*Work at ASU is supported by the U.S. National Science Foundation

B. G. Ritchie - MENU 2013 - October 2013 1

*Work at ASU is supported by the U.S. National Science Foundation

Barry G. Ritchie*Arizona State University

Latest results from FroST at Jefferson Lab

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=Ex3vgg_jnxltZM&tbnid=4rxlzLCwRB1y3M:&ved=0CAUQjRw&url=http://www.dreamstime.com/royalty-free-stock-photography-europe-cold-snap-frozen-car-image23224277&ei=OV9DUsjZKcPSiwLfu4CoDg&psig=AFQjCNEklQsIWCWYmtJEIUbM6fzvcc3XNQ&ust=1380233286876652

2

Nucleon excited states

γ p → π+ n

B. G. Ritchie - MENU 2013 - October 2013

• As a composite system, the nucleon has a specific spectrum of excitations: the nucleon resonances.

• This nucleon resonance spectrum has many broad overlapping states, making disentangling the spectrum difficult.


The state of our knowledge

22 Δ* states: • 7 with **** • 3 with ***• 7 with **• 5 with *

Nucleon

• Nearly half the states have only fair or poor evidence!

• Most states need more work to learn details

• Are there missing states?26 N* states: • 10 with **** • 5 with ***• 8 with **• 3 with *

4

Models predict (lots of)excitations • Many nucleon models have offered

“predictions” for the nucleon resonance spectrum --• constituent quark model• diquark • collective models• instanton-induced interactions• flux-tube models• lattice QCD• (your favorite here) - BUT…

• THE BIG MYSTERY: Most models

predict many more resonance states than have been observed.


http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=BsdQIxEpT1QJmM&tbnid=dXbwxKvhIdwOjM:&ved=0CAUQjRw&url=http://alamoheightsunitedmethodistchurch.blogspot.com/2011/06/puzzle-pieces.html&ei=SMk7Urdy1PLIAbu8gfAD&psig=AFQjCNGpJ2QEJEHEA-WKSm80Wk4zLHXxDw&ust=1379736261412047


Example: R.G. Edwards et al. Phys. Rev. D87 054506 (2013)

Example: Lattice QCD results for N* resonances• Noticeable change as the π mass

becomes more realistic

• Number of low-lying states (boxed regions) remains the same for the two π-masses, and generally is the same as NRQMs

• Many of these predicted states are poorly determined or missing.

mπ = 524 MeV

mπ = 391 MeV

EXPERIMENT

BARYON MODELS

REACTION MODELAMPLITUDE ANALYSIS

cross sections,spin observables

multipole amplitudes,phase shifts

effective Lagrangians,Isobars, etc…

6

Solving a mystery: “The Case of the Missing Resonances”

LQCD, quark models,etc…


http://www.yourcpapartners.com/blog/wp-content/uploads/2012/01/DooFi_Consulting_detective_with_pipe_and_magnifying_glass_silhouette_.png

7B. G. Ritchie - MENU 2013 - October 2013

Gathering clues:helicity amplitudes

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=sXTbYbR7QGGfDM&tbnid=SxUWalALBXUJAM:&ved=0CAUQjRw&url=http://www.idfpr.com/DPR/appservices/Fingerprint/&ei=YrpEUtO1JNHyigKPhICgDQ&bvm=bv.53217764,d.cGE&psig=AFQjCNGiH20EpaBOrRaM6pvSQKoE_8wowg&ust=1380322271674215

http://www.google.com/url?sa=i&source=images&cd=&cad=rja&docid=us8wZWq-I_rC7M&tbnid=VxZ1dWsIiLvA0M:&ved=0CAgQjRwwAA&url=http://www.dreamstime.com/stock-photography-illustration-art-colorful-fingerprint-white-background-image30197502&ei=HbtEUsyQKM2ZjAKS7oGgBA&psig=AFQjCNGXP_MURHIBHbIwqSrz6SzhNI33xA&ust=1380322461696320


http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=_b7xuSki7sTK4M&tbnid=6_YqCb_SaBMXPM:&ved=0CAUQjRw&url=http://sydneyderbyskates.com/shop/index.php?main_page%3Dproduct_info%26products_id%3D711&ei=bcFEUv3RA8iWiALZ9IGQCg&psig=AFQjCNGYPAx_Q2ytAKinaEdPbUajsT95vA&ust=1380324066958525

