Polarized d+d elastic scattering at E d =231.8 MeV

Polarized d+d elastic scattering at Ed=231.8 MeV

IUCFA. Micherdzinska, C.E. Allgower, A.D. Bacher, C. Lavelle,

H. Nann, J. Olmsted, T. Rinckel, E.J. StephensonW. Michigan U. P.V. Pancella

Minnesota State U. M.A. Pickar Ohio U. J. Rapaport

Hillsdale College A. Smith

Talk sketch

• Motivation• Experimental setup

• Measurement plan for Tkq and cross section

for

• Tkq and cross section data and theoretical calculations (A. Fonseca)

• Summary

ddDd 2

π0

CHARGE SYMMETRY (CS)

Physics is unchanged when protons and neutrons are interchanged

d + d 4He + π0

d + d d + d

To calculate this we need to describe entrance channel interaction.

To do this, we measured σ(Θ), Tkq(Θ) for

MOTIVATION

Ed=231.8 MeV

The observation (E. Stephenson et al. Phys. Rev. Lett. 91 (2003) 142302) demonstrates that CS is broken

Ed=231.8 MeV

π0 is odd under CS

?d

d

4He

2002 IUCF

Completed data taking in search for d + d 4He + π0

Last week of beam time was spent for d + d d + d at 231.8 MeV (changing experimental setup)

PINTEX detector system

Ideal Polarization Valuespy pyy required RF transition 1 1 MF 3:4 and SF 2:6-1 1 MF 1:4 and WF 0 1 MF 1:4 and SF 2:6 0 -2 MF 1:4 and SF 3:5 0 0 none CIPIOS can produce these

values with an efficiency of 80-90%.

2002 IUCF

d beam

WC1

WC2

KE

V

F Si Barrel

target (D2, H2 or HD)

Si Barrel

PINTEX detector system

dddd

pd d,dpd,d

pdpd

Det. Thickness Radius

(mm) (mm)

F 1.5 203

K 153 423

E 103 369

Si Barrel – 3 rings of 6 Si detector, each 28 strips

1st ring: 1mm

2nd ring: 1mm

3rd ring: 0.5mm

σdp(θ) K. Ermisch Phys. Rev C68 051001 (2003)

We can find Py, Pyy

pd d,dpd,d

pdpd

dddd

We know: Tkq K. Sekiguchi Phys. Rev C65, 034003 (2002)

We know Py, Pyy

We can find Tkq, unnormalized σdd(θ)

We can find normalization factor Ndd/Ndp

and normalize σdd(θ)

Experimental issues:

unknown beam polarization

unknown luminosity

extrapolated Tkq for 231.8 MeV (theory + experiment)

pdpd

d beam

H2 target

F

WC1

WC2K E

V2 charged particles registered in forward angles: dp, pp

We have complete energy and angle information

p

d

TRIGGER

H2 target

d beam

F

WC1

WC2K E

V

d

TRIGGER

1 forward prong in coincidence with at least 1 recoil is Si barrel dd, dp, pp

We can reconstruct azimuthal angle and energy losses

dddd

D2 target

D2 target

d

pdpd

Particle identification (1-p, 2-d)

If Θ1 > 37o o.k

Else if E1 < E2 switch 1 2

coplanarity

energy cut Ep+Ed=231.8MeV

Extracting dp elastic scattering events

pd kinematic curve

+

+

pd kinematic curve

pdpd

calcd

datad θθθD

Ntrue= Ntot- F(NL+NR)

F(NL+NR)=NM

Subtraction of dp breakup

for each spin state

)2cos)(4

3)(

8

1cos)(31)((),( 222011 yyyyy pTpTpiT

yy

y

yy

pTdH

piTdG

pTdF

220

2

0

110

2

0

20

2

0

0

4

32cos)(

3cos)(

]8

11[2)(

Elastic scattering polarized cross section

Cosine portion of Fourier series of azimuthal angle:

