K J Kang’s research while affiliated with Tsinghua University and other places

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Publications (80)


Projected WIMP sensitivity of the CDEX-50 dark matter experiment
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July 2024

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16 Reads

Journal of Cosmology and Astroparticle Physics

X.P. Geng

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CDEX-50 is a next-generation project of the China Dark Matter Experiment (CDEX) that aims to search for dark matter using a 50-kg germanium detector array. This paper comprises a thorough summary of the CDEX-50 dark matter experiment, including an investigation of potential background sources and the development of a background model. Based on the baseline model, the projected sensitivity of weakly interacting massive particle (WIMP) is also presented. The expected background level within the energy region of interest, set to 2–2.5 keVee, is ∼0.01 counts keVee −1 kg −1 day −1 . At 90% confidence level, the expected sensitivity to spin-independent WIMP-nucleon couplings is estimated to reach a cross-section of 5.1 × 10 −45 cm 2 for a WIMP mass of 5 GeV/c 2 with an exposure objective of 150 kg·year and an analysis threshold of 160 eVee. This science goal will correspond to the most sensitive results for WIMPs with a mass of 2.2–8 GeV/c 2.

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Projected WIMP sensitivity of the CDEX-50 dark matter experiment

July 2024

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41 Reads

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6 Citations

CDEX-50 is a next-generation project of the China Dark Matter Experiment (CDEX) that aims to search for dark matter using a 50-kg germanium detector array. This paper comprises a thorough summary of the CDEX-50 dark matter experiment, including an investigation of potential background sources and the development of a background model. Based on the baseline model, the projected sensitivity of weakly interacting massive particle (WIMP) is also presented. The expected background level within the energy region of interest, set to 2–2.5 keVee, is ∼0.01 counts keVee⁻¹ kg⁻¹ day⁻¹. At 90% confidence level, the expected sensitivity to spin-independent WIMP-nucleon couplings is estimated to reach a cross-section of 5.1 × 10⁻⁴⁵ cm² for a WIMP mass of 5 GeV/c² with an exposure objective of 150 kg·year and an analysis threshold of 160 eVee. This science goal will correspond to the most sensitive results for WIMPs with a mass of 2.2–8 GeV/c².


Search for solar axions by Primakoff effect with the full dataset of the CDEX-1B Experiment

May 2024

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39 Reads

We present the first limit on gAγ coupling constant using the Bragg-Primakoff conversion based on an exposure of 1107.5 kg days of data from the CDEX-1B experiment at the China Jinping Underground Laboratory. The data are consistent with the null signal hypothesis, and no excess signals are observed. Limits of the coupling gAγ < 2.08 × 10 −9 GeV −1 (95% C.L.) are derived for axions with mass up to 100 eV/c 2. Within the hadronic model of KSVZ, our results exclude axion mass > 5.3 eV/c 2 at 95% C.L.


Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated-Dark-Matter-Electron Analysis in Semiconductors

April 2024

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42 Reads

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1 Citation

Physical Review Letters

Recently a dark matter-electron (DM-electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM-electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM-electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM-electron interaction is presented with the 205.4 kg · day dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of 5-15 keV=c 2 , achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than 0.1 MeV=c 2 is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM-electron analyses with semiconductor detectors.


FIG. 1. Velocity components of isotropic DM velocity distribution. v DM is DM particle's velocity. v E is the Earth's velocity relative to the DM model, and for SHM it's Earth's velocity with respect to the Galactic rest frame. v lab is the velocity seen by the lab. v max is the maximum velocity of the model. v DM ¼ v lab þ v E .
FIG. 2. Reconstructed spectrum of the c → f process for 10 GeV=c 2 DM from SHM in the heavy mediator scenario. The shaded area corresponds to the original result calculated by the EXCEED-DM package [56]. The blue and red lines are reconstructed results using the inverse square and uniform distribution. Solid lines from darker to dimmer represent the contributions of 11 velocity bins with bin width of 50 km=s from 0-550 km=s calculated by the modified EXCEED-DM package. The analysis threshold of CDEX-10 is represented by a black dashed line.
FIG. 3. (a) SRDM flux distributions with different m χ and ¯ σ e . SRDM flux in the light mediator scenario from Ref. [34] is depicted in dashed lines. Other lines correspond to the heavy mediator scenario, and results from Refs. [34] and [35] are consistent. The strips represent the binning of the velocity distributions. (b) Reconstructed HPGe detector response in the heavy mediator scenario to SRDM based on the distributions calculated by DaMaSCUS-SUN [60]. The detector's resolution is determined by 35.8 þ 16.6 × ffiffiffi ffi E p ðeVeeÞ [15], where E is in
Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated-Dark-Matter–Electron Analysis in Semiconductors

