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New DRIFT Results Daniel SnowdenI5 Occidental College for the DRIFT Collabora>on February 18, 2016 Dark MaHer 2016

DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

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Page 1: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

New  DRIFT  Results  

Daniel  Snowden-­‐I5  Occidental  College  

for  the  DRIFT  Collabora>on  February  18,  2016  Dark  MaHer  2016  

Page 2: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Occidental  College  Dan  Snowden-­‐I5  -­‐  PI  

University  of  New  Mexico  

Dinesh  Loomba  -­‐  PI  

Colorado  State  University  

John  Harton  –  PI  

Sheffield  University  Neil  Spooner  –  PI  

 

The  University  of  Edinburgh  

Alex  Murphy  –  PI  

Direc>onal  Recoil  Iden>fica>on  From  Tracks  (DRIFT)  

 Wellesley  College  James  BaHat  –  PI  

 University  of  Hawaii  Sven  Vahsen  –  PI  

Boulby  Mine  Sean  Paling  –  PI  

Page 3: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Introduc>on  to  DRIFT  •  Direc>onal  Detector  (PRD,  61  (2000)  1,  

NIMA,  600  (2009)  417,  AstroPle,  31  (2009)  261)  

•  DRIFT  has  been  opera>ng  in  Boulby  since  2001  

•  DRIFT-­‐I  -­‐>  DRIFT-­‐II  (a-­‐e)  •  DRIFT-­‐IId  volume  =  0.8  m3,  40  Torr  gas  •  50  cm  dri`  region  •  MWPC  readouts  (NIMA,  555  (2005)  173)  •  Nega>ve  CS2  anion  dri`  to  limit  diffusion  

(PRD,  61  (2000)  1)  

•  Phenomenal  Compton  background  rejec>on  (AstroPle,  28  (2007)  409)  

•  Many  gas  mixtures  possible  •  DRIFT-­‐IId  used  a  30-­‐10  Torr  of  CS2-­‐CF4  to  

op>mize  for  spin-­‐dependent  limits,  139  g  target  mass.  

Page 4: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

XKCD  on  Dark  MaHer  Searches  in  Boulby  

Page 5: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Introduc>on  to  DRIFT  •  Direc>onal  Detector  (PRD,  61  (2000)  1,  

NIMA,  600  (2009)  417,  AstroPle,  31  (2009)  261)  

•  DRIFT  has  been  opera>ng  in  Boulby  since  2001  

•  DRIFT-­‐I  -­‐>  DRIFT-­‐II  (a-­‐e)  •  DRIFT-­‐IId  volume  =  0.8  m3,  40  Torr  gas  •  50  cm  dri`  region  •  MWPC  readouts  (NIMA,  555  (2005)  173)  •  Nega>ve  CS2  anion  dri`  to  limit  diffusion  

(PRD,  61  (2000)  1)  

•  Phenomenal  Compton  background  rejec>on  (AstroPle,  28  (2007)  409)  

•  Many  gas  mixtures  possible  •  DRIFT-­‐IId  used  a  30-­‐10  Torr  of  CS2-­‐CF4  to  

op>mize  for  spin-­‐dependent  limits,  139  g  target  mass.  

Ce

ntr

al C

ath

od

e

Rig

ht

MW

PC

Left

MW

PC

E E

Page 6: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

DRIFT-­‐IId  Data  CS2−CF4 Winter 09/10 Background Runs

47.4 days, 6152 events, 130 events per day

F equivalent recoil energy (keV)

Freq

uenc

y

0 50 100 150 200

020

040

060

080

010

0012

00

AstroPle,  35,  (2012)  397.  

•  47.4  days  of  live  >me  recorded  •  A  background  of  130  events  

per  day  found  

Page 7: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Radon  Progeny  Recoils  

……

……

……

……

……

……

……

……

……

……

……

……

……

……

222Rn

α

218Po+  

……

……

……

……

……

……

……

……

……

……

……

……

……

…...