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=a07fE-vsDBZSpM&tbnid=TMZEVsO1FsPc5M:&ved=0CAUQjRw&url=http://www.eu-footprint.org/&ei=8cFEUs6eD-bIigKRy4HIBA&psig=AFQjCNFB1srOMz_AzyhqgVP2PTd7DxREHQ&ust=1380324200495768

8

• 8 helicity states: 4 initial, 2 final → 4 2 = 8∙ possible complex amplitudes• Parity reduces these to 4 complex amplitudes Hi (8 W-dependent functions)• Overall phase unobservable → 7 W-dependent functions• Suggests complete determination possible with 7 observables/experiments • HOWEVER, not all possible observables are linearly independent →

a minimum of 8 observables / experiments

Helicity amplitudes for γ + p → p + pseudoscalar

3 12 2

11 22

13 42

H HA

H H

helicity +1 photons (ε+): helicity -1 photons (ε-):31

2 21

4 321

2 12

H HA

H H

,, AeA

→ Parity →

11 12

21 22

A AA

A A

Initial helicity final helicity



9

Linkage between helicity amplitudes and the observables for single pseudoscalar photoproduction

Differential cross section

Beam polarization S

Target asymmetry T

Recoil polarization P

Double polarization observables

• Need at least 4 of the double observables from at least 2 groups for a “complete experiment”

• π0p, π+ n, and η p will be nearly complete

• K+ Λ will be complete!

Long

itudi

nal t

arge

t

Tran

sver

se ta

rget

Pola

rized

ph

oton

s+



Conducting the investigation

B. G. Ritchie – MENU 2013 – Rome 10

Photon beam Target

x y z

Unpolarized 0 T 0

Linearly polarized H (-P) -G

Circularly polarized F 0 -E

FroST

g9b g9a

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=MkdPXzZHS74B4M&tbnid=PxkFWsxAg_l0-M:&ved=0CAUQjRw&url=http://www.100open.com/2011/10/how-diligent-is-your-due-diligence/magnifying-glass/&ei=er1EUsLyJ8j1igLtuIDgCA&psig=AFQjCNEzMAHuFx76XC6O3vOkkmgnPh3p9Q&ust=1380323062148798


The detective’s tools:FroST and friends


http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=2CRKXB0JyDNGQM&tbnid=J2jHZpCnB5l2MM:&ved=0CAUQjRw&url=http://cpcaus.com.au/special&ei=EL5EUteIK-WOiALxkIDQBg&psig=AFQjCNGFcVKy-REnHNDEgB06lhN-9EQqHQ&ust=1380323207149041

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=m-XcyjQ-2BGqAM&tbnid=wErVRxqpfAtyrM:&ved=0CAUQjRw&url=http://bakerstreet.wikia.com/wiki/Deerstalker&ei=Qr5EUqyxC6OEiQL974HADg&psig=AFQjCNEBen2d4VYOXYTc-fp5sE_npXHLSw&ust=1380323247973993

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=MfviWEuAZVX8dM&tbnid=zRLW0Jkq4rRhXM:&ved=0CAUQjRw&url=http://workbench.cadenhead.org/news/3205/mystery-solved-house-like-holmes&ei=aL5EUqSnF-n5iQLIqoDABw&psig=AFQjCNE_-ypZPOLVPJMb85FLdYYdFcRLtA&ust=1380323299122141

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=_IUC5KwJeb8q1M&tbnid=nfrBGe82ZuHUNM:&ved=0CAUQjRw&url=http://blogs.smithsonianmag.com/design/tag/sherlock-holmes/&ei=N79EUqaaMaKRiQLm0YHQDg&psig=AFQjCNF3KiL2G7lxQy4hiMWcmSHg53oeCg&ust=1380323432548625