April 2024

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54 Reads

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6 Citations

Physical Review Letters

Recently a dark matter–electron (DM–electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM–electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM–electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM–electron interaction is presented with the 205.4 kg · day dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of 5 – 15 keV / c 2 , achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than 0.1 MeV / c 2 is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM–electron analyses with semiconductor detectors. Published by the American Physical Society 2024


First Search for Light Fermionic Dark Matter Absorption on Electrons Using Germanium Detector in CDEX-10 Experiment

April 2024

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42 Reads

We present the first results of the search for sub-MeV fermionic dark matter absorbed by electron targets of Germanium using the 205.4 kg·day data collected by the CDEX-10 experiment, with the analysis threshold of 160 eVee. No significant dark matter (DM) signals over the background are observed. Results are presented as limits on the cross section of DM-electron interaction. We present new constraints of cross section in the DM range of 0.1-10 keV/c2 for vector and axial-vector interaction. The upper limit on the cross section is set to be 5.5×10^{-46} cm2 for vector interaction, and 1.8×10^{-46} cm 2 for axial-vector interaction at DM mass of 5 keV/c2.


Constraints on the Blazar-Boosted Dark Matter from the CDEX-10 Experiment

April 2024

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26 Reads

We report new constraints on light dark matter (DM) boosted by blazars using the 205.4 kg day data from the CDEX-10 experiment located at the China Jinping Underground Laboratory. Two representative blazars, TXS 0506+56 and BL Lacertae are studied. The results derived from TXS 0506+56 exclude DM-nucleon elastic scattering cross sections from 4.6 × 10^{-33} cm^{2} to 1 × 10^{-26} cm^{2} for DM masses between 10 keV and 1 GeV, and the results derived from BL Lacertae exclude DM-nucleon elastic scattering cross sections from 2.4 × 10^{-34} cm^{2} to 1 × 10{-26} cm^{2} for the same range of DM masses. The constraints correspond to the best sensitivities among solid-state detector experiments in the sub-MeV mass range. SuperCDMS [8], CoGeNT [9] and CDEX [10-20] are dedicated to probing DM-nucleus (χ-N) elastic scattering through spin-independent (SI) and spin-dependent interactions, yet no clear signals have been observed to date.


Probing Dark Matter Particles from Evaporating Primordial Black Holes via Electron Scattering in the CDEX-10 Experiment

April 2024

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34 Reads

Dark matter (DM) is a major constituent of the Universe. However, no definite evidence of DM particles (denoted as “χ”) has been found in DM direct detection (DD) experiments to date. There is a novel concept of detecting χ from evaporating primordial black holes (PBHs). We search for χ emitted from PBHs by investigating their interaction with target electrons. The examined PBH masses range from 1×10 15 to 7×10 16 g under the current limits of PBH abundance f P BH. Using 205.4 kg·day data obtained from the CDEX-10 experiment conducted in the China Jinping Underground Laboratory, we exclude the χ–electron (χ–e) elastic-scattering cross section σ χe ∼ 5 × 10 −29 cm 2 for χ with a mass m χ ≲ 0.1 keV from our results. If (m χ , σ χe ) can be determined in the future, DD experiments are expected to impose strong constraints on f P BH for large M P BH s.