……

……

……

……

……

……

……

……

……

……

……

……

……

…..

218Po  

218Po  

α

20  µm  

Range  =  12  µm  

214Pb+  

- - - - - -

-

-

-

- 214Pb+  

0  V   0  V  -­‐32.5  kV  

AstroPle,  28,  (2007)  409.  

Page 8: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Texturized  thin  film  

•  Miraculously  the  guys  at  UNM  managed  to  create  a  texturized  0.9  micron  aluminized  mylar  thin  film  to  replace  the  wire  cathode.  

•  This  means  the  alphas  have  “no  place  to  hide.”  

•  This  has  been  deployed  on  DRIFT-­‐IId  in  Boulby.  

•  The  result  was  a  drop  from  130  events  per  day  down  to  a  few  events  per  day.  

NIMA,  794,  (2014)  33.  

Page 9: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

4.5 5.0 5.5 6.0

0.00

00.

001

0.00

20.

003

0.00

4

Time (ms)

Cur

rent

(arb

itrar

y un

its)

Discovery  of  Minority  Carriers  in  Mixtures  of  CS2  and  O2    

Rev.  Sci.  Inst.,  85,  (2014)  1.  

Page 10: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Examples  

2000 2500 3000 3500

050

100

150

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drift2d−20141218−01−0004−neut, event number 6950, line number = 1Peak Nips = 2633, Peak PI z = 49.65 cm

Sum X^2 = 0.31

this.sequence

input.recovered.3[this.sequence]

z  =  49.7  cm  

Page 11: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

2000 2500 3000 3500

050

100

150

drift2d−20141218−01−0005−neut, event number 3348, line number = 14Peak Nips = 2097, Peak PI z = 39.31 cm

Sum X^2 = 0.59

this.sequence

input.recovered.3[this.sequence]

Examples  

z = 39.3  cm  

Page 12: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

2000 2500 3000 3500

050

100

150

200

drift2d−20141218−01−0003−neut, event number 3560, line number = 6Peak Nips = 1731, Peak PI z = 30.28 cm

Sum X^2 = 0.93

this.sequence

input.recovered.3[this.sequence]

Examples  

z = 30.3  cm  

Page 13: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

2000 2500 3000 3500

0100

200

300

drift2d−20141218−01−0003−neut, event number 476, line number = 1Peak Nips = 3317, Peak PI z = 20.07 cm

Sum X^2 = 0.15

this.sequence

input.recovered.3[this.sequence]

Examples  

z = 20.1  cm  

Page 14: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Pellet  Shielding  

Page 15: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

2030

4050

Nips vs PI zBackground All Shielded, 433SumRisetime

54.7 days, 185 events, 3.38 +/− 0.2 events per day

Anode Nips

z (c

m)

Cathode

MWPC

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Cathode rate = 185 events, 3.38 +/− 0.25 events per day

Fiducial rate = 0 events, 0 +/− 0 events per day

Shielded  30-­‐10-­‐1  CS2-­‐CF4-­‐O2  Data  

•  54.7  days  of  data  analyzed  •  185  events  found  but  as  

expected  all  were  located  at  50  cm  away  from  the  detector,  i.e.  on  the  central  cathode.  

•  Define  a  background-­‐free  fiducial  region.  

•  In  order  to  interpret  this  as  a  limit  need  to  calibrate  the  detector…  

50   100   150   200  

F  equivalent  recoil  energy  (keV)  

Page 16: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

2030

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Nips vs PI zNeutrons All Shielded, 433SumRisetime

0.803 days, 14240 events, 17700 +/− 100 events per day

Anode Nips

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Cathode rate = 344 events, 429 +/− 23 events per day

Fiducial rate = 13896 events, 17300 +/− 150 events per day

Cf-­‐252  Neutron  Calibra>on  Data  

•  Exposed  the  detector  to  a  CF-­‐252  neutron  source  

•  As  expected  the  neutrons  distributed  themselves  more  or  less  uniformly  in  z  within  the  fiducial  region  

•  Since  neither  the  distribu>on  in  z  nor  NIPs  (ioniza>on)  is  truly  uniform  need  to  do  this  carefully…  

Page 17: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

2030

4050

Nips vs PI zDRIFT_run14_merged_900M

9.4 days, 829259 events, 88200 +/− 100 events per day

Anode Nips

z (c

m)

S

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GEANT  Cf-­‐252  Simula>on  Data  

•  Careful  GEANT  work  was  done  in  Sheffield  to  model  these  Cf-­‐252  exposures.  