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=WDjGNXf9qcNBMM&tbnid=51WGJcoKc_3ZhM:&ved=0CAUQjRw&url=http://www.flashlightmuseum.com/USA-Lite-Flashlight-2-Cell-Loive-Drab-Right-Angle-Boy-Scout-Light-with-Small-Safety-Lock-Switch-and-Belt-Clip-2D-1941&ei=KblFUrrEF4quigL7sYDACg&bvm=bv.53217764,d.cGE&psig=AFQjCNH_ZF9Kbjjpxu7FKqY7Hoxvs-BVwg&ust=1380387487013793

CLAS (1997-2012)

Lest we forget: • CLAS was very

good for detecting charged particles

• CLAS had large acceptance



13

Hall B Bremsstrahlung Photon Tagger (not dead yet!)

61 backing counters


• Jefferson Lab Hall B bremsstrahlung photon tagger had:• Eγ = 20-95% of E0

• Eγ up to ~5.5 GeV• Circular polarized

photons with longitudinally polarized electrons

• Oriented diamond crystal for linearly polarized photons

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=WDjGNXf9qcNBMM&tbnid=51WGJcoKc_3ZhM:&ved=0CAUQjRw&url=http://www.flashlightmuseum.com/USA-Lite-Flashlight-2-Cell-Loive-Drab-Right-Angle-Boy-Scout-Light-with-Small-Safety-Lock-Switch-and-Belt-Clip-2D-1941&ei=KblFUrrEF4quigL7sYDACg&bvm=bv.53217764,d.cGE&psig=AFQjCNH_ZF9Kbjjpxu7FKqY7Hoxvs-BVwg&ust=1380387487013793


• Doped butanol and dynamic nuclear polarization): • Butanol with paramagnetic radical

TEMPO• Polarize unpaired TEMPO electrons to

99.999% with B = 5 T and T = 0.3 K• Transfer electron polarization to free

protons with microwaves at ~140 GHz• Remove microwaves• Cool to T = 30 mK and use B = 0.5 T

holding field• Put target in CLAS and run experiment

Frozen Spin Target - FroST


B. G. Ritchie – MENU 2013 - Rome15

Transverse polarization – g9b

Longitudinal polarization – g9a

Complete assembly – g9a

Holding coils

16

• Frozen spin butanol (C4H9OH)

• Pz ≈ 80%

• Target depolarization: τ ≈100 days

FroST performance

• For g9a (longitudinal orientation) 10% of allocated time was used polarizing target

• For g9b (transverse orientation) 5% of allocated time was used polarizing target



FroST’s first clues:Single pion photoproduction

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=MfviWEuAZVX8dM&tbnid=zRLW0Jkq4rRhXM:&ved=0CAUQjRw&url=http://workbench.cadenhead.org/news/3205/mystery-solved-house-like-holmes&ei=aL5EUqSnF-n5iQLIqoDABw&psig=AFQjCNE_-ypZPOLVPJMb85FLdYYdFcRLtA&ust=1380323299122141

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=pHlqeUFy3udQlM&tbnid=nQcFqHgTn6F-HM:&ved=0CAUQjRw&url=https://twitter.com/InFootstepsOf&ei=WsNEUrSvM-rViwLF74GQDw&bvm=bv.53217764,d.cGE&psig=AFQjCNH_ovdBIWoKzgnHKlg6jEA8x3qYJQ&ust=1380324545226176



http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=z3pYNBAh6uxsgM&tbnid=dxFUZK80MWG8IM:&ved=0CAUQjRw&url=http://www.polyvore.com/sherlock_holmes_museum_gift_shop/thing?id%3D33579845&ei=lL9EUpf3FKTBigLRsIGYAw&psig=AFQjCNF3KiL2G7lxQy4hiMWcmSHg53oeCg&ust=1380323432548625

18

Isospin combinations for reactions involving π0 and π+

21

321

21

323

21

321

21

3230

,3/2,3/1:

,3/1,3/2:

IIIIn

IIIIp

Δ+ N*

• Differing isospin compositions for N* and Δ+ for the π0 p and π+ n final states

• The π0 p and π+ n final states can help distinguish between the Δ and N*



Theoretical analyses In the plots that follow, you will see many curves from:• SAID: A two-stage PWA where

• stage 1 is the fit to data• stage 2 is the extraction of resonance parameters

• BnGa (Bonn-Gatchina): A single stage PWA• MAID: Isobar analysis

Note: The SAID results labeled “new” in this section of the talk include the new Σ data from ASU/CLAS. Later sections of the talk show SAID results that do not have the new Σ data included.