FIG. 1. Velocity components of isotropic DM velocity distribuion. vDM is DM particle's velocity. vE is the Earth's velocity relative to the DM model, and for SHM it's Earth's velocity with respect to the Galactic rest frame. v lab is the velocity seen by the lab. vmax is the maximum velocity of the model, and the Galactic escape velocity for SHM.
FIG. 2. Reconstructed SHM result of the c→f process for 10 GeV DM in the heavy mediator scenario. The shaded area corrsponds to the original result calculated by the EXCEED-DM package. The red and blue lines are reconstructed results using the inverse-square distribuion and the uniform distribution. Solid lines from darker to dimmer represent the contributions of 11 velocity bins with bin width of 50 km/s from 0−550 km/s. The energy threshold of C10B-Ge1 is represented by black dash line.
FIG. 3. (a) SRDM flux distributions with different mχ and σe. SRDM flux in the light mediator scenario from Ref. [29] is dipicted in dash lines. Other lines correspond to the heavy mediator scenario, and results from Ref. [29] and DaMaSCUS-SUN presented by Ref. [30] are consistent. The strips in the figure represent the binning of the velocity distributions. (b) Reconstructed HPGe detector response in the heavy mediator scenario to SRDM based on the distributions calculated by DaMaSCUS-SUN and contributions from different velocity bins calculated by EXCEED-DM. Spectra of v→f, c→f and c→cd process are cut off at 10 keV, 10 keV and 2 keV. The spectrum reconstructed with SRDM flux from Ref. [29] is similar. The detector's resolution is determined by 35.8+16.6× √ E (eV) [31]. Experimental data with known radioactive peaks removed of C10B-Ge1 [31] is also dipicted in (b).
Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated Dark Matter-Electron Analysis in Semiconductors

September 2023

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119 Reads

Recently a Dark Matter-electron (DM-e) paradigm has drawn much attention. Models beyond the Standard Halo Model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this letter, a Velocity Component Analysis method dedicated to swift analysis of Accelerated DM-electron interactions via semiconductor detectors is proposed and the first HPGe detector-based Accelerated DM-electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV Solar Reflected DM-electron interaction is presented with the 205.4 kg·day dataset from the CDEX-10 experiment. In the heavy mediator scenario, the result excels in the mass range from 5−15 keV/c 2 , achieving a three orders of magnitude improvement comparing with previous semiconductor experiments, and is comparable to currently the best direct detection experiments. In the light mediator scenario, the strongest constraint for DM lighter than 0.1 MeV/c 2 is presented. The result proves the feasibility and demonstrates the vast potential of the Velocity Component Analysis technique in future Accelerated DM-electron analysis with semiconductor detectors.



Citations (39)


... The CDEX facility is currently developing its third phase, the so-called CDEX-50 [108], as a next generation project. In this phase of the experiment, it is planned to have a detector array consisting of 50 kg of high-purity germanium. ...

Reference:

Probing active-sterile neutrino transition magnetic moment on coherent elastic solar neutrino-nucleus scattering
Projected WIMP sensitivity of the CDEX-50 dark matter experiment

... Although the extremely weak interactions of FIMPs suggest that testing the freeze-in mechanism might be highly challenging, recent developments have shown this to be increasingly feasible. For example, an increase in DM direct detection rates occurs in the case of GeV DM with a light mediator [12], in cases with sub-GeV DM particles [13][14][15], or due to the boost induced by the scattering of DM particles off electrons in the Sun [16][17][18]. In addition, the feeble coupling between the DM and the mediator can result in a sizable decay length for the mediator, producing distinctive signatures in colliders that can be observed, such as displaced vertices or long-lived particles [19][20][21][22][23][24]. ...

Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated-Dark-Matter–Electron Analysis in Semiconductors

Physical Review Letters

... The χ can also be characterized as Hawking radiation [75][76][77][78][79][80][81][82][83][84]. An evaporating PBH is a novel source of χ [85][86][87][88] or other new particles [89][90][91] beyond the standard model (SM). For convenience, the scenario of "a PBH evaporating χ" is abbreviated as "PBHeDM". ...