•  Simula>on  is  more  than  10x  data.  

•  Only  a  sample  is  shown.  

Page 18: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

2030

4050

Nips vs PI zDRIFT_run14_merged_900M

9.4 days, 829259 events, 88200 +/− 100 events per day

Anode Nips

z (c

m)

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Cathode

MWPC

GEANT  Cf-­‐252  Simula>on  Data  

•  Drew  a  fine  grid  in  the  NIPs  vs  z  space.  

•  Counted  the  number  of  events  in  each  bin.  

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Page 19: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

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Nips vs PI zNeutrons All Shielded, 433SumRisetime

0.803 days, 14240 events, 17700 +/− 100 events per day

Anode Nips

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MWPC

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Cathode rate = 344 events, 429 +/− 23 events per day

Fiducial rate = 13896 events, 17300 +/− 150 events per day

Cf-­‐252  Neutron  Calibra>on  Data  

•  Did  the  same  for  the  experimental  data.  

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Page 20: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

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Cathode

MWPC

DRIFT-­‐IId  Detector  Efficiency  Map  

•  The  ra>o  of  Data/GEANT  gives  us  nuclear  recoil  efficiency  for  each  bin  in  this  space.  

•  Red  =>  0%,  White  =  100%  •  Take  it  out  for  a  test  run…  

Page 21: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

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010

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Nips vs PI zBackground All Unshielded, 433SumRisetime

45.4 days, 201 events, 4.43 +/− 0.3 events per day

Anode Nips

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Cathode rate = 187 events, 4.12 +/− 0.3 events per day

Fiducial rate = 14 events, 0.309 +/− 0.082 events per day

Unshielded  Data  

•  Detector  pellet  shielding  was  removed  before  and  a`er  the  shielded  runs.  

•  45.4  days  of  data  analyzed  •  14  events  found  in  the  fiducial  

region.  •  With  a  long  Co-­‐60  run  we  have  

ruled  out  rock-­‐gammas  as  a  source  of  these  events.  

•  These  are  rock-­‐neutrons  detected  at  a  rate  of                        0.31  +/-­‐  0.03  (sys)  +/-­‐  0.08  (stat)  events  per  day  

Page 22: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

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Nips vs PI zDRIFT_rock_run28_gypsum_unshielded_1100M

458 days, 697 events, 1.52 +/− 0.06 events per day

Anode Nips

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Cathode

MWPC

Unshielded  Simula>on  

•  Sheffield  simulated  neutrons  generated  in  the  walls  of  the  cavern  and  then  tracked  them  into  the  detector.  

•  The  GEANT  data  were  then  gridded  and  counted.  

•  This  data  was  then  mul>plied  by  the  efficiency  map  to  give  detected  events.  

•  GEANT  =  0.25  +/  -­‐  0.02  events  per  day  

•  Data  =  0.31  +/-­‐  0.03  (sys)  +/-­‐  0.08  (stat)  events  per  day  

•  Good  agreement!  

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Page 23: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

0 1000 2000 3000 4000 5000 6000

010

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Nips vs PI z100 GeV WIMPs on F

54.7 days, 700 events, 3.22 +/− 0.3 events per day

Anode Nips

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Cathode

MWPC

Cathode rate = 8 events, 0.173 +/− 0.061 events per day

Fiducial rate = 124 events, 2.68 +/− 0.24 events per day

Unshielded  Data  

•  Simulated  WIMP  events  are  created,  binned,  mul>plied  by  the  efficiency  map  to  give  detected  WIMP  rates.  

