1. MuD project: m + d  n + n + n
Peter Kammel, UIUC
Outline
Physics Motivation Experimental Concept
fundamental EW 2-body reactions
high impact for fundamental astrophysics reactions
10x precision improvement feasible by MuCap techniques

2. Relevant Physics Ld n d W m- nm En (MeV) pEFT Pn= 0 MeV/c pn(MeV/c) 1050 60 70 80
9 0
1 00 20 30 40 QF
FSI
MEC>IA
En (MeV)
pEFT
pn(MeV/c)
Pn= 0 MeV/c Ld
two md hfs states: quartet  and doublet 
overall nucleon FF dependence similar to mp, dLd=1%  dgP=6%
2-N physics important (deuterium wavefunction, ann, …)
MEC’s significant
space-like (small qnn): dominantly D isobar current EFT: L1A (isovector, axial) 4N vertex
time-like (large qnn): MEC 10x IA contribution, higher sensitivity to gp ?, (neutrino mass, historic) mD

3. pEFT: Class of axial current reactions related by single unknown parameter L1A
basic solar fusion reaction
p + p  d + e+ + 
key reactions for solar neutrino detection and supernova neutrino
 + d  p + p + e
 + d  p + n + 
short distance, axial two body currents, ab-inito pEFT(NNLO) vs. SNPA vs. EFT*
gpND
MEC EFT
L1A
md capture close terrestrial analogue
soft enough ?
precision measurement possible ? n p d d n p W W e+ m- nm ne mD

4. L1A information Process L1A (fm3) Reference CC, NC, ES 4.0  6.3
From H. Robertson talk
Process
L1A (fm3)
Reference
CC, NC, ES
4.0  6.3
Chen et al., PRC 67, (2003), nucl-th/
Reactor antineutrinos
3.6  4.6
Butler et al. nucl-th/
Tritium b decay
4.2  0.1
Schiavilla et al. PRC 58, 1263 (1998); Park et al. nucl-th/ & nucl-th/ ; Ando et al. nucl-th/
Solar pp reaction
4.8  5.9
Brown et al. nucl-th/
Potential model
4.0
Nakamura et al. NP A707, 561 (2002)
mHe ? md
1.5 ?
Kammel, Chen, et al., nucl-ex/ , this talk
Would be by far best constraint from basic 2-body system ! mD

5. m+d theory results Ld (s-1) total IA calculations
Ando et al (2002): EFT* with tritium decay constraint estimate of uncertainties comment sensitivity to cut-off 1 s-1 no 3N uncertainty gP 1 assumes PCAC value higher order 1 L> total ~1% ann ~3% ??, rad. corr. need calculations
2 body currents 6.5%, High qnn contribution negligible  % experiment on Ld measures L1A to 15-20%
Chen (private comm): pEFT, q < 10MeV/c, higher oder ?

6. m+d experiments challenges: md () + d md () + d ddm  n + m3He
x3, because really statistical mix
date
author F
T(K) Cd
Ld(s-1) s
1965
Wang
et al. 1 18
0.0032
365 96
1973
Bertin
0.013
239
0.05
445 60
1986
Bardin
470 29
1989
Cargnelli et al.
0.04 40
409
Ld (s-1)
theory
experiments

7. update m3He capture rateIA
IA+MEC
theory
Marcucci 02 gpND constraint by tritium decay
Ho,Fearing 01
Congleton,Truhlik 96 Congleton, Fearing 93 EPM Congleton, Fearing 93
time
experiment
Ackerbauer 98
Lst (s-1)

8. Differential observables
n-n correlation at small qnn: ann measurement, current exp: ann=18.9 (4) fm
dL/dEn
Lq/Ld~2.5% measurement
Asymmetry and mSR

9. Summary physics motivation
precision measurement of total md capture rate to 1% provides
first precise measurement of charged-current reaction in 2N system
first precise 2N experimental information relevant for absolute solar neutrino cross sections and flux.
comparison of EFT/SNPA approach for space-like axial two-body current and 2N vs 3N constraints.
ann information ? (needs study)
systematic measurement of md capture Dalitz Plot provides
information on time-like axial two-body currents, p+p+p puzzle
reduced rate L’, accessible to pEFT
complementary gP sensitivity, if MECs sufficiently under control (needs study)
first measurement of md capture asymmetry and hfs effects provides
complementary gp info (needs study)

10. 1% precision experiment possible?
measurement of absolute rate 3 % (MuD 0) ?
Basic lifetime method, present TPC
measurement of absolute rate 1 % (MuD I)
Kinetics requires optimized target conditions 80K, 5% density, new TPC arrangement
mSR effects
isotopic purity much simpler
measure full DP if sufficient physics motivation (MuD II) Neutron detector array
Kinematics determined by angle and dt
liquid target?
Goals:
determine reduced rate L’ by subtracting Dalitz Plot (En>10MeV) with 5% prec.
gP, time-like MECs
<1% precision seems possible according to preliminary feasibility study !
md()
5% LD2 80 K
md()
m3He 20
En (MeV)
En (MeV)
L’~90% of intensity

11. kinetics

12. kinetics S(y)=DLd/Ld / Dy/y
1% LD2 300 K
5% LD2 80 K
md()
md()
md()
md()
m3He
m3He
Sensitivity to parameter y
S(y)=DLd/Ld / Dy/y
f=1%, T=300 systematic errors ~1% f=5%, T= corrections <3%, systematic errors <0.1%

13. Exp. concept
=175
=150
=155
=160
=165
=170
=145