 5 PRCs published
- 1 PRC and 1 PRD accepted
- 1 PLB submitted
Philippe Martel - Meson A2 - What have we done 10/26
SLIDE 24
Σ - γp → π0p [S. Gardner, EPJA 52, 333 (2016)]
Well that’s a lot of data.
Philippe Martel - Meson A2 - What have we done 11/26
SLIDE 25
Σ - γp → π0p [S. Gardner, EPJA 52, 333 (2016)]
That’s a little bit better.
Philippe Martel - Meson A2 - What have we done 11/26
SLIDE 26
Σ - γp → π0p [S. Gardner, EPJA 52, 333 (2016)]
ˇ Σ(W , θ) = σ0(W , θ)Σ(W , θ) = q
k 2lmax
- n=2
aΣ
n (W )P2 n(cosθ)
2
Philippe Martel - Meson A2 - What have we done 11/26
SLIDE 27
γp → ηp/γp → η′p [V. Kashevarov, PRL 118, 212001 (2017)]
0.1 0.2 0.1 0.2 0.3
- 1
- 0.5
0.5 1 -1
- 0.5
0.5 1 W=1888 MeV W=1888 MeV
dσ/dΩ [μb/sr]
W=1888 MeV W=1888 MeV W=1938 MeV W=1938 MeV W=1956 MeV W=1956 MeV
cosΘη
*
(a) (b) (c) (d)
0.02 0.04 0.06 0.08 0.02 0.04 0.06 0.08
- 1
- 0.5
0.5 1 W=1925 MeV W=1925 MeV
dσ/dΩ [μb/sr]
W=1938 MeV W=1938 MeV W=1944 MeV W=1944 MeV W=1956 MeV W=1956 MeV
cosθη′
- 1
- 0.5
0.5 1
Present A2 data in magenta, previous in blue, CLAS [M. Williams et al., PRC 80, 045213 (2009)] in black crosses, CBELSA/TAPS [V. Crede et al., PRC 80 055202 (2009)] in open circles
Philippe Martel - Meson A2 - What have we done 12/26
SLIDE 28
γp → ηp/γp → η′p [V. Kashevarov, PRL 118, 212001 (2017)]
1 2 3 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05
W [GeV] σ [μb]
Run I Run II Run III CBELSA/TAPS-09 0.5 1 1.5 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Run III CBELSA/TAPS-09 SAPHIR-98 ABBHHM-68 AHHM-76
W [GeV] σ [µb]
Present A2 data in magenta, CBELSA/TAPS [V. Crede et al., PRC 80 055202 (2009)] in open circles, with ηMAID-2003 [Nucl. Phys. A700, 429 (2002)] (black dotted), SAID-GE09 [Phys. Rev. C 82, 035208 (2010)] (blue), BG2014- 2 [EPJA 47, 153 (2011); EPJA 48, 15 (2012)] (magenta)
Philippe Martel - Meson A2 - What have we done 12/26
SLIDE 29
π0 → e+e−γ [S. Prakov, PRC 95, 025202 (2017)]
Transition Form Factors (see talk by L. Heijkenskjoeld in Parallel Session B4)
- Pion-exchange term aπ0
µ in HLbL scattering
- Decay width of π0 → e+e−
]
2
[GeV/c
- e
+
e
m
0.02 0.04 0.06 0.08 0.1 0.12
2
|
γ π
|F
0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3
p0 0.01709 ± 0.03113 p0 0.01709 ± 0.03113 p0 0.01709 ± 0.03113 p0 0.01709 ± 0.03113
(a)
This Work: Run I This Work: Fit I approxim. e Pad DA
]
2
[GeV/c
- e
+
e
m
0.02 0.04 0.06 0.08 0.1 0.12 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 p0 0.0115 ± 0.02924 p0 0.0115 ± 0.02924 p0 0.0115 ± 0.02924 p0 0.0115 ± 0.02924
(b)
This Work: Run II This Work: Fit II approxim. e Pad DA
]
2
[GeV/c
- e
+
e
m
0.02 0.04 0.06 0.08 0.1 0.12 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3
p0 0.009552 ± 0.02983 p0 0.009552 ± 0.02983 p0 0.009552 ± 0.02983 p0 0.009552 ± 0.02983
(c)
This Work: Data This Work: Fit approxim. e Pad DA
Philippe Martel - Meson A2 - What have we done 13/26
SLIDE 30
η → e+e−γ [S. Prakov, PRC 95, 035208 (2017)]
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5
2
|
η
|F
1