20

Observables: T and F


Experiment:• g9b: FroST

Configuration:• Circular photon polarization• Transverse target polarization• Unpolarized photon (add circular beams)• No recoil polarization

Reaction: γ p → n π+

Photon beam Target

x y z

Unpolarized 0 T 0




T for γ p → n π+

• Early stage results• CLAS results agree well with

previous data

(new)

(new)

(new)

g9b:Michael Dugger


F for γ p → n π+

• Early stage results• Predictions get much worse at

higher energies• SAID13 are predictions based

on preliminary fits to CLAS pion Σ measurements

(new) (new)

(new)

g9b: Michael Dugger

23

Observable: E


Configuration:• Circular photon polarization• Longitudinal target polarization• No recoil polarization

Reactions: γ p → p π0 and γ p → n π+

Photon beam Target

x y z

Unpolarized 0 T 0



Experiment:• g9a: FroST


E for γ p → p π0

• Early stage results

• Predictions better at lower energies

(new)

g9a:

Michael Dugger


E for γ p → n π+

Steffen Strauch

PRELIMINARY PRELIMINARY PRELIMINARY PRELIMINARY PRELIMINARY PRELIMINARY

PRELIMINARYPRELIMINARYPRELIMINARYPRELIMINARYPRELIMINARYPRELIMINARY



PRELIMINARYPRELIMINARYPRELIMINARYPRELIMINARYPRELIMINARY

PRELIMINARY

PRELIMINARY PRELIMINARY PRELIMINARY

PRELIMINARY PRELIMINARY PRELIMINARY

Predictions worse at higher energies

SAIDSAID (new)MAID

Cos(θπc.m.)

W = 1.25 GeV W = 1.27 GeV

W = 1.29 GeV W = 1.31 GeV W = 1.33 GeV W = 1.35 GeV

W = 1.47 GeVW = 1.45 GeV

W = 1.43 GeVW = 1.41 GeVW = 1.39 GeVW = 1.37 GeV

W = 1.49 GeV W = 1.51 GeV W = 1.53 GeV W = 1.55 GeV W = 1.57 GeV W = 1.59 GeV

W = 1.71 GeVW = 1.69 GeVW = 1.67 GeVW = 1.65 GeVW = 1.63 GeVW = 1.61 GeV

W = 1.73 GeVW = 1.75 GeV W = 1.77 GeV W = 1.81 GeV W = 1.83 GeV W = 1.9 GeV

W = 2.19 GeVW = 2.13 GeVW = 2.07 GeV

W = 2.02 GeVW = 1.98 GeVW = 1.94 GeV

g9a:

26

Observable: G Reactions: γ p → n π+


Configuration:• Linear photon polarization• Longitudinal target polarization• No recoil polarization

Experiment:• g9a: FroST

Photon beam Target

x y z

Unpolarized 0 T 0




G for γ p → n π+g9a:

▬ SAID-- MAID-• Bonn-Gatch

Jo McAndrew

PRELIMINARY PRELIMINARY

PRELIMINARYPRELIMINARY

W=2030-2080 MeV

W=1640-1680 MeV

W=1840-1880 MeV

W=1475-1500 MeV

• Early stage results

• Photon polarizations are approximate

◊ Bussey et al


Additional clues from FroST:Single eta or kaon photoproduction




29

“Isospin filters”• Final states of ηp and K+Λ systems have isospin ½ , and limit

one-step excited states of the proton to be isospin ½. • Thus, the final states ηp and K+Λ can serve as isospin filters

to the resonance spectrum.

