The DRIFT experiment Recent results from the DRIFTIId

The DRIFT experiment: Recent results from the DRIFT-IId detector James Battat Wellesley College [for the DRIFT collaboration] CYGNUS 2015 @ Oxy 2015 June 2 nd

Overview of talk • CS 2 as negative ion drift Martoff et al. NIMA, 400 (2000); Snowden-Ifft, Martoff, Burwell, PRD 61 10 (2000). • DRIFT’s successful quest to reduce backgrounds Currently operating background-free Snowden-Ifft, Rev. Sci. Instrum. 85 013303 (2014) [DRIFT collab. ] Battat et al. , JINST, 9 P 11004 (2014) [DRIFT collab. ] Battat et al. , NIMA 794 (2015) • 2014 SD-proton limit: 1 pb at 100 Ge. V/c 2. [DRIFT Collab. ], Battat et al. , ar. Xiv: 1410. 7821, submitted to Phys. of Dark Universe Steve Sadler, Ph. D Thesis Sheffield University, 2014 • Additional improvements give preliminary result of σSD-p~0. 3 pb 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 1

Directional Recoil Identification From Tracks Occidental College Dan Snowden-Ifft - PI Jean-Luc Gauvreau Chuck Oravec Alex Lumnah Nick Waldram The University of Edinburgh Alex Murphy – PI 6/2/2015 Sheffield University Neil Spooner – PI Ed Daw – PI Matt Robinson Dan Walker Steve Sadler Andrew Scarff Anthony Ezeribe Frederic Mouton Trevor Gamble University of New Mexico Dinesh Loomba - PI Michael Gold – PI John Matthews - PI Eric Lee Eric Miller Nguyen Phan Randy Lafler Joshua Martin Wellesley College James Battat – PI University of Hawaii Sven Vahsen – PI Tom Thorpe James Battat, Wellesley College, CYGNUS 2015 Josh Murillo Colorado State University John Harton – PI Jeff Brack Dave Warner Alexei Dorofeev Fred Shuckman II Boulby Laboratory Sean Paling – PI Emma Meehan Louise Yeoman Chris Toth 2

DRIFT in Boulby: 2805 m. w. e. Operated by the UK’s Science & Technology Facilities Council (STFC) in partnership with the mine operators ICL Mei & Hime [astro-ph/0512125] For scope of work at Boulby, see talk by Chris Toth, Thursday 14: 30. 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 3

Negative ion formation W IM P Nucle a Reco r il W e- -eee- e e-e Mean electron capture distance is a few hundred microns E-field Drift direction 6/2/2015 Martoff et al. , NIMA, 440 (2000) Snowden-Ifft, et al. , PRD, 61, 101301 (2000) Snowden-Ifft & Gauvreau, Rev. Sci. Instrum. , 84, James Battat, Wellesley College, 053304 (2013) CYGNUS 2015 4

Transport of CS 2 negative ions • Diffusion is ~ thermal (both transverse and longitudinal) low diffusion increases active volume per readout area • Drift speeds are ~5 cm/ms or ~20 us/mm Snowden-Ifft & Gauvreau, Rev. Sci. Instrum. , 84, 053304 (2013) James Battat, Wellesley College, [ar. Xiv: 1301. 7145 v 2] 6/2/2015 CYGNUS 2015 5

Negative ion gas mixtures • Ar: CH 4: CS 2, Xe: CS 2, CF 4: CS 2 , CF 4: O 2: CS 2… Martoff et al. , NIMA 440 (2000) Lightfoot et al. , Astropart. Phys. 27 (2007) • CS 2 is not the only negative ion gas Nitromethane (CH 3 NO 2) SF 6 6/2/2015 [Martoff et al. , NIMA 598 (2009)] [see Nguyen Phan’s talk Thr. , 13: 30] James Battat, Wellesley College, CYGNUS 2015 6

Some DRIFT detector nomenclature DRIFT-IId 0. 8 m 3 Demonstrated 2 pb sensitivity in 2012 Has since been upgraded and is currently running background-free (texturized thin-film cathode, and 3 D fiducialization) DRIFT-IIe 0. 8 m 3 engineering prototype for DRIFTIII Currently at Occidental College. D-HD DRIFT-HD 0. 25 m 3 high spatial-resolution (Proposed) DRIFT-III 24 m 3 (Proposed) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 7

DRIFT-IId geometry 900 Dimensions in mm Fiducial volume is 0. 8 m 3 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 8 Image from Burgos et al. , NIMA 584 (2008)

DRIFT-IId geometry MWPC: 3 wire planes 1 cm gaps 552 wires 448 fid. 2 mm pitch z=0 Grid wires -2. 8 k. V 100 um diam. 900 Anode wires Grounded 20 um diameter 6/2/2015 z=50 cm Left MWPC James Battat, Wellesley College, CYGNUS 2015 Cathod e -32 k. V Right MWPC 9