p0 0.01086 ± 1.006 p1 0.1502 ± 1.931 p0 0.01086 ± 1.006 p1 0.1502 ± 1.931 p0 0.01086 ± 1.006 p1 0.1502 ± 1.931 p0 0.01086 ± 1.006 p1 0.1502 ± 1.931
(a)
This Work: Run I This Work: Run II This Work: Fit I DA (no a2) DA (with a2)
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 1
p0 0.01181 ± 1.001 p1 0.167 ± 2.015 p0 0.01181 ± 1.001 p1 0.167 ± 2.015 p0 0.01181 ± 1.001 p1 0.167 ± 2.015 p0 0.01181 ± 1.001 p1 0.167 ± 2.015
(b)
This Work: Run I This Work: Run II This Work: Fit II DA (no a2) DA (with a2)
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5
2
|
η
|F
1
p0 0.008032 ± 1.004 p1 0.1138 ± 1.968 p0 0.008032 ± 1.004 p1 0.1138 ± 1.968 p0 0.008032 ± 1.004 p1 0.1138 ± 1.968 p0 0.008032 ± 1.004 p1 0.1138 ± 1.968
(a)
This Work: Data This Work: Fit A2, 2014 A2, 2011 TL calculation
- appr. (2014)
e Pad
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 1
(b)
This Work: Data This Work: Fit NA60, In-In NA60, p-A DA (with a2)
- appr. (2015)
e Pad Philippe Martel - Meson A2 - What have we done 14/26
SLIDE 31
ω → π0e+e− [S. Prakov, PRC 95, 035208 (2017)]
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 0.6
2
|
π ω
|F
1 10
p0 0.06585 ± 1.006 p1 0.2483 ± 1.96 p0 0.06585 ± 1.006 p1 0.2483 ± 1.96 p0 0.06585 ± 1.006 p1 0.2483 ± 1.96 p0 0.06585 ± 1.006 p1 0.2483 ± 1.96
(a)
This Work: Run I This Work: Run II This Work: Fit I (s)] Ω (s)=a
1
DA [f ] π 3 → ω DA [full
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 0.6 1 10
p0 0.07699 ± 1.009 p1 0.2758 ± 2.014 p0 0.07699 ± 1.009 p1 0.2758 ± 2.014 p0 0.07699 ± 1.009 p1 0.2758 ± 2.014 p0 0.07699 ± 1.009 p1 0.2758 ± 2.014
(b)
This Work: Run I This Work: Run II This Work: Fit II (s)] Ω (s)=a
1
DA [f ] π 3 → ω DA [full
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 0.6
2
|
π ω
|F
1 10
2
10
p0 0.05113 ± 1.006 p1 0.2057 ± 1.988 p0 0.05113 ± 1.006 p1 0.2057 ± 1.988 p0 0.05113 ± 1.006 p1 0.2057 ± 1.988 p0 0.05113 ± 1.006 p1 0.2057 ± 1.988
(a)
This Work: Data This Work: Fit NA60, In-In VMD TL calculation Caprini, N/D Canterbury appr.
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 0.6 1 10
2
10
(b)
This Work: Data This Work: Fit NA60, p-A Lepton-G ] π 3 → ω DA [full Caprini, DA
]
2
) [GeV/c
- l
+
l m(
0.1 0.2 0.3 0.4 0.5 0.6 1 10
2
10
(c)
This Work: Data This Work: Fit NA60, In-In JPAC, F
NA60 1
+F JPAC, F
NA60 1,2
+F JPAC, F
A2 1
+F JPAC, F
A2 1,2
+F JPAC, F
Philippe Martel - Meson A2 - What have we done 15/26
SLIDE 32
E - γd → ηX [L. Witthauer, PRC 95 055201 (2017)]
Easier to study protons than neutrons, sometimes neutron results unexpected
- Narrow structure previously seen in γn → ηn at W≈1685 MeV
- Seems to only appear in σ1/2 (S11/P11 partial waves)
- Large N(1675)5/2− (MAID) or BnGa with narrow P11 ruled out
η p → p γ
vers (1) vers (2) MAID BnGa
η n → n γ
vers (1) vers (2) MAID BnGa (a) 1500 1600 1700 1800 1500 1600 1700 1800 1900 0.5 1
W [MeV] E asymmetry
Philippe Martel - Meson A2 - What have we done 16/26
SLIDE 33
E - γd → ηX [L. Witthauer, PRC 95 055201 (2017)]
p 1/2
σ
vers (1) vers (2) vers (3) free MAID BnGa
p 3/2
σ
1500 1600 1700 1800 1900 20
