the prex and crex experiments - 東北大学原子核 … · the prex and crex experiments ......

The PREX and CREX Experiments Measurements of Parity-Violating Electron Scattering

Asymmetries off 208Pb and 48Ca:The first PREX Result at Jefferson Laboratory and Future Plans

Krishna S. KumarUniversity of Massachusetts, Amherst

Acknowledgements: C. Horowitz

The PREX, CREX and Hall A Collaboration and the Accelerator Division at Jefferson Laboratory

3rd International Symposium on Nuclear Symmetry Energy, NSCL/FRIB, East Lansing, MI

July 25, 2013

Krishna S. Kumar The PREX and CREX Experiments at JLab

Outline

Introduction to Parity-Violating Electron ScatteringRelativistic electron scattering and substructureParity Violation (PV) in weak interactionsNeutral weak interactionsOverview of an electron beam parity violation experiment

PREX at Jefferson LaboratoryExperimental technique

Unique features of Jefferson Lab Hall APhysics Run (March-June 2010)

PREX first resultFuture Plans

Improvements for Approved PREX-II ApparatusRecent PAC Approval of the CREX ExperimentNew idea for an improved Pb measurement at Mainz

Conclusion and Outlook

2

PRL 108 (2012) 112502PRC 85 (2012) 032501


Outline







2

Challenging experimental technique has been

successfully demonstrated

PRL 108 (2012) 112502PRC 85 (2012) 032501


Outline







2

Challenging experimental technique has been

successfully demonstrated

Definite plans to obtain higher statistics

PRL 108 (2012) 112502PRC 85 (2012) 032501

Krishna S. Kumar Parity-Violating Electron Scattering: MeV to TeV Physics

Introduction to Parity-Violating

Electron Scattering

3


Relativistic Electron Scattering

4

e

e

γ

Differential Cross Section

Heavy, spinlessnucleus

� d⇥

d�

⇥

Mott=

4Z2�2E2

q4

and nuclear size

Q2: -(4-momentum)2 of the virtual photon

€

q2 = −4E ʹ′ E sin2 θ2

4-momentum transfer


Relativistic Electron Scattering

4

e

e

γ

Differential Cross Section

Heavy, spinlessnucleus

� d⇥

d�

⇥

Mott=

4Z2�2E2

q4

d�

d�=

⇥d�

d�

⇤

Mott

�� F (q)��2

Neglec&ng recoil, form factor F(q) is the Fourier transform of charge distribu&on

As Q increases, nuclear size modifies formula

and nuclear size

Q2: -(4-momentum)2 of the virtual photon

€

q2 = −4E ʹ′ E sin2 θ2

4-momentum transfer


Measurement Approach

5

€

APV ≈GFQ

2

4πα 2Fn Q

2( )Fp Q

2( )

An Electroweak Observable Sensitive to the Neutron RMS Radius

v090M

Sk7HFB-8

SkP

HFB-17SkM

*

Ska

Sk-RsSk-T4

DD-ME2

DD-ME1

FSUGold

DD-PC1PK1.s24

NL3.s25

G2

NL-SV2PK1NL3

NL3*

NL2NL1

0 50 100 150 L (MeV)

0.1

0.15

0.2

0.25

0.3

!rnp

(fm

)

Linear Fit, r = 0.979Nonrelativistic modelsRelativistic models

D1S

D1NSG

II

Sk-T6SkX SLy5

SLy4

MSkA

MSL0

SIVSkSM

*SkM

P

SkI2SV

G1

TM1

NL-SHNL-RA1

PC-F1

BCP

RHF-PKO3

Sk-Gs

RHF-PKA1PC-PK1

SkI5

Roca-Maza et al

Mean Field Theory fit mostly by data other than neutron densities

electroweak probe

R. Furnstahl


Measurement Approach

5

€

APV ≈GFQ

2

4πα 2Fn Q

2( )Fp Q

2( )

An Electroweak Observable Sensitive to the Neutron RMS Radius

v090M

Sk7HFB-8

SkP

HFB-17SkM

*

Ska

Sk-RsSk-T4

DD-ME2

DD-ME1

FSUGold

DD-PC1PK1.s24

NL3.s25

G2

NL-SV2PK1NL3

NL3*

NL2NL1

0 50 100 150 L (MeV)