Finding Py, Pyy

Solve for Py, Pyy

)2coscos),( HGF

notches

pdpd

pdpd

)2cos)(4

3)(

8

1cos)(31)((),( 222011 yyyyy pTpTpiT

yy

y

yy

pTdH

piTdG

pTdF

220

2

0

110

2

0

20

2

0

0

4

32cos)(

3cos)(

]8

11[2)(

Elastic scattering polarized cross section

Cosine portion of Fourier series of azimuthal angle:

Finding Py, Pyy

Solve for Py, Pyy

)2coscos),( HGF

cosΦ cos2Φ Py Pyy

nom. exp exp nom.

1 0.68±0.02 0.79±0.05 1

-1 -0.62±0.02 0.58±0.05 1

0 0.00±0.02 0.74±0.05 1

0 -0.00±0.01 -1.85±0.05 -2

pdpd

Py, Pyy

Averaged values of Py and Pyy

Py and Pyy do not depend on the polar angle Ө

dddd

Particle identification :

Forward detectors

Silicon Barrel –backward ring middle ring forward ring

Extracting dd elastic scattering events

coplanarity

+

dddd

Breakup subtraction model

total peak with background

dp quasi-elastic peak (from pd breakup data) and dd breakup (model)

dd peak after background subtraction

2 components:

- General background from breakup into dpn or ppnn

- d+p quasi elastic scattering

breakup

dddd

)2coscos),( HGF

yy

y

yy

pTdH

piTdG

pTdF

220

2

0

110

2

0

20

2

0

0

4

32cos)(

3cos)(

]8

11[2)(

Elastic scattering polarized cross section

yy

y

yy

p

HT

p

GiT

p

FT

3

4

3

2

)1(8

22

11

20

Cosine portion of Fourier series of azimuthal angle:

→

Remove σo in division by unpolarized state, normalized by relative luminosity.

Knowing py and pyy and fitting F, G, H to azimuthal distribution we can find analyzing power

original (with notches)

azimuthal distribution

dddd

)2coscos),( HGF

yy

y

yy

pTdH

piTdG

pTdF

220

2

0

110

2

0

20

2

0

0

4

32cos)(

3cos)(

]8

11[2)(

Elastic scattering polarized cross section

yy

y

yy

p

HT

p

GiT

p

FT

3

4

3

2

)1(8

22

11

20

Cosine portion of Fourier series of azimuthal angle:

→

Knowing py and pyy and fitting F, G, H to azimuthal distribution

we can find analyzing power

azimuthal distributions divided by

unpolarized spectrum

dddd

Analyzing power values for each spin state

Do not depend on polarization – good analysis !

Calculation by A. Fonseca

state1

state 2

state 3

state 4

dddd

Averaged values of analyzing power

Calculation by A. Fonseca

dddd

dp

dp

dd

dp

dp

dddpdd

N

Nf

d

d

d

d

1

2

2

12

21

1 )(

)()()(

Cross section calculation

Where:

- dp elastic scattering cross section

ε - efficiencies

f – luminosity scaling factor (we know from HD run)

Use data from separate D2 and H2 runs

Efficiency (<90%) d+p d+d

Energy cut 0.79

Notches(φ) 0.865 0.73

Silicon gaps (Ө) 0.63(small Ө) - 0.31 (large Ө)

Others:

coplanarity

Scintillator PID cuts

Silicon PID cuts

Systematic errors: d+d notch 18%

d+d tail 50%

“other” ~10%

TOTAL 54%

)( 22

dd dp

Summary

dddd

pdpd We analyzed:

pd d,dp d,d

We obtained:

Py, Pyy

Normalization factor

iT11, T22, T20, σ(Θ)

Calculation by A. Fonseca

pd d,dHDd

dpD

dpH

dpHD

ddD

ddH

ddHD

22

22

bNaNN

bNaNN

Trigger dd:

Trigger dp:

Trigger dp

= a + b

= a + b

Trigger dd