- 2
2 4
W [MeV] b] µ [ σ
n 1/2
σ
vers (1) vers (2) vers (3) MAID BnGa (a)
n 3/2
σ
1500 1600 1700 1800 1900 10 20
- 2
2 4
W [MeV] b] µ [ σ
- FIG. 13. Helicity-dependent cross sections
and for the proton (left) and the neutron (right) as a function of the reconstructed
Philippe Martel - Meson A2 - What have we done 16/26
SLIDE 34
E - γd → ηX [L. Witthauer, PRC 95 055201 (2017)]
p 1/2
σ 10 ×
p 3/2
σ
n 1/2
σ 10 ×
n 3/2
σ A
1
A
2
A
MAID BnGa (a) BnGa (b) BnGa (c) 3
A
1500 1600 1700 1800 1500 1600 1700 1800 1500 1600 1700 1800 1500 1600 1700 1800 1900 2 4 6 8
- 0.5
0.5
- 0.5
0.5 1
- 1.5
- 1
- 0.5
0.5 1
W [MeV] b/sr] µ [
i
A
Philippe Martel - Meson A2 - What have we done 16/26
SLIDE 35
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
γp→pπo γn→nπo γp→nπ+ γn→pπ- 1 1.2 1.4 1.6 1.8 2
- 1
1
W[GeV]
- 1
1 -1 1
cos(Θπ) *
- 1
1
Lots of proton data, often missing neutron data
- No free neutron target (I think you’ve heard)
- Can use deuterium (or helium, or...), but FSI
- If FSI are similar for protons and neutrons in deuterium, perhaps the
former can be used to correct the latter
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 36
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
- 1
- 0.5
p(n)) π ( σ fit MAID SAID BnGa
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
1516 MeV
1 2 3 4 5 61528 MeV
1 2 3 4 5 61540 MeV
1 2 3 4 5 61552 MeV
1 2 3 4 5 61564 MeV
1 2 3 4 5 61576 MeV
1 2 3 41588 MeV
1 2 3 41600 MeV
1 2 3 41612 MeV
1 2 3 41624 MeV
1 2 3 41636 MeV
1 2 3 41648 MeV
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
2 4 6 8 10 12 1 2 3 4 5 1 2 3 4 1 2 3 4 5 1 2 3 1 2 0.5 1 1.5 0.5 1
* )
π
θ cos( b/sr] µ [ Ω /d σ d
- 1
- 0.5
n(p)) π ( σ fit MAID SAID BnGa
- 1
- 0.5
W=1312 MeV
- 1
- 0.5
1324 MeV
- 1
- 0.5
1336 MeV
- 1
- 0.5
1348 MeV
- 1
- 0.5
1360 MeV
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
5 10 15 2 4 6 1 2 3 1 2 3 1 2 0.5 1 1.5 2 0.5 1 0.5 1 1.5
* )
π
θ cos( b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 37
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
- 1
- 0.5
n(p)) π ( σ fit MAID SAID BnGa
- 1
- 0.5
W=1312 MeV
- 1
- 0.5
1324 MeV
- 1
- 0.5
1336 MeV
- 1
- 0.5
1348 MeV
- 1
- 0.5
1360 MeV
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
5 10 15 2 4 6 1 2 3 1 2 3 1 2 0.5 1 1.5 2 0.5 1 0.5 1 1.5
* )
π
θ cos( b/sr] µ [ Ω /d σ d
- 1
- 0.5
n) π ( σ fit MAID SAID BnGa
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 1
- 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
5 10 15 2 4 6 1 2 3 1 2 3 1 2 0.5 1 1.5 2 0.5 1 0.5 1 1.5
* )
π
θ cos( b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 38
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
1400 1600 1800 0.5 1 1.5 2 2.5* ) < -0.9
π
θ
- 1.0 < cos(
* ) < -0.8
π
θ
- 0.9 < cos(
*) < -0.7
π
θ
- 0.8 < cos(
* ) < -0.6
π
θ
- 0.7 < cos(
* ) < -0.5
π
θ
- 0.6 < cos(
* ) < -0.4
π
θ
- 0.5 < cos(
* ) < -0.3
π
θ
- 0.4 < cos(
* ) < -0.2
π
θ
- 0.3 < cos(
* ) < -0.1
π
θ
- 0.2 < cos(
* ) < 0.0
π
θ
- 0.1 < cos(
* ) < 0.1
π
θ 0.0 < cos(
1400 1600 1800 1* ) < 0.2
π
θ 0.1 < cos(
