Novel Techniques for Detecting sub-GeV Dark Matter
Transcript of Novel Techniques for Detecting sub-GeV Dark Matter
![Page 1: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/1.jpg)
Novel Techniques for Detecting sub-GeV
Dark MatterTien-Tien Yu
YITP - Stony Brookwith Rouven Essig, Marivi Fernandez Serra, Jeremy Mardon,
Adrián Soto, Tomer Volansky 1504.XXXXX
April 29, 2015 UC Irvine Theory Seminar
![Page 2: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/2.jpg)
candidates for DM
![Page 3: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/3.jpg)
candidates for DM
WIMPs theoretically motivated
WIMP miracle gives detectable signatures
![Page 4: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/4.jpg)
current state of affairs
1310.8327
![Page 5: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/5.jpg)
current state of affairs
1310.8327??
ER =q2
2mN⇠
m2�v
2
mN
![Page 6: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/6.jpg)
nucleus
DM
*not to scale
e-
![Page 7: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/7.jpg)
DM
ER =q2
2mN⇠
m2�v
2
mN
*not to scale
e-
nucleus
![Page 8: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/8.jpg)
DMsignal: heat
phonons scintillation photons ionization electrons
ER =q2
2mN⇠
m2�v
2
mN
*not to scale
e-
nucleus
![Page 9: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/9.jpg)
DM
ER =q2
2mN⇠
m2�v
2
mN
m� = 100 GeV, ER ⇠ 1 MeV
*not to scale
e-
nucleus
![Page 10: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/10.jpg)
DM
m� = 100 MeV, ER ⇠ 1 eV
ER =q2
2mN⇠
m2�v
2
mN
*not to scale
e-
nucleus
![Page 11: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/11.jpg)
candidates for DM
![Page 12: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/12.jpg)
sub-GeV DM is theoretically motivated
Hidden Photon Mediator
MDM/EDM
DM DM
SM SM
dipole moment
Hall et al [0911.1120] Essig et al [1108.5383] Lin et al [1111.0293] Chu et al [1112.0493]
Sigurdson et al, Phys. Rev. D70 (2004) 083501 + Erratum-ibid.
Banks et al [1007.5515] Graham et al [1203.2531]
Kadota and Silk [1402.7295]
DM DM
SM SM
A’
Akinetic mixing
Strongly Interacting
Boddy et al [1408.6532] Hochberg et al [1402.5143,1411.3727]
![Page 13: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/13.jpg)
DM
nucleus
*not to scale
�Ee = ~q · ~v � q2
2µ�N
⇠ 1
2eV ⇥
⇣ m�
MeV
⌘
e-
![Page 14: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/14.jpg)
DM
e-
*not to scale
signal: a few ionized
electrons
m� = 100 MeV, ER ⇠ 50 eV
�Ee = ~q · ~v � q2
2µ�N
⇠ 1
2eV ⇥
⇣ m�
MeV
⌘
nucleus
![Page 15: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/15.jpg)
DM
e-
*not to scale
signal: a few ionized
electrons
m� = 100 MeV, ER ⇠ 50 eV
�Ee = ~q · ~v � q2
2µ�N
⇠ 1
2eV ⇥
⇣ m�
MeV
⌘
nucleus
*sensitive to precise form of electron energy levels and wave functions in
target
![Page 16: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/16.jpg)
electron scatteringXENON10 limits
R. Essig, A. Manalaysay, J. Mardon, P. Sorenson, T. Volansky 1206.2644
![Page 17: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/17.jpg)
electron energy
• noble gases: ~10 eV
• semiconductors: ~1 eV
![Page 18: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/18.jpg)
Calculation Ingredients
![Page 19: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/19.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
�e =µ2�e
16⇡m2�m
2e
|M�e(q)|2
q2=↵2m2e
�(q) = �e ⇥ |FDM (q)|2
particle physics
![Page 20: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/20.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
⌘(vmin) =
Z
vmin
d3v
vfMB(~v)
astrophysics
vmin =ER + EB
q+
q
2m�
![Page 21: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/21.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
���fi!i
0(~q,~k)���2=
V
(2⇡)3
Z
BZd3k0
����Z
d3x ⇤i
0,
~
k
0(~x) i,
~
k
(~x)ei~q·~x����2
solid state physics
probability of going from state i to i’
![Page 22: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/22.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
number of target nuclei per unit mass
local DM density
R = NT⇢�m�
Z
ER,cut
d lnERdh�vid lnER
energy threshold
![Page 23: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/23.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
���fi!i
0(~q,~k)���2=
V
(2⇡)3
Z
BZd3k0
����Z
d3x ⇤i
0,
~
k
0(~x) i,
~
k
(~x)ei~q·~x����2
computationally difficult!