Search for boosted keV-MeV light dark matter particles from evaporating primordial black holes at the CDEX-10 experiment

Physical Review D

... In DD experiments solar neutrinos can induce CEνNS events, as well as elastic neutrino-electron scattering. In this context, we consider the latest data of the CDEX-10 experiment [72] which has a primary goal of searching light DM candidates [73]. The CDEX-10 collaboration has reported neutrino-nucleus event rates from solar neutrinos with 205.4 kg day exposure using a p-type point contact germanium (PPCGe) detector array. ...

Search for exotic interactions of solar neutrinos in the CDEX-10 experiment

Physical Review D

... Page 4 of 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 123456-5 [22] . 5 of 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 123456-6 represents the analysis threshold [26] . and PandaX-4T(black line), are superimposed [26] . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 123456-8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Weakly Interacting Massive Particles (WIMPs) are among the most well-known candidates for dark matter. ...

Exotic Dark Matter Search with the CDEX-10 Experiment at China's Jinping Underground Laboratory

Physical Review Letters

... The idea is that the DM (χ) is absorbed by nuclear or atomic target (T) while emitting an undetectable neutrino (ν), χ þ T → ν þ T 0 , while the target (T 0 ) recoils. Such signals have been searched at PandaX-4T [23,24], Majorana [25], EXO-200 [26], and CDEX [27,28]. ...

Exotic Dark Matter Search with the CDEX-10 Experiment at China’s Jinping Underground Laboratory

Physical Review Letters

... On the other hand, when dark matter is accelerated by supernova neutrinos, namely SNνBDM, the dark matter velocity will be on the order of 10 −2 c because of the dynamics of SNνBDM. This may lead to the plasmon excitation in the semiconductor system [77,78], including SENSEI [79], DAMIC [80], CDEX [81],EDELWEISS [82], and SuperCDMS [83]. ...

Constraints on Sub-GeV Dark Matter-Electron Scattering from the CDEX-10 Experiment

Physical Review Letters

... The most relevant constraints in such cases are derived from experiments such as PandaX-xT [42], XENONnT [43], LUX-ZEPLIN [44], and XLZD [45] amongst others. Heavy DM search is also underway with XENONnT [46] and sub-GeV DM searches with SuperCDMS [47][48][49], EDELWEISS [50], CRESST-III [51], DarkSide-50 [52], CDEX-10 [53], DAMIC-M [54], SENSEI [55], etc. ...

Constraints on Sub-GeV Dark Matter–Electron Scattering from the CDEX-10 Experiment

Physical Review Letters

... With COSINE-100 data, we searched for the inelastic scattering of BDM (IBDM) [18] induced by the existence of another dark sector particle [29,30]. Recently, searches for cosmic-ray BDM interacting with protons in dark matter detectors with energies of a few keV [36,37], as well as in neutrino detectors with energies between a few MeV [38] and a few GeV [39], were performed. ...

Constraints on sub-GeV dark matter boosted by cosmic rays from the CDEX-10 experiment at the China Jinping Underground Laboratory

Physical Review D

... While the bulk of CRs with energy much below the EeV are believed to originate within the Milky Way (MW) [39,40] and to be mostly protons below the PeV [41], UHECRs above the EeV scale are today understood as having an extragalactic origin, see e.g., [42][43][44], and a mixed composition with heavier nuclei dominating over protons, see, e.g., [15,16,[45][46][47][48][49][50]. We therefore employ the CR spectrum dΦ CR =dE CR from [15] and, by considering up-scatterings in the MW with the line-of-sight integral D eff ≈ 10 kpc as in [14] (see, e.g., [51][52][53] for studies of the uncertainties on D eff , where the RνB case is analogous to relativistic DM fluxes and cored profiles like Isothermal), we obtain the flux reported as a dotdashed line in Fig. 1 (see further). Our calculation improves over the analogous one [14] by going beyond the proton-only composition of CRs and by implementing the momentum transfer dependence and DIS in the cross section. ...

Constraints on sub-GeV dark matter boosted by cosmic rays from the CDEX-10 experiment at the China Jinping Underground Laboratory

Physical Review D