1400 1600 1800 1* ) < 0.3
π
θ 0.2 < cos(
1400 1600 1800 1* ) < 0.4
π
θ 0.3 < cos(
1400 1600 1800 1* ) < 0.5
π
θ 0.4 < cos(
1400 1600 1800 0.5 1 1.5 2 2.5* ) < 0.6
π
θ 0.5 < cos(
1400 1600 1800 1* ) < 0.7
π
θ 0.6 < cos(
1400 1600 1800 0.5 1 1.5 2.5* ) < 0.8
π
θ 0.7 < cos(
1400 1600 1800 1* ) < 0.9
π
θ 0.8 < cos(
1400 1600 1800 0.5 1 1.5 2.5p(n) π n(p) π MAID SAID BnGa
1400 1600 1400 1600 1400 1600 1400 1600 1400 1600 1800 0.5 1 1.5 2 2.5 1 2 3 1 2 3 0.5 1 1.5 2 2.5
W [MeV] b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 39
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
1400 1600 1800 0.5 1 1.5 2 2.5* ) < -0.9
π
θ
- 1.0 < cos(
* ) < -0.8
π
θ
- 0.9 < cos(
*) < -0.7
π
θ
- 0.8 < cos(
* ) < -0.6
π
θ
- 0.7 < cos(
* ) < -0.5
π
θ
- 0.6 < cos(
* ) < -0.4
π
θ
- 0.5 < cos(
* ) < -0.3
π
θ
- 0.4 < cos(
* ) < -0.2
π
θ
- 0.3 < cos(
* ) < -0.1
π
θ
- 0.2 < cos(
* ) < 0.0
π
θ
- 0.1 < cos(
* ) < 0.1
π
θ 0.0 < cos(
1400 1600 1800 1* ) < 0.2
π
θ 0.1 < cos(
1400 1600 1800 0.5 1 1.5 2.5* ) < 0.3
π
θ 0.2 < cos(
1400 1600 1800 1* ) < 0.4
π
θ 0.3 < cos(
1400 1600 1800 0.5 1 1.5 2.5* ) < 0.5
π
θ 0.4 < cos(
1400 1600 1800 0.5 1 1.5 2 2.5* ) < 0.6
π
θ 0.5 < cos(
1400 1600 1800 1* ) < 0.7
π
θ 0.6 < cos(
1400 1600 1800 0.5 1 1.5 2.5* ) < 0.8
π
θ 0.7 < cos(
1400 1600 1800 1* ) < 0.9
π
θ 0.8 < cos(
1400 1600 1800 0.5 1 1.5 2.5n π MAID SAID BnGa
1400 1600 1400 1600 1400 1600 1400 1600 1400 1600 1800 0.5 1 1.5 2 2.5 0.5 1 1.5 2 2.5 0.5 1 1.5 2 2.5 0.5 1 1.5 2 2.5
W [MeV] b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 40
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
W [MeV]
1400 1600 1800
b] µ [ σ
10 20 30 40 50 60 70 80
W [MeV]
1400 1600 1800
p
σ /
n
σ
0.4 0.6 0.8 1 1.2
b] [ W [MeV]
1400 1600 1800
b] µ [ σ
10 20 30 40 50 60 70 80
W [MeV]
1400 1600 1800
p
σ /
n
σ
0.4 0.6 0.8 1 1.2 Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 41
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
- 1
/B
1
B
- 1
/B
2
B
- 1
/B
3
B
- 1
/B
4
B
- 1
/B
5
B
- 1
/B
6
B
1400 1600 1800 1400 1600 1800
- 1
1
- 1
1
- 1
W [MeV] /B
i
B
- 1
/B
1
B
- 1
/B
2
B
- 0.5
/B
3
B
0.5/B
4
B
- 1
- 0.5
/B
5
B
- 1
/B
6
B
1400 1600 1800 1400 1600 1800
- 1
1
- 0.5
0.5
- 1
- 0.5
0.5
W [MeV] /B
i
B
Philippe Martel - Meson A2 - What have we done 17/26
SLIDE 42
γp → π0ηp [V. Sokhoyan, PRC 97 055212 (2018)]
Three body final states (decay modes and missing resonances)
[GeV] γ E 1 1.1 1.2 1.3 1.4 b] µ p) [ η π → p γ (
tot
σ 0.5 1 1.5 2 2.5 3 3.5
A2 data (△/), CBELSA/TAPS (⋆/△), GRAAL (♦), old A2 () data; BnGa: total (dash-dotted), ∆(1232)η (dashed), N(1535)π0 (dotted), and a0(980)p (long-dash-dotted); and Mainz: total (solid), resonant (long-dashed), background (dash-double-dotted), and Born (dash-triple-dotted)
Philippe Martel - Meson A2 - What have we done 18/26
SLIDE 43
γd → π0ηX [A. Kaeser, PLB (Submitted)]
- 1
- 0.5
0.5 1 1700 1800 1900 W[MeV] E
γd→pπ0η(n) E (A) γd→pπ0η(n) E (B)
- 0.5
E 1900
- 1
- 0.5
0.5 1 1700 1800 1900 W[MeV] E
γd→nπ0η(p) E (A) γd→nπ0η(p) E (B)
- The two helicity components contribute identically
