Production and Storage of Polarized H2, D2 and HD Molecules by Ralf Engels JCHP / Institut für Kernphysik, FZ Jülich 10.09.2018 Dr. Ralf Engels 25.06.2009

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

PIT @ ANKE/COSY Main parts of a PIT: Atomic Beam Source Target gas hydrogen or deuterium H beam intensity (2 hyperfine states) 8.2 . 1016 atoms / s Beam size at the interaction point σ = 2.85 ± 0.42 mm Polarization for hydrogen atoms PZ = 0.89 ± 0.01 (HFS 1) PZ = -0.96 ± 0.01 (HFS 3) Lamb-Shift Polarimeter Storage Cell M. Mikirtychyants et al.; NIM A 721 (0) 83 (2013) Dr. Ralf Engels 25.06.2009

Pm = ½ Pa Polarized H2 Molecules Pm β= Pa Measurements from NIKHEF, IUCF, HERMES show that recombined molecules retain fraction of initial nuclear polarization of atoms! Pm Pa β= Pm = ½ Pa The HERMES Collaboration; Eur. Phys. J. D 29, 21–26 (2004) DOI: 10.1140/epjd/e2004-00023-5

Pm = 0.5 Pa Polarized H2 Molecules Eley-Rideal Mechanism Is there a way to increase Pm P (surface material, T, B etc)?

Pol. Molecules: The experimental setup ISTC Project # 1861 PNPI, FZJ, Uni. Cologne DFG Project: 436 RUS 113/977/0-1 H2+, D2+ HD+, H3+ p, d

The experimental Setup The Lamb-shift Polarimeter mI = +1/2 N+1/2 – N-1/2 N+1/2 + N-1/2 P= mI = -1/2 R. Engels et al., Rev. Sci. Instr. 74 4607 (2003) R. Engels et al., Rev. Sci. Instr. 85 103505 (2014)

The experimental setup The Lamb-shift Polarimeter H2 H2+ H2+ H2S H2S (α1) H+ H+ H2S H2S (α1) Efficiency ∙ 2 ∙ 0.025 = 5 ∙ 10-12 ∙ 0.2 = 2 ∙ 10-11 See talk by L. Huxold at 10th of September (6 pm, Room A9)  

( ) Pm(B,n) = Pm0 P(B,n) = Pm · e Polarized H2 Molecules Polarization losses of the molecules due to: spin-spin (I↔I) interactions of the nucleons Interaction of the nuclear spins I with the rotational magnetic moment J Interaction with the external magnetic field B … Nuclear Polarization of Hydrogen Molecules from Recombination of Polarized Atoms T.Wise et al., Phys. Rev. Lett. 87, 042701 (2001). n ≈ 1000 Naive Model: P(B,n) = Pm · e - n ( ) 2 Bc B 1 1+(Bc/B)2 ∙ n/ln 2 Pm(B,n) = Pm0 with: Bc = 5.4 mT, n ≡ average amount of wall colissions

Theory

p Experimental results Measurements on Fomblin Oil (Perfluoropolyether PFPE) HFS 3 TCell = 100 K Pm = -0.87 Pm = - 0.81 ± 0.02 n = 174 ± 19 c = 0.993 ± 0.005 p H 2 + Pm = - 0.84 ± 0.02 n = 277 ± 31 R. Engels et al., Phys. Rev. Lett. 115 113007 (2015) Dr. Ralf Engels 25.06.2009

Recombination on Fomblin (?) . . . . Bext . F F F F C - O - C - O - C O --C Fused Quarz Dr. Ralf Engels 25.06.2009

HD Molecules Pz (D) = -0.3 Pzz (D) = 0.12 Pz (H) = -0.21 D H H (Surface: Gold / T = 80 K / B = 0.528 T / E = 2 keV) Pz (D) = -0.3 Pzz (D) = 0.12 Pz (H) = -0.21 H D H

HD Molecules (Surface: Gold / T = 80 K / B = 0.528 T / E = 2 keV) H D H

HD Molecules Signal of the Photomultiplier [a.u.] Surface: Fomblin on Fused Quarz T = 80 K / B = 0.528 T / E = 0.3 keV Pz (H) = - 0.77 Pz (D) = - 0.79 Pzz (D) = + 0.69 Signal of the Photomultiplier [a.u.]

HD Molecules

H H D D Brot Brot H D Brot Bc ~ Brot / r3 Bc (H2) Bc (HD) = 2.4 = 3.4 HD Molecules H H D D Brot Brot Naive Approximation: Distance Brot <-> H increased by 1/3 Distance Brot <-> D decreased by 1/3 Bc ~ Brot / r3 2/3 1/3 H D Brot Bc (H2) Bc (HD) = 2.4 = 3.4

Experimental Results for Mass 3 Pz = - 0.23 Preliminary

Production of polarized D2 and HD ice possible? T= 3-10K Cold Head D2 ice Polarization Measurement: NMR – Sensor Dr. Ralf Engels 25.06.2009

Conclusion We can measure: the polarization of atoms and molecules in a storage cell. the recombination of hydrogen/deuterium atoms on different surfaces and for different HFS. If Bc is known: the number of wall collisions of the molecules in the cell. Pay attention: Other depolarizing effects, e.g. magnetic impurities on the surface or charged islands on isolating surfaces, will increase the Bc.

Conclusion We can produce polarized H2, D2 and HD molecules with large vector- and tensor-polarization (~ 0.8) in many spin combinations. For what it is usefull? 1.) More dense polarized targets. 2.) Spectroscopy of the molecules or molecular ions (Contact with the University of Düsseldorf). 3.) New insights in chemical reactions / surface physics. 4.) Polarized fuel to increase the energy output of Fusion reactors. -> see talk on Wednesday, 2:30 pm 5.) Polarized targets for laser acceleration. -> see talk by M. Büscher on Wednesday, 5:05 pm 6.) EDM measurements ? 7.) An option to produce polarized molecules for medical application ?