0.1

0.15

0.2

0.25

0.3

!rnp

(fm

)


D1S

D1NSG

II

Sk-T6SkX SLy5

SLy4

MSkA

MSL0

SIVSkSM

*SkM

P

SkI2SV

G1

TM1

NL-SHNL-RA1

PC-F1

BCP

RHF-PKO3

Sk-Gs

RHF-PKA1PC-PK1

SkI5

Roca-Maza et al


electroweak probe

R. Furnstahl

In the following, I focus on the measurements; other talks, including the

one following mine, address interpretation and potential implications

Note: R. Michaels (JLab) here during the last week


Weak Interactions

6

Fermi Theory for weak interactionsNeutron & nuclear β Decay

“Effective” low energy theory that explains many observed properties of radioactive nuclear decays

Universal strength: coupling constant GF

charge and flavor-changing


Weak Interactions

6




€

x,y,z→−x,−y,−zparity transformation (reflection)

�p = ��p�L = �L

�s = �s

Observed NOT to be invariant under parity transformations



Weak Interactions

6




Weak decay of60Co Nucleus

60Co

60Ni

€


�p = ��p�L = �L

�s = �s


observed anisotropy in beta-emission when nuclei aligned to a magnetic field

signature of parity violation1957



Weak Interactions

6

Fermi Theory for weak interactions



Weak decay of60Co Nucleus

60Co

60Ni

€


�p = ��p�L = �L

�s = �s


observed anisotropy in beta-emission when nuclei aligned to a magnetic field

signature of parity violation1957

B

observed not observed

ν-

e -

e-

ν-reflection


Charge/Flavor Conserving Analog?

7

Zel’dovich speculation: Is Electron Scattering Parity-Violating?

1958



7

Neutron β Decay Electron-protonWeak Scattering


1958



7


Parity-violating


1958



7


Parity-violating

θE

E’

€

Q2 = 4E ʹ′ E sin2 θ2

4-momentum transfer


1958


Parity Violation Signature

8

How to observe parity violation in electron scattering

p pp

p

pe-

p

e-

e-

e-longitudinallypolarized

e-e-reflection

rotation



8

•One of the incident beams longitudinally polarized•Change sign of longitudinal polarization•Measure fractional rate difference


p pp

p

pe-

p

e-

e-


e-e-reflection

rotation



8

•One of the incident beams longitudinally polarized•Change sign of longitudinal polarization•Measure fractional rate difference

€

10−4 ⋅Q2APV ~ (GeV2)


p pp

p

pe-

p

e-

e-


e-e-reflection

rotation


Neutral Weak Interaction Theory

9

Glashow, Weinberg and Salam: SU(2)L X U(1)Y

W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge

One free parameter: weak mixing angle θW

Z Charge

€

T − qsin2θW

€

−qsin2θW

The Z boson incorporated



9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

μ

νμ W+

-

Charged Current




9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current




9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current


g

cos ✓WZµ

¯f�µ(T3f � 2Qf sin

2 ✓W � T3f�5)f, T3f = ±1/2f fZ0



9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current


Do lepton-nucleon neutral current interactions exhibit parity violation?

g

cos ✓WZµ


2 ✓W � T3f�5)f, T3f = ±1/2f fZ0

Parity is violated

Parity is conserved

APV ⇠ 10�4

Weinberg model



9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current



g

cos ✓WZµ


2 ✓W � T3f�5)f, T3f = ±1/2f fZ0

First table-top atomic parity violation searches: negative!