γ p → π+ n γ p → η p


30




Reaction: γ p → η p

Photon beam Target

x y z

Unpolarized 0 T 0



Experiment:• g9b: FroST


T for γ p → η p g9b:Ross Tucker


F for γ p → η p g9b:Ross Tucker

33

Observable: E


Configuration:• Circular photon polarization• Longitudinal Target polarization• No recoil polarization

Reaction: γ p → η p

Photon beam Target

x y z

Unpolarized 0 T 0



Experiment:• g9a: FROST


E for γ p → h p

• Predictions are generally inconsistent with data at all energies at more forward angles

(new)

g9a:

Igor Senderovich

35




Reaction: γ p → K+L and γ p → K0S

Photon beam Target

x y z

Unpolarized 0 T 0



Photon beam Target

x y z

Unpolarized 0 T 0



g9b:

Natalie Walford

W=1725 MeVEγ=1117 MeV












PreliminaryT for γ p → K+L Bonn-Gatchina: blue

kaonMAID: pinkBonn –data - purpleGRAAL data - black













PreliminaryT for γ p → K0S Bonn-Gatchina: blue

kaonMAID: pink

38

A “complete” set of clues:Self-analyzing reaction K+ Y (hyperon)

• Hyperon weak decay allows extraction of hyperon polarization by looking at the decay distribution of the baryon in the hyperon center of mass system:

cos1)(cos 21

YPI

where I is the decay distribution of the baryon, α is the weak decay asymmetry (αΛ= 0.642 and αΣ0 = -⅓ αΛ), and PY is the hyperon polarization.

• Get recoil polarization information without a recoil polarimeter: the reaction is “self-analyzing”.

• No preliminary results yet, but data will be forthcoming.



More clues from FroST: multi-pion photoproduction

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=_IUC5KwJeb8q1M&tbnid=nfrBGe82ZuHUNM:&ved=0CAUQjRw&url=http://blogs.smithsonianmag.com/design/tag/sherlock-holmes/&ei=N79EUqaaMaKRiQLm0YHQDg&psig=AFQjCNF3KiL2G7lxQy4hiMWcmSHg53oeCg&ust=1380323432548625

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=_b7xuSki7sTK4M&tbnid=6_YqCb_SaBMXPM:&ved=0CAUQjRw&url=http://sydneyderbyskates.com/shop/index.php?main_page%3Dproduct_info%26products_id%3D711&ei=bcFEUv3RA8iWiALZ9IGQCg&psig=AFQjCNGYPAx_Q2ytAKinaEdPbUajsT95vA&ust=1380324066958525


40

Photoproduction of π+ π - p states

• 64 observables• 28 independent relations related to helicity amplitude magnitudes• 21 independent relations related to helicity amplitude phases• Results in 15 independent numbers

Good for discovering resonances that decay into other resonances!


41

γ p → p π+ π-


next slide

unpolarized beam and longitudinal target: δl = Λx = Λy = 0

slide after next

longitudinal beam and longitudinal target: δl ≠ 0, Λx = Λy = 0

Spin observable Pz for γ p → p π+ π-


g9a:Sungkyun Park

FSU: Winston Roberts

Fix & Arenhövel

PRELIM

INARY

Spin observable Pz for γ p → p π+ π-


Fix & Arenhövel

s

Yuqing Maog9a:

PRELIM

INARY

44

FroST results in the full CLAS program for photoproduction from proton

σ Σ T P E F G H Tx Tz Lx Lz Ox Oz Cx Cz

Proton target

pπ0 ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓

nπ+ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓

pη ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓

pη’ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓

K+Λ ✔ ✓ ✓ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✔ ✔

K+Σ0 ✔ ✓ ✓ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✔ ✔

K0Σ+ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✔ ✔

✔ - published ✔ - acquired

Not shown in table: ω and ππ photoproduction observables

Preliminary results shown in this talk


Conclusions • Spin observables will

tremendously aid in sleuthing out resonance parameters and finding missing resonances (if they exist)

• Photon experiments in Hall-B with FroST at JLab have acquired hundreds of data points yielding clues to the missing resonances