DRIFT readout Heavy grouping, low channel count 100% spatial ambiguity (8 -wire = 16 mm periodicity) … 448 anode wires … 6/2/2015 Image from M. Pipe Ph. D Thesis, U. Sheffield, 2011 James Battat, Wellesley College, CYGNUS 2015 10

The War on Backgrounds • 2005: 500 evt/day • 2012: 130 evt/day (material selection) • 2014: 1 evt/day (0. 9 um thin-film cathode) • 2014: 0 evt/day (z-fiducialization) See talk by Eric Miller, Wed. , 13: 30 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 11

z-fiducialization: differential drift speeds MWPC Drift direction 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 Proportionality constant can be measured for various gas mixtures, or calibrated in-situ. 12

z-fiducialization: limitations Data from an R&D vessel, not DRIFT-IId Po 210 Snowden-Ifft, Rev. Sci. Instrum. 85 013303 (2014). 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 13

DRIFT-IId: some numbers • CS 2: CF 4: O 2 30: 1 Torr • Mass of F: 40 g/0. 8 m 3 C: 18 g/0. 8 m 3 S: 96 g/0. 8 m 3 • 30 ke. Vr F recoil = 1 mm range • CS 2 - drift speed ~5 cm/ms. (10 ms for full 50 cm drift, 20 us/mm) • Gas gain ~1000 • Source-free running for 46. 3 live days Fe-55 calibrations every 6 hours Cf-252 neutron calibration 5 runs, 3. 2 live days 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 14

Events in DRIFT • Any anode channel > 30 m. V triggers readout of all channels. • Raw trigger rate ~ 1 Hz • Adverse effect on Ethresh 50% efficiency at ~50 ke. Vr F • Improved trigger implemented 50% eff. at ~20 ke. Vr F RG = Right grid (1 – 8 and sum) RVG = Right veto (grid) RVA = Right veto (anode) RA = Right anode (1 – 8 and sum) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 15

Events in DRIFT Right MWPC, Anode #7 Line 6/2/2015 RG = Right grid RVG = Right veto (grid) RVA = Right veto (anode) RA = Right Wellesley anode James Battat, College, CYGNUS 2015 16

Data processing Raw triggers Noise filtering, undershoot removal, saturation cut Signal conditionin g Stage I cuts Bkg rejection E recon z recon 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 17

Data processing Raw triggers Signal conditionin g Stage I cuts • • • xy-fiducialization (veto above threshold) Temporal ROI cut (+/- 700 us) Cathode-crossing events (hits in both TPCs) Multiples (non-contiguous hits) Maximum range (all 8 anode channels Ry >16 mm) • Impulse charge deposition (risetime < 3 us) Bkg rejection E recon z recon 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 18

Data processing Raw triggers Signal conditionin g • Ratio of ionization in Min. Car. region to total ROI • Require comparable ionization on anodes and grid Stage I cuts Bkg rejection E recon z recon 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 19

Data processing Raw triggers Signal conditionin g Stage I cuts Bkg rejection • Compute event energy in m. V*us Sum up waveform integrals for all anode channels above an analysis threshold (9 m. V). • Convert to ke. Vee (equivalently NIPs) m. V*us to ke. Vee via 55 Fe calibration (every 6 h, stable to 4%) ke. Vee to NIPs via W=25. 2 e. V * • Convert to ke. Vr Use [Hitachi 2008] prediction. For CS 2: CF 4 quenching measurements, see talks by Eric Miller (Wed. , 13: 30) and Alex Lumnah (Thr. , 14: 00) E recon z recon * W not yet measured for CS 2: CF 4: O 2 mixture, but expect ~1% change from CS 2: CF 4, which has been measured [P&S 2009]. [Hitachi 2008] Hitachi, Radiat. Phys. Chem. 77 (10– 12) (2008) [P&S 2009] Pushkin & Snowden-Ifft, NIMA 606 (2009) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 20

Data processing Require 3 peaks, evenly spaced Raw triggers Signal conditionin g Stage I cuts Bkg rejection E recon z recon dt ~ 150 us (S to I) Z ~ (0. 24 cm/us)*dt ~ 36 cm I peak width is ~ 50 us, so z-recon gets hard below z ~10 cm. 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 21

Cathode RPR/LEAs 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 22

Detection efficiency post-Stage I 50% at ~50 ke. V 50% at ~20 ke. V 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 23

Nuclear Recoil Detection Efficiency Map 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 24

DRIFT’s 2015 SD-proton limit DMTPC (2011) NEWAGE (2015) DRIFT (2012) DRIFT (2015) PICO (2015) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 25

Room for improvement • Improved trigger to capture lower energy events Factor of ~2 in threshold • Improve efficiency at high-z z-reconstruction does not rely on S-peak • Gas circulation to maintain O 2 partial pressure Minority peak ionization is strongly O 2 dependent. • Can we do better at low z (z<10 cm)? • Will new backgrounds appear? 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 26