- True for both participant protons and neutrons
- Absolute couplings for protons and neutrons are identical
- Contributing nucleon resonances (threshold up to inv. masses of 1.9
GeV) have almost equal electromagnetic helicity couplings An,p
1/2 and An,p 3/2
- Typical for ∆ resonances, identical A1/2 and A3/2 components for any
nucleon target only possible for J ≥ 3/2 states, constrains possible
Philippe Martel - Meson A2 - What have we done 19/26
SLIDE 44
γd → π0ηX [A. Kaeser, PLB (Submitted)]
1 2 3 1600 1700 1800 1900 W[MeV] σ[µb] γd→pπ0η(n) σ1/2 (1) γd→pπ0η(n) σ1/2 (2) γd→pπ0η(n) σ1/2 (3) 1 2 3 1600 1700 1800 1900 W[MeV] σ[µb] γd→pπ0η(n) σ3/2 (1) γd→pπ0η(n) σ3/2 (2) γd→pπ0η(n) σ3/2 (3) 1 2 3 1600 1700 1800 1900 W[MeV] σ[µb] γd→nπ0η(p) σ1/2 (1) γd→nπ0η(p) σ1/2 (2) γd→nπ0η(p) σ1/2 (3) 1 2 3 1600 1700 1800 1900 W[MeV] σ[µb] γd→nπ0η(p) σ3/2 (1) γd→nπ0η(p) σ3/2 (2) γd→nπ0η(p) σ3/2 (3)
Philippe Martel - Meson A2 - What have we done 19/26
SLIDE 45
γd → π0ηX [A. Kaeser, PLB (Submitted)]
1 2 3 1600 1700 1800 1900 W[MeV] σ1/2,σ3/2[µb]
γd→pπ0η(n) σ1/2 γd→pπ0η(n) σ3/2
σ ,σ [µb] 1900 1 2 3 1600 1700 1800 1900 W[MeV] σ1/2,σ3/2[µb]
γd→nπ0η(p) σ1/2 γd→nπ0η(p) σ3/2
Philippe Martel - Meson A2 - What have we done 19/26
SLIDE 46
What are we doing
SLIDE 47
G - γp → π0p (K. Spieker, Bonn, Preliminary)
Preliminary results
A2 and CBELSA/TAPS [PRL 109 (2012) 102001] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], MAID-07 [EPJA 34 (2007) 69], and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 20/26
SLIDE 48
G - γp → π0p (K. Spieker, Bonn, Preliminary)
Preliminary results
A2 and CBELSA/TAPS [PRL 109 (2012) 102001] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], MAID-07 [EPJA 34 (2007) 69], and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 20/26
SLIDE 49
G - γp → π+n (K. Spieker, Bonn, Preliminary)
Preliminary results
A2 data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], MAID-07 [EPJA 34 (2007) 69], and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 21/26
SLIDE 50
G - γp → π+n (K. Spieker, Bonn, Preliminary)
Preliminary results
A2 data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], MAID-07 [EPJA 34 (2007) 69], and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 21/26
SLIDE 51
E - γp → π0p (F. Afzal, Bonn, Preliminary)
Preliminary results
A2 and CBELSA/TAPS [PRL 112 (2014) 012003] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], JuBo 2016-3.1, and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 22/26
SLIDE 52
E - γp → π0p (F. Afzal, Bonn, Preliminary)
Preliminary results
A2 and CBELSA/TAPS [PRL 112 (2014) 012003] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], JuBo 2016-3.1, and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 22/26
SLIDE 53
E - γp → π0p (F. Afzal, Bonn, Preliminary)
A2 and CBELSA/TAPS [PRL 112 (2014) 012003] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], JuBo 2016-3.1, and SAID-CM12 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 22/26
SLIDE 54
E - γp → ηp (F. Afzal, Bonn, Preliminary)