• For most reaction channels, we will have data sufficient for a nearly complete experiment




Conclusions (cont’d)

• For K Λ and K Σ channels, we will have a complete experiment

• Double-pion observables offer a “next generation” probe of reaction mechanisms and resonances

• Data for some reactions and some observables are nearing the publication stage, but much work remains – STAY ON THE CASE!

http://27gen.files.wordpress.com/2011/06/handprint.jpg


Acknowledgements

CLAS Collaboration

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=wrkkMvOjG9wP9M&tbnid=1EeF2OVJU0DmlM:&ved=0CAUQjRw&url=http://royalsocietypublishing.org/site/librarians/member_glasgow.xhtml&ei=9GFDUp_wC-nNigLvw4H4Cw&bvm=bv.53217764,d.cGE&psig=AFQjCNH4KiyCNBjal_EDZF3zQH_Df9JgWQ&ust=1380234081831479

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=aT5FyaBc0J5dNM&tbnid=nUVQDw3_ISrgnM:&ved=0CAUQjRw&url=http://www.asu.edu/&ei=H2JDUsOaA-KsjALMk4DYBA&psig=AFQjCNGzsJh_zCMddwrf5xfl5O0Nk68kXA&ust=1380234129136052

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=Xm1KjCFhalVe1M&tbnid=4Ngc1kA5gTo8DM:&ved=0CAUQjRw&url=http://collegelogo.blogspot.com/2010/06/university-of-south-carolina-logo.html&ei=X2JDUozxJoGbiALY7oGQDw&psig=AFQjCNGh4R7byN1Fdvb4KVSU9ejdxN6ZHw&ust=1380234181904500

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=yNhXARhMcSj3vM&tbnid=gMaAFOTJB9fizM:&ved=0CAUQjRw&url=http://www.forbes.com/lists/2010/94/best-colleges-10_Catholic-University-of-America_94071.html&ei=lmJDUruWH6LJigLYpYCoCw&psig=AFQjCNGBbzh6xGdHkPL4MVDooUUJJ7fRdQ&ust=1380234240245721

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=v1bZDcZ_cL7RmM&tbnid=g1-5_7dKj5gDcM:&ved=0CAUQjRw&url=http://unhcareercenter.com/florida-state-university-graduate-school/&ei=5WJDUsj1I6TEigLy04GoDQ&psig=AFQjCNEidusXrf9edMtbg_iQ6iyqMu66cg&ust=1380234334347508

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=PgCYVSK-VM_RJM&tbnid=eGvcZkhEAlzvFM:&ved=0CAUQjRw&url=http://logonoid.com/university-of-edinburgh-logo/&ei=C2NDUuq_IsSYiAKh34GYDw&psig=AFQjCNEpq9ih35i4u4HodIF1qHjcgunf5A&ust=1380234369357359

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B. G. Ritchie – MENU 2013 - Rome 48

Molte grazie!

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49

Circ

ular

pol

ariza

tion

Circular polarization from 100% polarized electron beam

• Circular photon beam from longitudinally- polarized electrons

• Incident electron beam polarization

> 85%

2

2

3444

kkkkPP e

Circular beam polarization

k = Eγ/Ee

Coun

ts

H. Olsen and L.C. Maximon, Phys. Rev. 114, 887 (1959) B. G. Ritchie - MENU 2013 - October 2013

50

Linearly polarized photons

• Coherent bremsstrahlung from 50-μ oriented diamond

• Two linear polarization states (vertical & horizontal)

• Analytical QED coherent bremsstrahlung calculation fit to actual spectrum (Livingston/Glasgow)

• Vertical 1.3 GeV edge shown


51

FroST target • Butanol composition: C4H9OH

• C and O are even-even nuclei → No polarization of the bound nucleons

• Carbon target used to represent bound nucleon contribution of butanol



Slide from Chris Keith

FroST target



FroST target

*Work at ASU is supported by the U.S. National Science Foundation

Documents

Transcript of *Work at ASU is supported by the U.S. National Science Foundation