Mitglied der Helmholtz-Gemeinschaft on the LEAP conference Polarized Hydrogen/Deuterium Molecules A new Option for Polarized Targets? by Ralf Engels JCHP / Institut für Kernphysik, FZ Jülich

2 internal experiments – with the circulating beam external experiments – with the extracted beam p, p, d, d with momenta up to 3.7 GeV/c

3 ANKE/COSY Main parts of a PIT: Atomic Beam Source Target gas hydrogen or deuterium H beam intensity (2 hyperfine states) atoms / s Beam size at the interaction point σ = 2.85 ± 0.42 mm Polarization for hydrogen atoms P Z = 0.89 ± 0.01 (HFS 1) P Z = ± 0.01 (HFS 3) Lamb-Shift Polarimeter Storage Cell M. Mikirtychyants et al.; NIM A 721 (0) 83 (2013)

4 ABS and Lamb-shift polarimeter 6-pole magnet 6-pole magnet rf-transition

5 Polarized H 2 Molecules Is there a way to increase P m P (surface material, T, B etc)? P m = 0.5 P a Eley-Rideal Mechanism

6 Polarized H 2 Molecules o-H 2 ↔ p-H 2 : ΔE = kJ/mol J = 1, 3, 5 J = 0, 2, 4 T = 0 K:0:4 T= 300 K:3:1

7 Polarized H 2 Molecules -

8 Measurements from NIKHEF, IUCF, HERMES show that recombined molecules retain a fraction of initial nuclear polarization of atoms! Polarized H 2 Molecules The HERMES Collaboration; Eur. Phys. J. D 29, 21–26 (2004) DOI: /epjd/e

9 Theory A.Abragam: The Principles of Nuclear Magnetism Hamiltonian to describe the nuclear relaxation of a H 2 molecules H = ω I ( I 1 z + I 2 z ) + ω J J z + ω‘ (I 1 + I 2 )·J + ω‘‘ { I 1 · I 2 – 3(I 1 · n)(I 2 · n)} I 1 and I 2 are the spins of the two protons I 1 + I 2 = I J is the rotational angular momentum of the molecule ω I = - γ I H 0 is the proton Lamor frequency in the applied field H 0 ω J = - γ J H 0 is the Lamor frequency of the rotational magnetic moment of the H 2 ω‘ = - γ I H‘ is the strength of the coupling between the magnetic moment of the protons and the magnetic field produced at their positions by the rotation of the molecule ( H‘ = 2.7 mT) ω‘‘ = 2 γ I H‘‘ = γ I 2 ħ/ b 3 is the strength of the dipolar coupling between the protons, b is their distance, and n is the unit vector b/b (H‘‘ = 3.4 mT). B c (H z ) ≠ B c (D z ) ≠ B c (D zz )

10 Nuclear Polarization of Hydrogen Molecules from Recombination of Polarized Atoms T.Wise et al., Phys. Rev. Lett. 87, (2001). Polarized H 2 Molecules Spin Relaxation of H 2 /D 2 Molecules A. Abragam: The Principles of Nuclear Magnetism (1961) The polarization losses during wall collision depend on: -Nuclear Spin I -Polarization P m -Temperature -Magnetic field in the cell P (B,n) = P m · e - n ( ) 2 BcBc B n ≈ 1000 Polarization losses of the molecules B c = 5.4 mT

11  Recombination of polarized atoms into molecules  Conversion of polarized atoms and molecules into ions  Separation of protons and H 2 by energy with the Wienfilter  Measurement of proton and H 2 polarization in LSP polarized cell wall B ~ 1T The idea + +

12 The Setup ISTC Project # 1861 PNPI, FZJ, Uni. Cologne DFG Project: 436 RUS 113/977/0-1

13 + H 2 + e → H + 2e + … H 2 + e → H 2 + 2e The Ionization Processes + (E e = 150 eV: σ = 0.46 · cm 2 ) (E e = 150 eV: σ = 0.88 · cm 2 ) (E e = 150 eV: σ = · cm 2 ) ( H + e → H + 2e +