Parity is violated

Parity is conserved

APV ⇠ 10�4

Weinberg model



9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current



g

cos ✓WZµ


2 ✓W � T3f�5)f, T3f = ±1/2f fZ0


Parity is violated

Parity is conserved

APV ⇠ 10�4

Weinberg model

large rate at large Q2

electron-nucleon deep inelastic

scatteringdiscovery of scaling

M. Breidenbach et al.



9


W Charge

Left- Right-

zero

€

T = ±12€

0,±1,± 13,± 23

€

0,±1,± 13,± 23γ Charge


Z Charge

€

T − qsin2θW

€

−qsin2θW

νμ

νμ Z0

Neutral Current

μ

νμ W+

-

Charged Current



g

cos ✓WZµ


2 ✓W � T3f�5)f, T3f = ±1/2f fZ0


Parity is violated

Parity is conserved

APV ⇠ 10�4

Weinberg model

large rate at large Q2

electron-nucleon deep inelastic

scatteringdiscovery of scaling

M. Breidenbach et al.

pressing problem in mid-70’s

Z*?

e- e-

N X


Anatomy of a Parity Experiment

10

C.Y. Prescott, et al.



10


² Beam helicity sequence is chosen pseudo-randomly• Helicity state, followed by its complement• Data analyzed as “pulse-pairs”



10


• Beam Monitors to measure helicity-correlated changes in beam parameters

• High-power cryotarget 30 cm long for high luminosity



10


• Polarimetry



10


• Magnetic spectrometer directs flux to background-free region

• Flux Integration measures high rate without deadtime


-810 -710 -610 -510 -410 -310-1010

-910

-810

-710

-610

-510

-410

PVeS Experiment Summary

100%

10%

1%

0.1%

G0

G0

E122

Mainz-Be

MIT-12C

SAMPLE H-I

A4A4

A4

H-IIH-He

E158

H-III

PVDIS-6

PREX-IPREX-II

CREX

Qweak

SOLID

MollerMESA-P2

MESA-12CILC-MOLLER

PioneeringNuclear Studies (1998-2010)S.M. Study (2003-2012)Future

PVA

)PV

(Aδ

3 Decades of Technical Progress

11

photocathodes, polarimetry, high power cryotargets, nanometer beam stability, precision beam diagnostics, low noise electronics, radiation hard detectors

•Beyond Standard Model Searches•Strange quark form factors•Neutron skin of a heavy nucleus•QCD structure of the nucleon

SLACMIT-Bates

MainzJefferson Lab

• sub-part per billion statistical reach and systematic control• sub-1% normalization control

Parity-violating electron scattering has become a precision tool

Mainz & MIT-Bates in the mid-80sJLab program launched in the mid-90s

Continuous interplay between probing hadron structure and electroweak physics

E158 at SLAC measured PV Møller scattering

State-of-the-art:


PREX at Jefferson Lab

12

22

208Pb208Pb208Pb208Pb


PREX Concept

13

γ

€

MEM =4παQ2

Fp Q2( )

€

MPVNC =

GF21− 4sin2θW( )Fp Q2( ) − Fn Q2( )[ ]

€

APV ≈GFQ

2

4πα 2Fn Q

2( )Fp Q

2( )proton neutron

Electric charge 1 0

Weak charge ~0.08 -‐1

Q2 ~ 0.01 GeV2

APV ~ 0.6 ppmRate ~ 1 GHz

5o scattering angle

Pb-Radius EXperiment

QpEM ~ 1 Qn

EM ~ 0

QpW ~ 1 - 4sin2θWQn

W ~ -1

δ(APV) ~ 20 ppb!


PREX Concept

13

γ

€

MEM =4παQ2

Fp Q2( )

€

MPVNC =

GF21− 4sin2θW( )Fp Q2( ) − Fn Q2( )[ ]

€

APV ≈GFQ

2

4πα 2Fn Q

2( )Fp Q

2( )proton neutron

Electric charge 1 0


Q2 ~ 0.01 GeV2


5o scattering angle


QpEM ~ 1 Qn

EM ~ 0


W ~ -1

0 0.4 0.8 1.2 1.6q(fm-1)

0

0.2

0.4

0.6

0.8

1

F wk(

q)

48Ca [0.207(6)]208Pb[0.223(6)]PREX [0.204(28)]

FSUGoldqC

REX

J. Piekarewicz

v090M

Sk7HFB-8

SkP

HFB-17SkM

*

Ska

Sk-RsSk-T4

DD-ME2

DD-ME1

FSUGold

DD-PC1PK1.s24

NL3.s25

G2

NL-SV2PK1NL3

NL3*

NL2NL1

0 50 100 150 L (MeV)