Preliminary results
A2 and CBELSA/TAPS [PRL 112 (2014) 012003] data, with BnGa 2014-02 and BnGa 2014-01 [EPJA 50 (2014) 74], JuBo 2016-3.1, and SAID-GE09 [PRC 86 (2012) 015202]
Philippe Martel - Meson A2 - What are we doing 23/26
SLIDE 55
E - γd → π0X (F. Cividini, Mainz, Preliminary)
Philippe Martel - Meson A2 - What are we doing 24/26
SLIDE 56
E - γd → π0X (F. Cividini, Mainz, Preliminary)
Philippe Martel - Meson A2 - What are we doing 24/26
SLIDE 57
E - γd → π0X (F. Cividini, Mainz, Preliminary)
Philippe Martel - Meson A2 - What are we doing 24/26
SLIDE 58
E - γd → π0X (F. Cividini, Mainz, Preliminary)
Philippe Martel - Meson A2 - What are we doing 24/26
SLIDE 59
Talks maybe you now wish you had seen
- F. Cividini (E - γd → π0X - Parallel Session A6)
- C. Collicott (Symmetry violating η decays - Parallel Session C5)
- D. Ghosal (γd → π0π+/−X - Parallel Session A6)
- L. Heijkenskjoeld (Transition Form Factors - Parallel Session B4)
Special shout-out to P. Adlarson, whose paper on η′ → π0π0η was just accepted by PRD, and whose results I did not have time to show after realizing that he was not presenting them here...
Philippe Martel - Meson A2 - What are we doing 25/26
SLIDE 60
Conclusions
- We’ve measured a bunch of stuff
- σ, Σ, T, F, E, G
- Looking at proton and neutron (via deuterium, studying FSI)
- Investigating multi-meson final states
- We’re still measuring stuff
- E and G on proton and neutron
- Recoil observables
- We’ll continuing measuring stuff
- Transition Form Factors
- Future end-point-tagger runs for η′
- Active targets to improve threshold region
Philippe Martel - Meson A2 - What are we doing 26/26
SLIDE 61
Conclusions
- We’ve measured a bunch of stuff
- σ, Σ, T, F, E, G
- Looking at proton and neutron (via deuterium, studying FSI)
- Investigating multi-meson final states
- We’re still measuring stuff
- E and G on proton and neutron
- Recoil observables
- We’ll continuing measuring stuff
- Transition Form Factors
- Future end-point-tagger runs for η′
- Active targets to improve threshold region
- Thank you for your attention!
Philippe Martel - Meson A2 - What are we doing 26/26
SLIDE 62
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
- 1
- 0.5
np,π
0d
π → d γ this work et al. Krusche
- 1
- 0.5
=530 MeV
γ
E
- 1
- 0.5
590 MeV
- 1
- 0.5
660 MeV
- 1
- 0.5
705 MeV
- 1
- 0.5
765 MeV
- 1
- 0.5
832 MeV
- 1
- 0.5
938 MeV
- 1
- 0.5
1028 MeV
- 1
- 0.5
1118 MeV
- 1
- 0.5
1208 MeV
- 1
- 0.5
1312 MeV
- 0.5 0
0.5
- 0.5 0
0.5
- 0.5 0
0.5
- 0.5 0
0.5
- 0.5 0
0.5
- 0.5 0
0.5 2 4 6 1 2
*)
π
θ cos( b/sr] µ [ Ω /d σ (1/A)d
Philippe Martel - Meson A2
SLIDE 63
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
- 1
- 0.5
(np,d) π0 n(p) π0 p(n)+ π
- 1
- 0.5
=488 MeV
γ
E
- 1
- 0.5
502 MeV
- 1
- 0.5
518 MeV
- 1
- 0.5
532 MeV
- 1
- 0.5
548 MeV
- 1
- 0.5
562 MeV
- 1
- 0.5
578 MeV
- 1
- 0.5
592 MeV
- 1
- 0.5
608 MeV
- 1
- 0.5
622 MeV
- 1
- 0.5
638 MeV
- 1
- 0.5
652 MeV
- 1
- 0.5
668 MeV
- 1
- 0.5
682 MeV
- 1
- 0.5
698 MeV
- 1
- 0.5
712 MeV
- 1
- 0.5
728 MeV
- 1