14 Recombination

15 Experimental results Mass separation with the Wienfilter F el = F B E q = - q v B

16 Experimental results Wienfilter function of the protons in the LSP E kin (p) = 1 keV

17 Experimental results Wienfilter function of the H 2 ions in the LSP +

18 Experimental results How are the polarized H 2S produced from H 2 ? + 2-step process (Stripping at the Cs + H 2S production) 1-step process: Direct production: H 2 + Cs → H 2S + Cs + … + Cross section: σ(p→H 2S ) ≈ 35·σ(H 2 →H 2S ) +

19 Theory

20 Theory

21 Theory

22 See Talk by A. Nass on Friday Experimental results Protons:

Experimental results Polarization of the Protons (HFS 1, E p = 4 keV, Gold Surface, B=0.28 T)

24 Experimental results Measurements on Fused Quartz Glass in the first hours P m = 66 % of the original atomic Polarization T Cell = 100 K

25 Experimental results Measurements on Fused Quartz Glass after several days T Cell = 100 K P m = ± n = 368 ± 23 P a = 0.85 ± 0.01 n = 363 ± 29 c = ± 0.002

26 Experimental results Measurements on Fused Quartz Glass after several days T Cell = 50 K P m = ± n = 321 ± 23 P a = 0.46 ± 0.21 n = 351 ± 104 c = 0.98 ± 0.02 No real changes between 50 and 100 K

27 Experimental results Measurements on Fomblin Oil (Perfluorpolyether PFPE) HFS 3 T Cell = 100 K H 2 : P m = ± 0.02 n = 277 ± 31 Protons: P m = ± 0.02 n = 174 ± 19 c = ±

28 Experimental results J.S. Price and W. Haeberli, “Measurement of cell wall depolarization of polarized hydrogen gas targets in a weak magnetic field” Nuclear Instruments and Methods in Physics Research A 349 (1994)

29 Experimental results Measurements on Fomblin Oil (Perfluorpolyether PFPE) HFS 3: Next attempt T Cell = 100 K H 2 : P m = ± 0.02 n = 140 ± 60 Protons: P m = ± 0.02 n = 429 ± 133 c = ± P a = ±

30 Experimental results Measurements on Fomblin Oil (Perfluorpolyether PFPE) HFS 2+3: Next attempt T Cell = 100 K H 2 : P m = ± 0.02 n = 235 ± 29 Protons: P m = ± 0.02 n = 522 ± 87 c = 0.88 ± 0.02 P a = ±

31 Experimental results Measurements on Fomblin Oil (Perfluorpolyether PFPE) Measurement on the 3. day Measurement on the 4. day T=100 K (only H 2 ) +

32 Experimental results Measurements on Fomblin Oil (Perfluorpolyether PFPE) HFS 3 HFS 2+3 B cell = 0.4 T, H 2 only +

33 Experimental results Very first results on water (Fomblin): p H2H2 + Very Preliminary HFS3

34 Experimental results Very first results on water (Gold): T cell = 100 K -0,44 P m = 0.28 ±0.01 n = 399 ± 20 P m = ±0.01 n = 421 ± 33 P m = ±0.01 n = 773 ± 27

35 Experimental results Measurements on Fused Quartz Glass after several days Deuterium: HFS 3+4 (Vector and Tensorpolarized) P m,z = ±0.01 n = 875 ± 96 P m,zz = 0.24 ± 0.03 n = 1210 ± 314 (P a,z = ± 0.01 / P a,zz = ± 0.02) P m,zz = 0.24 ± 0.03 n = 2030 ± 753 c = ± P m,z = ±0.01 n = 894 ± 230 c = ± T Cell = 100 K

36 Conclusion We can measure: -the recombination of hydrogen/deuterium atoms on different surfaces and for different HFS. -the polarization of atoms and molecules in a storage cell. -the number of wall collisions of the molecules in the cell. At least, we can see the difference between „hard“ and „soft“ materials (cos-distribution or cos x -distribution). -the B c for vector- and tensor-polarized Deuterium. -We can increase the target density with recombined molecules. => B c (D z ) = 8 ±1 mT / B c (D zz ) = 11 ±1 mT

37 To-do List -Calculation of B c for vector- and tensor-polarized Deuterium - Additional cryo-catcher between ABS and ISTC-chamber -Measurements on different surfaces: - Aluminium - Teflon - … -More measurements on a water surface (Maybe the surface below has some influence …) -Development of a new openable storage cell for ANKE -Polarized Deuterium Fuel for polarized fusion reactors ( Talk on Monday)