Efficiency Map (prelim. ) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 27

Preliminary analysis shows 0. 3 pb y r a n i m i l e r P DRIFT (2015 b, preliminary) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 28

Events passing cuts 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 29

Summary • A 1 pb limit is on the ar. Xiv: 1410. 7821 • Since then, upgrades to the detector and analysis have improved the reach by another factor of ~3 to give σSD-p~ 0. 3 pb • Have ~65 live-days in-hand (and counting). 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 30

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Quenching 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 32

6/2/2015 James Battat, Wellesley College, CYGNUS 2015 33

DAQ has a high-pass filter • To get rid of 50 Hz mains noise. (1/50 Hz = 20 ms = 20000 us) • For C=2200 p. F, R=50 Ohm, tau=RC= 0. 1 us • (see M. Pipe’s thesis, page 61). 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 34

Waveform conditioning • Frequency filtering – 55 k. Hz noise notch filter (HV supply) – 50 Hz line noise (subtract sine fit) • Undershoot correction – Shaping electronics (4 us shaping time) cause undershoot • Analysis threshold is 9 m. V (trigger threshold was 30 m. V). What is waveform baseline RMS? 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 35

DRIFT readout 1 … 6/2/2015 Anode wires 9 17 25 James Battat, Wellesley College, CYGNUS 2015 36

MWPC 3 planes 1 cm gaps Grid 512 wires 100 um diameter Anode 512 wires 20 um diameter 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 37

Passes cuts on: • xy fiducialization • Risetime • Multiples Fails cut because: • Cathode-crossing • Range too long (all anode lines hit • ROI cut 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 • RATE OF ALPHAS? ? ? 38

Background rejection Spark cut Ratio of ionization in minority carriers region to total ROI ionization “Ringer” cut Require comparable ionization on anodes and grid 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 39

Stage I cuts • • • xy-fiducialization (veto above threshold) Temporal ROI cut (+/- 700 us) Cathode-crossing events (hits in both TPCs) Multiples (non-contiguous hits) Maximum range (all 8 anode channels Ry >16 mm) • Impulse charge deposition (risetime < 3 us) 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 40

Energy reconstruction • Compute event energy in m. V*us Sum up waveform integrals for all anode channels above an analysis threshold (9 m. V). • Convert to NIPs (equivalently ke. Vee) Calibration constant derived from frequent 55 Fe calibrations studies – stable to ~4% over experiment. Also: W=25. 2 e. V * • Convert to ke. Vr Use [Hitachi 2008] prediction. For CS 2: CF 4 quenching measurements, see talks by Dinesh Loomba (DAY, TIME) and Alex Lumnah (DAY, TIME) * W not yet measured for CS 2: CF 4: O 2 mixture, but expect ~1% change from CS 2: CF 4, which has been measured [P&S 2009] [Hitch 2008] 6/2/2015 Pushkin & Snowden-Ifft, NIMA 606, 2009 Hitachi, Radiat. Phys. Chem. 77 (10– 12) (2008) James Battat, Wellesley College, CYGNUS 2015 41

Transport of CS 2 negative ions • Diffusion is ~ thermal (both transverse and longitudinal) • Drift speeds are ~5 cm/ms aka ~20 us/mm “low-field” approximation hold even at 580 V/cm Snowden-Ifft & Gauvreau, Rev. Sci. Instrum. , 84, 053304 (2013) James Battat, Wellesley College, [ar. Xiv: 1301. 7145 v 2] 6/2/2015 CYGNUS 2015 42

DRIFT-IId geometry MWPC 3 planes 1 cm gaps Grid 552 wires, 448 fid. 2 mm pitch 100 um diameter 900 Anode 552 wires, 448 fid. 2 mm pitch 20 um diameter z=0 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 z=50 cm z=0 43

TO DO • • Dates for new limit run (July to October 2014) Verify gas gain = 1000 Why is 55 -day efficiency so high at z~50 cm? (used to be 10 -30%, is now 25 -90%)? Capacitance of ONE anode wire? Cap. when grouping 56 of them into one preamp? • • Rates of events that get cut? ? ? What is alpha rate? ~1/4 Hz. • Why are so many anode wires needed for the veto? (43 on each side, plus 9 guard wires on each side). What is new triggering scheme (integral? ) 18 us boxcar averaging for trigger. New threshold is 15 m. V. 50% at 500 NIPs Validation that waveform filtering (notch filter, 50 Hz, undershoot removal) preserve event quantities like energy, head tail, etc. ? Why integrate waveforms (vs. take amplitude) for NIPs? Isn’t it already integrated by electronics? Check collaboration slide Fix “Boulby Mine” slide. Fe 55 252 e- • • • 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 44

Events passing cuts 6/2/2015 James Battat, Wellesley College, CYGNUS 2015 45