1. Atom trapping and Recoil Ion Spectrometry for  -decay (and other BSM) studies H.W. Wilschut, KVI, Groningen Or why it is easier to measure things standing still

2. Initial perspective using  -decay for new physics searches “To move correlation measurements into the 10 -3 precision (and beyond) it is essential to obtain correlations differentiated in angle and momentum”

3. The role of trapping The trap sample: isotope (isomer) selective spin manipulation point source, no substrate recoil ion momentum spectrometry Ideal environment for precision experiments Also for APNC, edm… Or why it is easier to measure things standing still

4. Outline Which isotopes can we use when atom trapping Which are being pursued in  -decay /status Need to capture and detect Differentiated measurements (and why are they difficult) Some odd ends

5. Which particles are useful? Have chosen to use isotopes in the searches for new physics (but need to keep an eye on other searches) Measure “forbidden” decays (here:  -decay where particles dare not go): “short-lived” Measure “forbidden” moments (APNC, edm): “long-lived”

6. There are only a few….. ? ? There was not much to choose in Cs isotopes …..

7. e.g. Cs isotopes A=114 to 148 There are plenty…..

8. To study  -decay need to collect and observe: # candidates decrease

9. Which atoms can be trapped KVI RIMS  Trace analysis Next on menu Advantage clear for EDM and APNC but for  -decay? Of course you can try ion trapping instead but we can discuss that…

10. For  -decay light isotopes relevant, atomic trapping covers a large part of the chart, still most are useless  -decay

11. Correlations in  -decay Correlation factors a…R connected by underlying theory And with observations outside nuclear  -decay Which correlation most potential? (help!) Identified D (TRV) as most potential (but willing to change) In any case: must learn the trade with “a”: ignore spin degrees of freedom

12. Expression for ½ +  ½ + transitions No FSI D=0 if all formfactors are real The possible size of D and the effect of the FSI (Theory group KVI - masters thesis Marc van Veenhuizen) finite D due to weak magnetism

13. Comparison of FSI and TRV g=-0.99 + 0.0005i Different momentum dependence at < 10 -4 level similar results for 3/2 +  3/2 + effect negligable on a, A and B

14. But first: Inclusive observables Recoil distribution Impact of  - on recoil Fermi Gamow-Teller Recoil e Vector Recoil e Scalar

15. Best measurement for a Fermi Adelberger et al. PRL83(99)1299 32 Ar(0 + )  32 Cl(0 + ) + e + + ; 32 Cl  31 S + p S V line shape exp a F =0.9989(52)(39) 10 7 cts Higher order corrections folded in: not measured Improved mass measurements made: waiting for new folding

16. Learning from atom trap measurements on “a” TRIUMF (Behr et al.): 38 K m (0 +  0 + ) a F =0.992(8)(5) promised:?(3)(3) making progress in polarization 36 K(2 + ), 37 K(3/2 + ) (A, towards D). LANL (Vieira et al.): 82 Rb TOP for A, halted? LBL: 21 Na (3/2 +  3/2 + ) a= 0.524±0.005 syst (+ a problem we can solve) tried 19 Ne (no success) will try FORT for 21 Na Ion trap methods: Paul-trap 6 He (a GT ) and WITCH project. KVI: first start with 21 Na

17. Search and analysis in the early 60’s: 0 -  0 + (first-forbidden decays) based on  polarization and shape factor using heavy nuclei. Lightest nuclei 0 -  0 + are 50 K(?) and 90 Rb (37%) & 92 Rb(94%) How about recoil spectra/ correlations? S Scalar P Pseudo Scalar ??? V Vector (G V ) A Axial Vector (G A ) T Tensor Intermezzo Structure of  -decay is V - A “beyond” to be found from S, P or T But P not possible? Will it get us anywhere?

18. TRI  P - Trapped Radioactive Isotopes:  -laboratories for fundamental Physics TRI  P Beyond the Standard Model TeV Physics EDM/  -decay Ion Catcher RFQ Cooler MOT Nuclear Physics Atomic Physics Particle Physics Production Target Magnetic Separator MeVmeVkeVeVneV AGOR cyclotron

19. Dispersive plane Achromatic focus QD AGOR beam T1 Traps DD TRI  P 21 Na production @ TRI  P KVI Detector B  = p/q  v A/Z  E  A 2 TOF  A/Z TOF  21 Na 16 O Observed production rate in the reaction p( 21 Ne, 21 Na)n 50 Hz/pnA/mg[H 2 ]/cm 2

20. V 0 (keV) Principle idea MOT + RIMS MeV  detector MCP -V 0 +V 0 0 SM Not SM TOF  E // very efficient X,Y  E  for charged recoils start stop

21. MOTRIMS (KVI atomic physics, S. Knoop) O 6+ + Na  O 5+ (n) + Na + ion beam n = 5 6 7 8 NaO 5+ 8 7 6 n=5 resolution 6 m/s !

22. Two realizations Setup at TRIUMF (Behr et al.) for 38m K (t 1/2 =0.93 s; 0 +  0 + ) 21 Na production Cooling stage Trapping & detection Freedman/Vetter setup LBL 21 Na N. Scielzo thesis++

23.  + versus  -  + decay  recoil neutral (80%) 21 Na (11p + 10n)  21 Ne (10p + 11n) +  + 78% 19% 3% 0.3%  - decay  recoil 1 + : 80%  no good? (3  branch) 25 Na (11p + 14n)  25 Mg (12p + 13n) +  - Neutrals not efficient MCP inefficient and tricky  + momentum  q-dist 2  background (511 keV) systematic errors: 1.RIMS related 41% 2.Unwanted decays (off walls etc.) 26% 3.  detection 24%

24. 3/2 + 21 Na 22.47s 5/2 + 9 ps 0.3505 A problem that can be solved Scielzo et al. measured for 21 Na a=0.5243 ± 0.0066 ± 0.0049 ± 0.0041     (deviating 2.3  )stat. 6  10 5 evt’s systematic branching 3/2 + 21 Ne ++ 5.1±0.2 % remeasure

25. Conclusions Atomic trapping a starting point for various studies RIMS is essential for  -decay studies Trapping has its specific problems (  - /  + ) Polarization (D, A) being developed TRI  P starts working…. but long way to go