•  The  resul>ng  detected  rate  =>  cross-­‐sec>on  limits.  

0 1000 2000 3000 4000 5000 6000

010

2030

4050

Nips

z (c

m)

Page 24: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

SD  Limits  

1 10 100 1000 10000

Spin−Dependent WIMP−proton Limits

WIMP Mass (GeV)

WIM

P−pr

oton

SD

cro

ss s

ectio

n (p

b)

10−4

10−3

10−2

10−1

1

10

102

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106 NAIAD (2005)DMTPC (2010)COUPP (2012)PICASSO (2012)KIMS (2012)DRIFT−IId (2012)XENON100 (2013)SIMPLE (2014)DRIFT−IId+O2 (2015)NEWAGE (2015)PICO (2015)DRIFT−IId+O2 (2016)DRIFT−IId+O2 (150 days)DRIFT−IId+O2 (500 days)

Physics  of  the  Dark  Universe,  9-­‐10,  (2015)  1.  

AstroPle,  35,  (2012)  397.  

This  result  2016  

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SI  Limits  

1 10 100 1000 10000

Spin−Independent WIMP Limits

WIMP Mass (GeV)

WIM

P−nu

cleo

n cr

oss

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^2)

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10−36 DAMACDMS (2010)EDELWEISS (2011)SIMPLE (2012)COUPP (2012)ZEPLINIII (2012)XENON100 (2012)LUX (2013)DRIFT−IId+O2 (2016)DRIFT−IId+O2 (150 day)DRIFT−IId+O2 (500 day)

Page 26: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Head-­‐tail  analysis  

•  DRIFT  sensi>vity  to  HT  in  the  new  gas  mode  was  inves>gated.  

•  Method  of  extrac>ng  the  HT  parameter  from  data  has  been  discussed  for  DRIFT  in  Astropart.  Phy.,  31  (2009)  261.  

•  Analyzed  7  days  of  directed  source  neutron  data.  

•   Event  by  event  measurement  of  the  HT  parameter  was  done  using  η1  to  η2  ra>o.  

•   Can  now  study  HT  z,  thanks  to  fiducializa>on.  

 

Page 27: DM2016 DRIFT talk SnowdenIfft-Posted · 2016-03-08 · 0 1000 2000 3000 4000 5000 6000 0 10 20 30 40 50 Nips vs PI z Background All Shielded, 433SumRisetime 54.7 days, 185 events,

Head-­‐tail  results  

•  Improved  HT  sensi>vity  (as  expected)  due  to  longer  recoil  tracks  from  C  and  F-­‐recoil  components  in  this  data  set  compared  to  shorter  S-­‐recoils  in  the  old  data.    

•  HT  sensi>vity  at  lower  energy  is  due  to  lower  hardware  and  analysis  thresholds.  

•  HT  paper  in  prepara>on.  

•  Blue  circle  points:  New  results  including  C  and  F-­‐recoil  components.  

•  Black  triangle  points:  Results  obtained  with  shorter  S-­‐recoils  see  Astropart.  Phy.,  31  (2009)  261.  

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DRIFT  Progress  

•  In  2007  we  published  results  from  DRIFT-­‐IIa  showing  500  accepted  RPR  events  per  day.  

•  In  2012  this  had  been  reduced  to  130  events  per  day.    •  In  2014  with  the  thin  film  cathode  this  had  been  reduced  to  3  events  per  

day.    •  And  in  2016  with  O2  this  had  been  reduced  to  0  events  in  54.7  days.  

•  In  limit  seung  terms  this  is  an  improvement  of  x12,000  in  9  years,  x2.8  per  year  bea>ng  Moore’s  Law  as  dark  maHer  physicists  do.  

•  DRIFT  is  background  free.  

•  New  direc>onal  results  are  coming.