0.1

0.15

0.2

0.25

0.3

!rnp

(fm

)


D1S

D1NSG

II

Sk-T6SkX SLy5

SLy4

MSkA

MSL0

SIVSkSM

*SkM

P

SkI2SV

G1

TM1

NL-SHNL-RA1

PC-F1

BCP

RHF-PKO3

Sk-Gs

RHF-PKA1PC-PK1

SkI5Roca-Maza et al


electroweak probe

R. Furnstahl

δ(APV) ~ 20 ppb!


PREX Concept

13

γ

€

MEM =4παQ2

Fp Q2( )

€

MPVNC =

GF21− 4sin2θW( )Fp Q2( ) − Fn Q2( )[ ]

€

APV ≈GFQ

2

4πα 2Fn Q

2( )Fp Q

2( )proton neutron

Electric charge 1 0


Q2 ~ 0.01 GeV2


5o scattering angle


QpEM ~ 1 Qn

EM ~ 0


W ~ -1

0 0.4 0.8 1.2 1.6q(fm-1)

0

0.2

0.4

0.6

0.8

1

F wk(

q)

48Ca [0.207(6)]208Pb[0.223(6)]PREX [0.204(28)]

FSUGoldqC

REX

J. Piekarewicz

v090M

Sk7HFB-8

SkP

HFB-17SkM

*

Ska

Sk-RsSk-T4

DD-ME2

DD-ME1

FSUGold

DD-PC1PK1.s24

NL3.s25

G2

NL-SV2PK1NL3

NL3*

NL2NL1

0 50 100 150 L (MeV)

0.1

0.15

0.2

0.25

0.3

!rnp

(fm

)


D1S

D1NSG

II

Sk-T6SkX SLy5

SLy4

MSkA

MSL0

SIVSkSM

*SkM

P

SkI2SV

G1

TM1

NL-SHNL-RA1

PC-F1

BCP

RHF-PKO3

Sk-Gs

RHF-PKA1PC-PK1

SkI5Roca-Maza et al


electroweak probe

R. Furnstahl

δ(APV) ~ 20 ppb!

as direct as it gets!


PREX Overview

14

A B C

D1 GeV electron beam, 50-70 µAhigh polarization, ~89%helicity reversal at 120 Hz

0.5 mm isotopically pure 208Pb target5° scattered electrons Q2 =0.0088 GeV2/c2

new thin quartz detectors


HRS at JLab

15

Flux Integration TechniqueHAPPEX: 2 MHz

HAPPEXII: 100 MHz PREX: 1 GHz

ElasticInelastic detector

Q Q

Dipole

Quad

target

Hall A High Resolution Spectrometers


HRS at JLab

15

Flux Integration TechniqueHAPPEX: 2 MHz

HAPPEXII: 100 MHz PREX: 1 GHz

ElasticInelastic detector

Q Q

Dipole

Quad

target pure, thin 208Pb target

~10 cm

hardware resolution: ∆p/p ~ 10-3

Hall A High Resolution Spectrometers


“Parity Quality” Beam

16

•Active feedback of charge asymmetry•Careful laser alignment•Precision beam position monitoring•Active calibration of detector slopes

Aphys ~ 500 ppb Acorr = Adet - AQ + α ΔE+ Σβi Δxi


raw average: ~ 20 nm


16



mic

rons




16


2 methods of “slow” reversal


mic

rons




16

Electron Beam


2 methods of “slow” reversal

Sign flips using ½ wave plate & Wien filter ++ -+ +- --

corrections:< 5 nm or 100 ppb


mic

rons


Aspects of the Apparatus

17


Raw Asymmetry Data

18

171 ppm width@ 30 Hz

integrated rate ~ 1 GHz

120 Hz flipping

Statistical behavior of data consistent with detector noise being

dominated by electron counting statistics

Grand averages of all 4

combinations of slow reversal

flips are statistically consistent

606 ± 113496 ± 107566 ± 095685 ± 092

594 ± 50parts per billion (ppb)

systematic error due to beam

fluctuations: 7 ppb

Physics Data: April/May 2010

parts per million # std. deviations


Normalization Errors

19

Systematic Error Absolute (ppm)

Relative ( %)

Polarization 0.0083 1.3

Detector Linearity 0.0076 1.2Beam current normalization

0.0015 0.2

Rescattering 0.0001 0

Transverse Polarization

0.0012 0.2

Q2 0.0028 0.4

Target Backing 0.0026 0.4

Inelastic States 0 0

TOTAL 0.0140 2.1

Goal for total systematic error ~ 2% achieved!