- 0.5
742 MeV
- 1
- 0.5
758 MeV
- 1
- 0.5
772 MeV
- 1
- 0.5
788 MeV
- 1
- 0.5
802 MeV
- 1
- 0.5
818 MeV
- 1
- 0.5
832 MeV
- 1
- 0.5
848 MeV
- 1
- 0.5
862 MeV
- 1
- 0.5
878 MeV
- 1
- 0.5
892 MeV
- 1
- 0.5
908 MeV 922 MeV 938 MeV 952 MeV 968 MeV 982 MeV 998 MeV
- 1
- 0.5
1012 MeV
- 1
- 0.5
1028 MeV
- 1
- 0.5
1042 MeV
- 1
- 0.5
1058 MeV
- 1
- 0.5
1072 MeV
- 1
- 0.5
1088 MeV
- 1
- 0.5
1102 MeV
- 1
- 0.5
1118 MeV
- 1
- 0.5
1132 MeV
- 1
- 0.5
1148 MeV
- 1
- 0.5
1162 MeV
- 1
- 0.5
1178 MeV
- 1
- 0.5
1192 MeV
- 1
- 0.5
1208 MeV
- 1
- 0.5
1222 MeV
- 1
- 0.5
1238 MeV
- 1
- 0.5
1252 MeV
- 1
- 0.5
1268 MeV
- 1
- 0.5
1282 MeV
- 1
- 0.5
1298 MeV
- 1
- 0.5
1312 MeV
- 1
- 0.5
1328 MeV
- 1
- 0.5
1342 MeV
- 1
- 0.5
1358 MeV
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
- 0.5 0 0.5
5 10 15 5 2 4 6 2 4 6 2 4 2 2 4 2 1 2 1 2
* )
π
θ cos( b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2
SLIDE 64
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
600 800 1000 1200 1* ) < -0.9
π
θ
- 1.0 < cos(
* ) < -0.8
π
θ
- 0.9 < cos(
*) < -0.7
π
θ
- 0.8 < cos(
* ) < -0.6
π
θ
- 0.7 < cos(
* ) < -0.5
π
θ
- 0.6 < cos(
* ) < -0.4
π
θ
- 0.5 < cos(
* ) < -0.3
π
θ
- 0.4 < cos(
* ) < -0.2
π
θ
- 0.3 < cos(
* ) < -0.1
π
θ
- 0.2 < cos(
* ) < 0.0
π
θ
- 0.1 < cos(
* ) < 0.1
π
θ 0.0 < cos(
600 800 1000 1200 1* ) < 0.2
π
θ 0.1 < cos(
600 800 1000 1200* ) < 0.3
π
θ 0.2 < cos(
600 800 1000 1200 1 2 3 4* ) < 0.4
π
θ 0.3 < cos(
600 800 1000 1200 1* ) < 0.5
π
θ 0.4 < cos(
600 800 1000 1200 1* ) < 0.6
π
θ 0.5 < cos(
600 800 1000 1200 1* ) < 0.7
π
θ 0.6 < cos(
600 800 1000 1200* ) < 0.8
π
θ 0.7 < cos(
600 800 1000 1200 1 2 3* ) < 0.9
π
θ 0.8 < cos(
600 800 1000 1200 1(np,d) π n(p) π p(n)+ π
800 1000 800 1000 800 1000 800 1000 800 1000 1 2 3 1 2 3 1 2 3 1 2
[MeV]
γ
E b/sr] µ [ Ω /d σ d
Philippe Martel - Meson A2
SLIDE 65
σ - γd → π0X [M. Dieterle, PRC (Accepted)]
[MeV]
γ
E
600 800 1000 1200
b] µ [ σ
20 40 60 80 100 120 140
[MeV]
γ
E
500 1000
p+n
σ /
np
σ
1 1.05 1.1 1.15 Philippe Martel - Meson A2
SLIDE 66
γp → π0ηp [V. Sokhoyan, PRC 97 055212 (2018)]
- 1
- 0.5
0.5 1 H
W
0.3 0.4 0.5 0.6 0.7 =0.95-1.00 GeV
γ
E
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.00-1.05 GeV
γ
E
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.05-1.10 GeV
γ
E
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.10-1.15 GeV
γ
E
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.15-1.20 GeV
γ
E
π
θ cos
- 1
- 0.5
0.5 1 H
W
0.3 0.4 0.5 0.6 0.7 =1.20-1.25 GeV
γ
E
π
θ cos
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.25-1.30 GeV
γ
E
π
θ cos
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.30-1.35 GeV
γ
E
π
θ cos
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.35-1.40 GeV
γ
E
π
θ cos
- 1
- 0.5
0.5 1 0.3 0.4 0.5 0.6 0.7 =1.40-1.45 GeV
γ
E
Philippe Martel - Meson A2
SLIDE 67
γp → π0ηp [V. Sokhoyan, PRC 97 055212 (2018)]
0.5 1 1.5 2 H
W
0.2 0.4 0.6 0.8 =0.95-1.00 GeV
γ
E 0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.00-1.05 GeV
γ
E 0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.05-1.10 GeV
γ