solid state physics
analytic numerical
![Page 24: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/24.jpg)
valence bands
conduction bands
band gap
e-
1
detector2
light heat electric charge
e-e-
e-
1
light heat electric charge
electrons in a solid are part of a complicated, many-body system
gas solid
![Page 25: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/25.jpg)
analytic approximations• semi-classical
approach
• initial wave functions are spherical
• plane wave final states with altered mass
• no interference
• good for high q
1203.2531
![Page 26: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/26.jpg)
Single-electron detection
1108.5383
![Page 27: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/27.jpg)
Single-electron detection
1108.5383
*assumed single-electron detection
![Page 28: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/28.jpg)
Recoil energy spectrum
� � �� �� �� �� �� ���
��
������������������� � � � � � � � �� �� ��
�� [��]
���
[������/��
/����]
������ �� ���������
��� (�) = �--- ��� (�) = ���/�----- ��� (�) = (���/�)�
��
�� = � ����� = �� ���
![Page 29: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/29.jpg)
valence bands
conduction bands
band gap
e-
e-
1
detector2
light heat electric charge
What happens in step 2?
![Page 30: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/30.jpg)
Energy to create an electron-hole pair
previously, we thought of the experimental parameter as recoil energy thresholds.
!Instead, experimentalists measure
actual number of electrons.
Can use the following conversion: Ge: 2.9 eV/electron Si: 3.6 eV/electron
![Page 31: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/31.jpg)
Recoil energy spectrum
� � �� �� �� �� �� ���
��
������������������� � � � � � � � �� �� ��
�� [��]
���
[������/��
/����]
������ �� ���������
��� (�) = �--- ��� (�) = ���/�----- ��� (�) = (���/�)�
��
�� = � ����� = �� ���
![Page 32: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/32.jpg)
interlude
![Page 33: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/33.jpg)
semiconductors
valence
conduction
band gap ~0.67 eV for Ge ~1.11 eV for Si
![Page 34: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/34.jpg)
Band structure
k-points
valence!bands
conduction!bands
![Page 35: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/35.jpg)
semiconductors
• electron wave functions inside a crystal are complicated, but there are methods to approximate them
• we assume a wavefunction of the form:
i,
~
k
(~x) =1pV
X
G
i
(~k + ~
G)ei(~
k+~
G)~x
lives in Brillouin Zone
reciprocal lattice vector
![Page 36: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/36.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
���fi!i
0(~q,~k)���2=
V
(2⇡)3
Z
BZd3k0
����Z
d3x ⇤i
0,
~
k
0(~x) i,
~
k
(~x)ei~q·~x����2
probability of exciting an electron from valence band i to conduction band i’
solid state physics
![Page 37: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/37.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
���fi!i
0(~q,~k)���2=
V
(2⇡)3
Z
BZd3k0
����Z
d3x ⇤i
0,
~
k
0(~x) i,
~
k
(~x)ei~q·~x����2
probability of exciting an electron from valence band i to conduction band i’
solid state physics
valence
conduction
band gap
![Page 38: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/38.jpg)
ingredients
dh�vid lnER
=�e
8µ2�e
Zq dq|f(k, q)|2|FDM (q)|2⌘(vmin)
���fi!i0(~q,~k)���2=
�����X
G
⇤i0(~k + ~G+ ~q) i(~k + ~G)
�����
2
���fi!i
0(~q,~k)���2=
V
(2⇡)3
Z
BZd3k0
����Z
d3x ⇤i
0,
~
k
0(~x) i,
~
k
(~x)ei~q·~x����2
mild directional dependence we ignore for now
solid state physics
![Page 39: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/39.jpg)
• open source code that calculates electronic structure within density functional theory (DFT) using plane waves and pseudopotentials
• use a mesh of 64 k-vectors, 100 bands, and a regular grid of G-vectors ���~k + ~G
���2
2me< Ec
http://www.quantum-espresso.org/
cut-off energy ~70 Ry
![Page 40: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/40.jpg)
� �� �� �� �� �� �������
�����
�����
�����
����
�����
�����
�����
[�� ]
� ���[�]
��=� � ��=�� � ��=��� �
������
����� ������
�����
�����
choosing parameters
� � �� �� �� �� �� ������
����
����
����
����
����
����
����
����� � � � � � � � ��
�� [� ]
(��/��
�(�������))/(��/��
�(����))
������ �� ���������
��=� ���
���� ����
����
���� ����
vmin > vesc + vE
![Page 41: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/41.jpg)
end of interlude
![Page 42: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/42.jpg)
Cross-section reach vs. detector threshold
1 10 100 100010-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-33
m� [MeV]
�e[cm2]
FDM(q)=1
1e
5e
10e
15e--- GeSi XENON10
1 10 100 100010-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-33
m� [MeV]�e[cm2]
FDM(q)=(�me /q)2
1e
5e
10e 15e
--- GeSi
XENON10
Freeze-In
smaller atomic mass = more electrons per target mass
Si wins at high masses and low thresholds
1 kg-year, zero background *preliminary
![Page 43: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/43.jpg)
Cross-section reach vs. detector threshold
smaller bandgap = higher rate
Ge wins at low masses and high thresholds
1 10 100 100010-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-33
m� [MeV]
�e[cm2]
FDM(q)=1
1e
5e
10e
15e--- GeSi XENON10
1 10 100 100010-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-33
m� [MeV]�e[cm2]
FDM(q)=(�me /q)2
1e
5e
10e 15e
--- GeSi
XENON10
Freeze-In
1 kg-year, zero background *preliminary
![Page 44: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/44.jpg)
� �� ��� ���� �����-����-����-����-����-����-����-����-���-���-����-��
�� [���]
��[��� ]
���(�)=�
��
��
--- ����
�������
����
����
������-���
� �� ��� ���� �����-����-����-����-����-����-����-����-���-���-����-��
�� [���]
��[��� ]
���(�)=�
��
��
--- ����
�������
�
��� �
���
�������
����/���
��
Heavy A’
MDM
![Page 45: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/45.jpg)
Light A’
EDM
� �� ��� ���� �����-����-����-����-����-����-����-����-���-���-����-����-����-����-����-����-��
�� [���]
��[��� ]
���(�)=���/�
��
��
--- ���� �����
�
��
����
������
�����
� �� ��� ���� �����-����-����-����-����-����-����-����-���-���-����-����-��
�� [���]
��[��� ]
���(�)=(���/�)�
��
��
���
--- ����
�����
������-��
���
������
����
�����
![Page 46: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/46.jpg)
1 10 100 100010-4510-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-3310-3210-3110-3010-29
m� [MeV]
�e[cm2]
FDM(q)=1
XENON10
SuperCDMS
DAMIC
Experimental projections
• DAMIC: 1. 1 kg-day, 4e, 0.008=3.6 events 2. 1 kg-day, 3e, 0.025=3.6 events 3. 50 kg-days, 4e, 0.4=3.8 events 4. 50 kg-days, 3e, 1.2=4.3 events • SuperCDMS 1. 20 kg-years, Ge, 4e, 3.6 events (eff=0.7) 2. 20 kg-years, Ge, 1e, 3.6 events (eff=0.7) 3. 10 kg-years, Si, 4e, 3.6 events (eff=0.7) 4. 10 kg-years, Si, 1e, 3.6 events (eff=0.7)
current DAMIC limit: 107 g-days, 11e
1 10 100 100010-4510-4410-4310-4210-4110-4010-3910-3810-3710-3610-3510-3410-3310-3210-3110-3010-2910-28
m� [MeV]
�e[cm2]
FDM(q)=(�me /q)2
XENON10
SuperCDMS
DAMIC
*preliminary
![Page 47: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/47.jpg)
annual modulation
Sun
Earth June
Earth Dec
DM halo
DM “wind”
![Page 48: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/48.jpg)
annual modulation
� �� ��� �������
���
���
���
���
�� [��]
� ���
��� (�) = �--- ��� (�) = (���/�)�
��
��
� � �� �� �� �� ����
����
���
����
���
����
��
����
���
����
���
����
�� [��]
� ���
��� (�) = �--- ��� (�) = (���/�)�
��=�� ���
��=� ���
��
fmod
=R
max
�Rmin
2Rmean
sits on tail of velocity distribution
could also consider gravitational focusing, c.f. 1308.1953
*preliminary
![Page 49: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/49.jpg)
annual modulation
� �� ��� ������-����-����-����-����-����-����-����-����-���-���-����-����-����-����-����-����-��
�� [���]
��[��� ]
���(�)=�
�������
����� ��
��������
�����
� �� ��� ������-����-����-����-����-����-����-����-����-���-���-����-����-����-����-����-����-����-��
�� [���]
��[��� ]
���(�)=(���/�)�
�������
����� ��
��������
�����
*preliminary
![Page 50: Novel Techniques for Detecting sub-GeV Dark Matter](https://reader030.fdocuments.us/reader030/viewer/2022012616/619e582109ac0b43b47db9b4/html5/thumbnails/50.jpg)
conclusions• sub-GeV dark matter is theoretically motivated
• but this mass range is currently unexplored by direct detection experiments, which rely on nuclear recoil.
• exchanging nuclear recoil for electron recoil is a possible resolution
• The best projections so far are theory predictions for noble gases
• semiconductor experiments have the potential to have a further reach due to the small band gap
• ongoing discussions with CDMS and DAMIC