19


Relative ( %)



0.0015 0.2



0.0012 0.2

Q2 0.0028 0.4



TOTAL 0.0140 2.1


€


4-momentum transfer

E: spin precession in machineE’: NMR in HRS B fieldscattering angle: survey ~ 1 mr

Q2 distribution obtained by low rate runs; trigger on quartz pulse-height

calibration



19


Relative ( %)



0.0015 0.2



0.0012 0.2

Q2 0.0028 0.4



TOTAL 0.0140 2.1


€


4-momentum transfer

E: spin precession in machineE’: NMR in HRS B fieldscattering angle: survey ~ 1 mr

Q2 distribution obtained by low rate runs; trigger on quartz pulse-height

calibration

Sca<ered Electron Energy

Absolute angle calibration via nuclear recoil

variation

Water cell target

Recoil is large for H, small for nuclei

0.2% absolute calibration achieved:0.4% on Q2


Final Result

20

Rn

Mean Field and Other ModelsAtomic Parity

ViolaDon

Assume surface thickness good to 25% (MFT)

Neutron density at one Q2

Small correcDons for MEC

Neutron Stars

Weak density at one Q2

Correct for Coulomb DistorDons

Measured APV

FW (q̄) = 0.204± 0.028(exp)

±0.001(model) fm

Rn = 5.751± 0.175(exp)

±0.026(model)

±0.005(strange) fm

q̄ = 0.475 fm�1

PRL 108 (2012) 112502 PRC 85 (2012) 032501


The Neutron Skin

21First electroweak indication of a neutron skin of a heavy nucleus (CL ~ 90-95%)

Rn �Rp = 0.302± 0.175(exp)± 0.026(model)± 0.005(strange) fm


PREX-II Proposal

22

Achieve original proposal goal for accumulated statistics


New Beamline Design

23

•Redesign beamline seals to eliminate o-ring•Neck down tungsten collimator to confine neutrons to one location and add water cooling•Neutrons moderated by new shielding•Small adjustment to septum current will realize an additional ~25% gain in statistical reach


PREXII Proposal

24

PREx II improvements• Metal o-‐rings• RadiaAon hard electronics• Reduce neutron backgrounds

Recent Rn predicDons:

Hebeler et al. Chiral EFT calcula2on of neutron ma7er. Correla2on of pressure with neutron skin by Brown. Three-‐neutron forces!

Steiner et al. X-‐Ray n-‐star mass and radii observa2on + Brown correla2on. (Ozel et al finds soJer EOS, would suggest smaller Rn).

Tamii et al. Measurement of electric dipole polarizability of 208Pb + model correla2on with neutron skin.

Tsang et al. Isospin diffusion in heavy ion collisions, with Brown correla2on and quantum molecular dynamics transport model.

δ(APV)/APV ~ 3%δ(Rn)/Rn ~ 1%

PREX-‐II

(Summ

er 2015)

Full precision in 25 additional PAC daysPresented to JLab PAC in June 2011: Approved with strong endorsement

HebelerSteinerTamiiTsang

δ(Rn) ~ ± 0.06 fm


PREXII Proposal

24

PREx II improvements• Metal o-‐rings• RadiaAon hard electronics• Reduce neutron backgrounds

Recent Rn predicDons:

Hebeler et al. Chiral EFT calcula2on of neutron ma7er. Correla2on of pressure with neutron skin by Brown. Three-‐neutron forces!

Steiner et al. X-‐Ray n-‐star mass and radii observa2on + Brown correla2on. (Ozel et al finds soJer EOS, would suggest smaller Rn).