E 0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.10-1.15 GeV
γ
E 0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.15-1.20 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2 H
W
0.2 0.4 0.6 0.8 =1.20-1.25 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.25-1.30 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.30-1.35 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.35-1.40 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2 0.2 0.4 0.6 0.8 =1.40-1.45 GeV
γ
E
Philippe Martel - Meson A2
SLIDE 68
γp → π0ηp [V. Sokhoyan, PRC 97 055212 (2018)]
0.5 1 1.5 2
- I
- 0.4
- 0.2
0.2 0.4 =0.95-1.00 GeV
γ
E 0.5 1 1.5 2
- 0.2
- 0.1
0.1 0.2 =1.00-1.05 GeV
γ
E 0.5 1 1.5 2
- 0.2
- 0.1
0.1 0.2 =1.05-1.10 GeV
γ
E 0.5 1 1.5 2
- 0.2
- 0.1
0.1 0.2 =1.10-1.15 GeV
γ
E 0.5 1 1.5 2
- 0.2
- 0.1
0.1 0.2 =1.15-1.20 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2
- I
- 0.15
- 0.1
- 0.05
0.05 0.1 0.15 =1.20-1.25 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2
- 0.15
- 0.1
- 0.05
0.05 0.1 0.15 =1.25-1.30 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2
- 0.15
- 0.1
- 0.05
0.05 0.1 0.15 =1.30-1.35 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2
- 0.15
- 0.1
- 0.05
0.05 0.1 0.15 =1.35-1.40 GeV
γ
E
] π [rad/
π
φ
0.5 1 1.5 2
- 0.15
- 0.1
- 0.05
0.05 0.1 0.15 =1.40-1.45 GeV
γ
E
Philippe Martel - Meson A2
SLIDE 69
Frozen Spin Target
How are the protons actually polarized? Through Dynamic Nuclear Polarization (DNP):
- Cool target to 0.2 Kelvin.
- Use 2.5 Tesla magnet to align electron spins.
- Pump ≈ 70 GHz microwaves (just above, or below, the Electron Spin
Resonance frequency), causing spin-flips between the electrons and protons.
- Cool target to 0.025 Kelvin, ‘freezing’ proton spins in place.
- Remove polarizing magnet.
- Energize 0.6 Tesla ‘holding’ coil in the cryostat to maintain the
polarization.
- Relaxation times > 1000 hours.
- Polarizations up to 90%.
Philippe Martel - Meson A2
SLIDE 70
Crystal Ball - Charged Particle Detection
Particle Identification Detector (PID)
- Barrel of 24 plastic paddles
- Each covers 15 < θ < 159◦, and
15◦ in φ
- Plot ∆E in PID vs E in NaI
Multiwire Proportional Chamber (MWPC)
- Two chambers: anode wires
sandwiched by two layers of cathode strips
- Voltage between wires and strips
increases when gas is ionized
Philippe Martel - Meson A2
SLIDE 71
TAPS - Charged Particle Detection
Veto scintillators
- 5mm plastic scintillators in front
- f each crystal
- Same method as PID (plot ∆E vs
E) Time of Flight
- Given its increased distance from
the target, massive particles take noticeably longer to reach TAPS
- Plot time vs E, identify nucleons
Philippe Martel - Meson A2
SLIDE 72
Active Target
Requirements
- Polarizable Scintillator
- High light output
- High rate capability
- Low thermal energy input
- Detectors working at 4K
Targets from UMass Amherst Tested at MAMI - Pol > 50%
Neutral Pion Phi (deg) 150 − 100 − 50 − 50 100 150 )
- +N
+
)/(N
- N
+
(N 0.015 − 0.01 − 0.005 − 0.005 0.01 0.015
Philippe Martel - Meson A2