Tamii et al. Measurement of electric dipole polarizability of 208Pb + model correla2on with neutron skin.

Tsang et al. Isospin diffusion in heavy ion collisions, with Brown correla2on and quantum molecular dynamics transport model.

δ(APV)/APV ~ 3%δ(Rn)/Rn ~ 1%

PREX-‐II

(Summ

er 2015)

Full precision in 25 additional PAC daysPresented to JLab PAC in June 2011: Approved with strong endorsement

HebelerSteinerTamiiTsang

How badly does the community want this?

δ(Rn) ~ ± 0.06 fm


CREX Proposal

25

Measurement of APV in elastic scattering off 48Ca

Approved by PAC last month!

Important Workshop in March 2013 at JLab


CREX at JLab

26

δ(Rn) ~ ± 0.02 fm

G. Hagen et al

PRL 109 (2012) 032502test coupled

cluster models

Approved by JLab PAC in Summer 2013


CREX at JLab

26

δ(Rn) ~ ± 0.02 fm

G. Hagen et al


cluster models


separate elastic events cleanly


CREX at JLab

26

δ(Rn) ~ ± 0.02 fm

G. Hagen et al


cluster models


Could run in 2016 depending

on schedule and funding

separate elastic events cleanly


FRIB and PVES

27

• Less precise measurements of thicker neutron skins with radioactive beams complimentary to precise parity violating measurements on stable nuclei.

Neutron skins predicted by average of 4 Skyrme energy functionals smoothly increase with neutron #. 48Ca skin slightly larger than 208Pb.

Skin of Ca isotopes increases with N. Example measure (nearly twice as large vs 48Ca?) skin in 54Ca with hadronic probe using radioactive beam. Calibrate hadronic reaction mechanism by comparing with CREX for 48Ca.

48Ca54Ca

Kortelain et al. ArXiv:1307.4223

C. Horowitz


Improved 208Pb Rn?

28

200 MeV FOM peaks around 25 degrees

S. Ban and C. Horowitz

C. SfientiM. Thiel

K.K.

Explore a PREX-style

measurement usingsame

solenoidal magnet to be used for P2


solenoidal spectrometer will separate inelastics over the full range of the azimuth

Improved 208Pb Rn?

28



C. SfientiM. Thiel

K.K.





solenoidal spectrometer will separate inelastics over the full range of the azimuth

Improved 208Pb Rn?

28



C. SfientiM. Thiel

K.K.




δ(Rn) ~ ± 0.03 fm


Conclusions

29

PREX produced the first electroweak measurement of the neutron RMS radius in a heavy nucleusMany new technical challenges overcome

High luminosity Pb targetPrecision 1 GeV polarimetrySpectrometer optics optimization to produce compact elastic footprint“Parity quality” beamPb transverse asymmetry measured and introduces negligible uncertaintyNovel integrating detectors can count at GHz rates

Followup run approved by JLab PAC in Summer 2011Likely to be scheduled to run in mid-2015 (after first commissioning of beams after JLab upgrade shutdown)

Potential for precise Rn measurements demonstratedPREX-II: allocated the beam time and demonstrated ability to achieve ±0.06 fmCREX approved: 48Ca Rn goal: ±0.02 fmPotential to measure 208Pb to ±0.03 fm at Mainz


Personal Remarks

We are in an era of constrained budgetsPREX and CREX running time must compete with a diverse programHow important are these measurements to the community?

I believe these measurements form critical anchors for Symmetry Energy constraintsBut if the community is lukewarm about these measurements, they wont happen!So, if you are enthusiastic about these measurements, keep making it known!For example, a Mainz experiment will not materialize unless there is sustained interest

Shameless plugI am about to advertise for a postdoc position to work on JLab PV program

Please direct your best graduating students to look for my ad in the next few weeks!

30

Thank you for your support:critical for obtaining beamtime allocation for PREX-I

the prex and crex experiments - 東北大学 原子核 … · the prex and crex experiments ......

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the prex and crex experiments - 東北大学原子核 … · the prex and crex experiments ......